ANL-MGR-GS-000001 REV 01 September 2003 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 3 September 2003 
CONTENTS 
Page 
1. PURPOSE.............................................................................................................................. 11 
2. QUALITY ASSURANCE...................................................................................................... 13 
3. USE OF SOFTWARE ............................................................................................................ 13 
3.1 SOFTWARE TRACKED BY CONFIGURATION MANAGEMENT........................ 13 
3.1.1 Software Routines ................................................................................................ 14 
3.1.2 Software Used in the Current Revision of this Scientific Analysis ..................... 17 
3.2 EXEMPT SOFTWARE ................................................................................................. 20 
4. INPUTS.................................................................................................................................. 21 
4.1 DATA AND PARAMETERS ....................................................................................... 21 
4.2 CRITERIA..................................................................................................................... 21 
4.3 CODES AND STANDARDS ........................................................................................ 22 
5. ASSUMPTIONS.................................................................................................................... 22 
5.1 USE OF QUATERNARY VOLCANOES .................................................................... 22 
5.2 ALL VOLCANIC EVENTS PRODUCE AT LEAST ONE ERUPTIVE CENTER.... 23 
5.3 LOCATION OF ERUPTIVE CENTERS ALONG THE LENGTH OF A DIKE OR 
DIKE SEGMENT.......................................................................................................... 23 
6. SCIENTIFIC ANALYSIS ...................................................................................................... 24 
6.1 INTRODUCTION ......................................................................................................... 24 
6.1.1 Features, Events, and Processes ........................................................................... 25 
6.2 VOLCANIC HISTORY OF THE YUCCA MOUNTAIN REGION............................ 27 
6.3 THE PROBABILISTIC VOLCANIC HAZARD ANALYSIS ..................................... 30 
6.3.1 The Probabilistic Volcanic Hazard Analysis Process .......................................... 30 
6.3.2 Definitions and Parameters of a Volcanic Event and Implications for 
Alternative Probability Calculations .................................................................... 37 
6.3.3 Conceptual Models of Volcanism and Formulation of Probability Models ........ 43 
6.4 THE CRATER FLAT STRUCTURAL DOMAIN ....................................................... 48 
6.4.1 Internal Structure and Boundaries of the Crater Flat Basin ................................. 50 
6.4.2 Probabilistic Volcanic Hazard Analysis Volcanic Source Zones: 
Relationship to Crater Flat Structural Features and the Probability of Dike 
Intersection........................................................................................................... 55 
6.5 RECALCULATION OF FREQUENCY OF INTERSECTION AND 
DEVELOPMENT OF DISTRIBUTIONS FOR LENGTH AND ORIENTATION 
OF DIKES AND FOR THE NUMBER OF ERUPTIVE CENTERS WITHIN THE 
PROPOSED REPOSITORY FOOTPRINT.................................................................. 58 
6.5.1 Formulation.......................................................................................................... 61 
6.5.2 Implementation..................................................................................................... 76 
6.5.3 Results .................................................................................................................. 94 
6.5.4 Impact of 1999 Aeromagnetic Data on Frequency of Intersection.................... 105 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 4 September 2003 
CONTENTS (Continued) 
Page 
7. CONCLUSIONS................................................................................................................... 113 
7.1 SUMMARY OF SCIENTIFIC ANALYSIS ............................................................... 113 
7.2 OUTPUTS BASED ON THE PROPOSED LICENSE APPLICATION 
FOOTPRINT (BLOCKS 1, 2, 3, AND 5) ................................................................... 114 
7.3 UNCERTAINTIES ...................................................................................................... 115 
8. INPUTS AND REFERENCES ............................................................................................. 115 
8.1 DOCUMENTS CITED................................................................................................ 115 
8.2 CODES, STANDARDS, REGULATIONS, AND PROCEDURES ........................... 122 
8.3 DATA, LISTED BY DATA TRACKING NUMBER ................................................ 122 
8.4 SOFTWARE................................................................................................................ 123 
8.5 OUTPUT DATA.......................................................................................................... 124 
ATTACHMENT I ADDRESSING YUCCA MOUNTAIN REVIEW PLAN FINAL 
REPORT ACCEPTANCE CRITERIA RELATED TO THE 
DEFINITION OF EVENTS WITH PROBABILITIES GREATER 
THAN 10-8 PER YEAR AND VOLCANIC DISRUPTION OF 
WASTE PACKAGES ................................................................................I-1 
ATTACHMENT II DEVELOPMENT OF FOOTPRINT POLYGON FOR THE 
PROPOSED REPOSITORY........................................................................II 
ATTACHMENT III DEVELOPMENT OF DISTRIBUTIONS FOR NUMBER OF 
ERUPTIVE CENTERS PER VOLCANIC EVENT AND AVERAGE 
SPACING BETWEEN E........................................................................ III-1 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 5 September 2003 
FIGURES 
Page 
1. Flowchart for Computation of Frequency of Intersection of Proposed Repository by 
a Dike ...................................................................................................................................15 
2. Flowchart for Computatio n of Conditional Distributions for Length and Azimuth of 
Intersecting Dike and Number of Eruptive Centers Within the Proposed Repository 
Given Intersection of This Footprint by a Dike ....................................................................18 
3. Location and Age of Post-Miocene (< 5.3 million years (m.y).) Volcanoes (or 
Clusters Where Multiple Volcanoes Have Indistinguishable Ages) in the Yucca 
Mountain Repository ............................................................................................................27 
4. Composite Distribution for Dike Length Averaged Across All 10 Probabilistic 
Volcanic Hazard Analysis Experts .......................................................................................39 
5. Conceptual Diagram Comparing Event Definitions from the Probabilistic Volcanic 
Hazard Analysis and Reamer: Implications for Eruption and Intrusion Probabilities 
Based on Different Event Definitions ...................................................................................40 
6. Composite Distribution for the Distance from the Point Volcanic Event to the End of 
the Dike Averaged Across All 10 PVHA Experts ................................................................44 
7. Local Structural Domains and Domain Boundaries of the Yucca Mountain 
Repository and Internal Structures of the Crater Flat Basin and Selected Parts of 
Adjacent Domains.................................................................................................................49 
8. Schematic Cross Section of the Crater Flat Basin, from Seismic, Reflection Surficial 
Geology, and Borehole Information .....................................................................................51 
9a. Local Structural Domains and Domain Boundaries of the Yucca Mountain 
Repository and Internal Structures of the Crater Flat Basin and Selected Parts of 
Adjacent Domains.................................................................................................................56 
9b. Local Structural Domains and Domain Boundaries of the Yucca Mountain 
Repository and Internal Structures of the Crater Flat Basin and Selected Parts of 
Adjacent Domains.................................................................................................................57 
10. Schematic Illustrating Procedure for Computing the Frequency of Intersection of the 
Proposed Repository by a Volcanic Event ............................................................................60 
11a. Logic Tree Structure Used to Characterize Uncertainty in Volcanic Hazard.......................62 
11b. Logic Tree Structure for Subtrees Addressing Uncertainty in Volcanic Hazard from 
Specific Sources ....................................................................................................................62 
12. Definition of Parameters Used to Compute the Probability of Intersection of the 
Proposed Repository Footprint by a Volcanic Event............................................................64 
13. Example Distributions for Dike Length, L, (part a); Normalized Location of the 
Point Volcanic Event Relative to the Total Length of the Dike, EL, (part b); and the 
Resulting Distribution for Distance from the Point Volcanic Event to the End of the 
Dike, d (part c) .....................................................................................................................65 
14. Example Simulations of the Distribution of Eruptive Centers Along the Length of a 
Dike for: (a) the Independent, Uniformly Distributed Spatial Distribution and (b) the 
Uniformly Spaced, Randomly Distributed Spatial Distribution...........................................71 
15a. Probability for the Number of Eruptive Centers Within the Proposed Repository 
Footprint, rEC, as a Function of Dike Length, L, for the Length of Intersection, LI = 1 
Kilometer and the Number of Eruptive Centers Associated with the Volcanic Event, 
nEC , = 2 ..............................................................................................................................74 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 6 September 2003 
FIGURES (Continued) 
Page 
5b. Probability for the Number of Eruptive Centers Within the Proposed Repository 
Footprint, rEC, as a Function of Dike Length, L, for the Length of Intersection, LI = 1 
Kilometer and the Number of Eruptive Centers Associated with the Volcanic Event, 
nEC , = 3 ...............................................................................................................................74 
6a. Proposed License Application Emplacement Drifts and Footprint Polygon 
Encompassing Emplacement Panels 1, 2, 3, and 5 ...............................................................78 
6b. Location of Proposed License Application Repository Footprint Compared to 
Repository Footprint Used in the Probabilistic Volcanic Hazard Analysis..........................79 
7. Spatial Distribution of Volcanic Hazard Defined by the Probabilistic Volcanic 
Hazard Analysis Expert Panel: (a) Map of Expected Volcanic Event Frequency and 
(b) Map of Spatial Disaggregation of Expected Intersection Frequency..............................84 
8. Distributions for Number of Eruptive Centers per Volcanic Event, nEC, Derived from 
the Probabilistic Volcanic Hazard Analysis Experts Interpretations (from 
Attachment III, Figure III-1) .................................................................................................86 
19. Probability for the Number of Eruptive Centers Within the Proposed Repository 
Footprint, rEC, Computed Using the Uniformly Spaced, Randomly Distributed Fixed 
Density Spatial Distribution of Eruptive Centers and for the Length of Intersection, 
LI = 1 km, and an Average Spacing of 2.5 km Between Eruptive Centers Compared 
to the Results for the IUD and USRD Models Shown in Figure 15a....................................88 
20. Annual Frequency of Intersecting the Proposed License Application Repository 
Footprint...............................................................................................................................97 
21. Marginal Distributions for Dike Intersection Length, LI, for the 5th Percentile, Mean, 
and 95th Percentile Frequency of Intersection.......................................................................99 
22. Marginal Distributions for Dike Intersection Azimuth, f, for the 5th Percentile, 
Mean, and 95th Percentile Frequency of Intersection for the Proposed License 
Application Footprint ..........................................................................................................101 
23. Marginal Distributions for the Number of Eruptive Centers Within the Proposed 
Repository Footprint, rEC, for the 5th Percentile, Mean, and 95th Percentile Frequency 
of Intersection 104 
24. Locations of Potential Buried Basalt Inferred from Aeromagnetic Data ...........................106 
25. Composite Annual Frequency of Intersection of the Repository Footprint for 
Sensitivity Cases for the Primary-plus-Contingency Block Case of the 70,000-Metric 
Tons of Uranium No-Backfill Layout ................................................................................111 
26. Individual Expert Results for Annual Frequency of Intersection of the Proposed 
Repository Footprint for Sensitivity Cases for the Primary-plus-Contingency Block 
Case of the 70,000-Metric Tons of Uranium No-Backfill Layout ......................................112 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 7 September 2003 
TABLES 
Page 
1. Software Routines Used to Compute Frequency of Intersection of the Proposed 
Repository by a Dike.............................................................................................................14 
2. Software Routines Used to Compute Conditional Distribut ions for Dike Length, 
Azimuth, and Number of Eruptive Centers Within the Proposed Repository......................15 
3. Software Routines Used to Compute Conditional Distributions for Dike Length, 
Azimuth, and Number of Eruptive Centers Within the Proposed Repository, 
Incorporating an Empirical Distribution for Average Spacing Between Eruptive 
Centers ................................................................................................................................19 
4. Software Used to Convert Emplacement Drift End Points for the Proposed LA 
Repository Footprint from Nevada State Plane Coordinates to Universal Transverse 
Mercator ..............................................................................................................................20 
5. Exempt Software...................................................................................................................20 
6. Input Data.............................................................................................................................21 
7. Other Input to This Scientific Analysis ................................................................................21 
8. Project Requirements for This Scientific Analysis Report ...................................................21 
9. Included Feature, Event, and Process for This Scientific Analysis Report and Its 
Disposition in Total System Performance Assessment for the License Application............26 
10. Estimated Volume and 40Ar/39Ar Agea of Quaternary Volcanoes in the Yucca 
Mountain Repository ............................................................................................................29 
11. Probabilistic Volcanic Hazard Analysis Panel Members .....................................................30 
12. Alternative Conceptual Models Not Cons idered in the Probabilistic Volcanic Hazard 
Analysis................................................................................................................................34 
13. Published Estimates of the Probability of Intersection of the Proposed Repository at 
Yucca Mountain by a Volcanic Event ..................................................................................37 
14. Average Eruptive Center Spacing (from Attachment III, Table III-12) ...............................87 
15. Empirical Distribution for Average Spacing Between Eruptive Centers Calculation 
Results (from Attachment III, Table III-13 of this document) .............................................93 
16. Frequency of Intersection for the License Application Footprint (Blocks 1, 2, 3, 
and 5)....................................................................................................................................95 
17. Marginal Distributions for Dike Intersection Length for the 5th Percentile, Mean, 
and 95th Percentile Frequency of Intersection of the Proposed License Application 
Footprint.............................................................................................................................100 
18. Marginal Distribution for Intersecting Dike Azimuth for the 5th Percentile, Mean, 
and 95th Percentile Frequency of Intersection of the Proposed License Application 
Footprint.............................................................................................................................102 
19. Marginal Distribution for Number of Eruptive Centers Within the Proposed 
Repository for the 5th Percentile, Mean, and 95th Percentile Frequency of 
Intersection of the Proposed License Application Footprint ..............................................104 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 8 September 2003 
TABLES (Continued) 
Page 
20. Comparison of Mean Number of Volcanic Events for 1996 Probabilistic Volcanic 
Hazard Analysis Assessment with Sensitivity Analysis Values .........................................109 
21. Summary of Computed Freque ncy of Intersection for 70,000-Metric Tons of 
Uranium No-Backfill Repository Layout (primary + contingency blocks) from 
Sensitivity Cases .................................................................................................................110 
22. Summary Frequencies of Disruptive Volcanic Events for the License Application 
Footprint.............................................................................................................................114 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 9 September 2003 
ACRONYMS AND ABBREVIATIONS 
BSC Bechtel SAIC Company, LLC 
CDF cumulative probability density function 
DOE U.S. Department of Energy 
DTN data tracking number 
FEP feature, event, and process 
IUD-C Independent, Uniformly Distributed, Correlated 
IUD-UC Independent, Uniformly Distributed, Uncorrelated 
LA License Application 
MTU metric tons of uranium 
m.y. million years 
NRC U.S. Nuclear Regulatory Commission 
PA performance assessment 
PVHA probabilistic volcanic hazard analysis 
STN software tracking number 
SR site recommendation 
TSPA total system performance assessment 
TWP technical work plan 
USGS U.S. Geological Survey 
USRD-C Uniformly Spaced, Randomly Distributed, Correlated 
USRD-FD Uniformly Spaced, Randomly Distributed Fixed Density 
USRD-UC Uniformly Spaced, Randomly Distributed, Uncorrelated 
UTM Universal Transverse Mercator 
YMR Yucca Mountain region 
YMRP Yucca Mountain Review Plan, Final Report 

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INTENTIONALLY LEFT BLANK

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ANL-MGR-GS-000001 REV 01 11 September 2003 
1. PURPOSE 
The purpose of this scientific analysis report is threefold. 
Present a conceptual framework of igneous activity in the Yucca Mountain region (YMR) 
consistent with the volcanic and tectonic history of this region and the assessment of this history 
by experts who participated in the probabilistic volcanic hazard analysis (PVHA) (CRWMS 
M&O 1996 [100116]*). Conceptual models presented in the PVHA are summarized and applied 
in areas in which new information has been presented. Alternative conceptual models are 
discussed as well as their impact on probability models. The relationship between volcanic 
source zones defined in the PVHA and structural features of the YMR are described based on 
discussions in the PVHA and studies presented since the PVHA. 
Present revised probability calculations, based on PVHA outputs, for the repository footprint 
currently proposed for the License Application (LA), rather than the footprint used at the time of 
the PVHA. This analysis report also calculates the probability of an eruptive center(s) forming 
within the current repository footprint using information developed in the PVHA. Probability 
distributions are presented for the length and orientation of volcanic dikes located within the 
repository footprint and for the number of eruptive centers (conditional on a dike intersecting the 
repository) located within the repository footprint. 
Document sensitivity studies that analyze how the presence of potentially buried basaltic 
volcanoes impact the frequency of intersection of the proposed repository footprint by a basaltic 
dike. The sensitivity study was prompted by aeromagne tic data collected in 1999 indicating the 
possible presence of previously unrecognized buried volcanoes in the YMR (Blakely et al. 2000 
[151881]; OLeary et al. 2002 [158468]). 
The U.S. Department of Energy (DOE) considers volcanism to be a potentially disruptive event 
in the total system performance assessment (TSPA) analysis supporting the LA for the proposed 
Yucca Mountain repository (DOE 1998 [100550]). The two volcanic scenarios (with individual 
probabilities and consequences) being modeled by the TSPA-LA are: (1) the ascent of a basaltic 
dike or dike system (i.e., a set or swarm of multiple dikes comprising a single intrusive event) to 
repository level where it intersects drifts; and (2) the development of a volcano within the 
repository footprint with one or more conduits that intersect waste packages. As a consequence 
of the first event, which is noneruptive, waste from breached packages may provide a source of 
radionuclides when groundwater moves through the damaged packages at some time in the 
future (igneous intrusion groundwater release). The potential consequence of the second event is 
that waste packages entrained within a conduit may be breached, releasing radionuclides to the 
erupting ash plume where they can be dispersed downwind to a reasonably maximally exposed 
individual (10 CFR 63 [156605], Section 63.2; 66 FR 55794) in the accessible environment at 
the controlled area boundary (10 CFR 63 [156605], Section 63.302; 66 FR 55813). According to 
10 CFR Part 63 this location is to be approximately 18 kilometers (km) south of the repository. 
* In this report, a unique six-digit numerical identifier (the Document Input Reference System [DIRS] number) is placed in the 
text following the reference callout (e.g., BSC 2002 [155950]), the purpose of which is to assist the reader in locating a 
specific reference in the DIRS database. Within the reference list (Section 8), multiple sources by the same author and date 
(e.g., BSC2002) are sorted alphabetically by title. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 12 September 2003 
The TSPA-LA requires consideration of both probability and consequence. The objective of the 
PVHA was to determine the probability of a basaltic dike intersecting the proposed repository 
(CRWMS M&O 1996 [100116]). The PVHA report was the outcome of an expert elicitation 
and forms the foundation of much of the igneous analysis for the LA. The PVHA included 
discussion of some aspects of the consequences of a volcanic event but not all the aspects 
required for the present analysis; therefore, additional analyses will be performed to support 
description of the volcanic risk. The risk from volcanism will be described by combining work 
from the PVHA (probability) and the present enhanced analysis of consequence. 
This report, Characterize Framework for Igneous Activity at Yucca Mountain, Nevada, 
Revision 01, describes the conceptual framework for volcanism near Yucca Mountain and how 
the conceptual framework provides the basis for probability calculations. This report also 
presents the probability results and associated uncertainties for intersection of the proposed 
repository by a volcanic event and the probability of an eruption through the repository, 
conditional on a dike intersection. In the context of the PVHA, a volcanic event is a spatially 
and temporally distinct batch of magma ascending from the mantle through the crust as a dike or 
system of dikes (CRWMS M&O 1996 [100116], Appendix E). For the purposes of the 
probability models discussed in this report, a volcanic event is defined as a point (x,y) in space 
representing the expected midpoint of the dike system involved in the magma ascent. The dike 
system associated with the volcanic event is represented in probability model by a line element 
defined in terms of a length, azimuth and location relative to the point event (Figures 10 and 12). 
The term dike length used in the PVHA and in this report when discussing volcanic events, 
refers to the total length of the dike system associated with the volcanic event. The phrase 
intersection of the repository footprint by a dike refers to intersection of the emplacement area of 
the repository by the line element representing the dike system associated with the volcanic 
event. The possibility that a dike system (e.g., multiple dikes) has width or consists of multiple 
parallel dikes does not significantly affect the intersection probability and is not part of the 
calculations in this report. The width of the dikes and the number of parallel dikes does affect 
the consequences of an intersection and is included in Number of Waste Packages Hit by Igneous 
Intrusion (BSC 2003 [161851]). 
The probability results documented in this report provide the basis for all further igneous 
consequence analysis. This report also provides direct input into the Number of Waste Packages 
Hit by Igneous Intrusion scientific analysis report, Number of Waste Packages Hit by Igneous 
Intrusion (BSC 2003 [161851]), and direct input to the TSPA-LA. 
A recalculation of the volcanic hazard using the current proposed LA repository layout 
(BSC 2003 [162289]) is documented in this report. The current revision of this report 
(Revision 01) uses the same approach for calculation of the conditional number of eruptive 
centers occurring within the repository footprint that was used in the previous revision (CRWMS 
M&O 2000 [151551]). This approach is to calculate the conditional number of eruptive centers 
occurring within the repository footprint using empirical distributions for the average spacing 
between eruptive centers rather than the just the expected values of these distributions and to 
incorporate uncertainty in the effect of the repository opening on the conditional probability of 
the occurrence of an eruptive center within the repository footprint. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 13 September 2003 
Consideration of the number of volcanic events that have occurred during selected periods of 
time in the YMR was one of the key parameters the PVHA used to calculate the probability of a 
basaltic dike intersecting the repository footprint. Volcanic features counted as volcanic events 
included individual volcanoes, alignments of volcanoes, and aeromagnetic anomalies in the 
region that are known (by drilling), or inferred to be, buried volcanoes. In 1999, three years after 
the PVHA was completed, a new aeromagnetic survey of the YMR was completed under the 
direction of the U.S. Geological Survey (USGS) (Blakely et al. 2000 [151881], OLeary et al. 
2002 [158468]). This report assesses the impact of new aeromagnetic data on the probability of 
intersection of the repository footprint by a basaltic dike using sensitivity studies that incorporate 
alternative conceptual models. 
This report is governed by the OCRWM Technical Work Plan For: Igneous Activity Analysis for 
Disruptive Events, (BSC 2002 [161315]), Work Package ADEM03. The technical work plan 
(TWP) specifies the activities to be carried out in updating information in the revision of this 
report. The activities documented in this report do not deviate from those specified in the TWP. 
2. QUALITY ASSURANCE 
Development of this scientific analysis report and the supporting analyses have been determined 
to be subject to the Yucca Mountain Projects quality assurance program (BSC 2002 [161315], 
Section 8.1, Work Package ADEM03). Approved quality assurance procedures identified in the 
TWP (BSC 2002 [161315], Section 4) have been used to conduct and document the activities 
described in this report. The TWP also identifies the methods used to control the electronic 
management of data (BSC 2002, Section 8.4 [161315]). 
An evaluation conducted per AP-SV.1Q, Control of the Electronic Management of Information, 
identifies that electronic data requiring controls are involved in this work (see Attachment 1, 
Office of Civilian Radioactive Waste Management Process Control Evaluation for 
Supplement V). Checksums and parity checks performed by computer operating systems 
during data transfer and storage using commonly available software and hardware, plus 
established computer security mechanisms, provide adequate assurance of the integrity of 
transferred data. Additional controls on electronic storage and transfer of data will be described 
in scientific notebooks documenting the work if scientific notebooks are used. 
3. USE OF SOFTWARE 
3.1 SOFTWARE TRACKED BY CONFIGURATION MANAGEMENT 
The calculations presented in this scientific analysis report were performed with the set of 
software routines described below. This software has been qualified following procedure 
AP-SI.1Q, Software Management. The software and routines used in support of this work are 
appropriate for this application and are used within their range of validation as described in the 
qualification documentation. The software is written in FORTRAN77 and operates on a 
personal computer equipped with a 486 or Pentium processor under disk operating system or in a 
Windows Microsoft disk operating system window. The computations using these software 
routines were performed using the software routines acquired from Software Configuration 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 14 September 2003 
Management. The software was designed to perform the calculations defined by the PVHA 
(CRWMS M&O 1996 [100116]) and was used within the parameter limits defined by the 
PVHA. 
3.1.1 Software Routines 
The software routine titles are listed with the .FOR extension in the Software Configuration 
Management database, the DIRS database, and in Section 8.3 of this report. The routines are 
listed by their titles without the .FOR extension in Tables 1 and 2, Figures 1 and 2, and in the 
text of this report. 
Table 1 lists the software routines used to compute the frequency of intersection of the repository 
footprint by a volcanic event through full enumeration of the PVHA experts logic trees. 
Figure 1 shows the data flow through the routines in Table 1. The software routines listed in 
Table 1 are qualified versions of the routines used in the PVHA calculation (CRWMS 
M&O 1996 1[00116]). 
Table 1. Software Routines Used to Compute Frequency of Intersection of the Proposed Repository by 
a Dike 
Software Routine 
software tracking 
number (STN) Function 
FITCD V1.0 
(10262-1.0-00) [148532] 
Computes discrete cumulative probability distributions for dike length from cumulative 
probabilities specified at selected values of length. 
SFCD V1.0 
(10275-1.0-00) [148533] 
Computes discrete cumulative probability distributions for dike length using userspecified 
distribution forms. 
DCPELD V1.0 
(10258-1.0-00) [148534] 
Computes discrete probability distribution for dike length from expert-specified 
distributions (output of FITCD). 
CPDI V1.0 
(10257-1.0-00) [148535] 
Computes conditional probability of intersection from volcanic events on a x,y grid 
using output of DCPELD and expert-specified azimuth distributions. 
UZVH V1.0 
(10277-1.0-00) [148536] 
Computes frequency of intersection from volcanic source zones using output of CPDI. 
FKVH V1.0 
(10265-1.0-00) [148567] 
Computes frequency of intersection using kernel density estimation with specified h 
and output of CPDI. 
UZVPVH V1.0 
(10279-1.0-00) [148537] 
Computes frequency of intersection from volcanic source zones using volume 
predictable volcanic event rate model and output of CPDI. 
FKVPVH V1.0 
(10267-1.0-00) [148538] 
Computes frequency of intersection using kernel density estimation using volume 
predictable volcanic event rate model and output of CPDI. 
ZBCKVH V1.0 
(10283-1.0-00) [148539] 
Computes frequency of intersection using kernel density estimation with h constrained 
by a source zone boundary and output of CPDI. 
FITFIELD V1.0 
(10263-1.0-00) [148540] 
Computes parameters of a bivariate Gaussian distribution that approximates 
boundaries of a defined polygon. 
FIT2CNTR V1.0 
(10261-1.0-00) [148541] 
Computes parameters of a bivariate Gaussian distribution from locations of volcanic 
events. 
PFGVH V1.0 
(10273-1.0-00) [148542] 
Computes frequency of intersection using a bivariate Gaussian distribution with 
specified field parameters and output of CPDI. Bivariate Gaussian distribution 
parameters obtained from programs FIT2CNTR or FITFIELD. 
FPFGVH V1.0 
(10269-1.0-00) [148543] 
Computes frequency of intersection using a bivariate Gaussian distribution with 
parameters fit to volcanic event locations and output of CPDI. 
VHTREE V1.0 
(10282-1.0-00) [148544] 
Computes mean and fractiles of frequency of intersection over an individual experts 
volcanic hazard logic tree and aggregate over all experts using outputs of UZVH, 
UZVHB, FKVH, UZVPVH, FKVPVH, ZBCLVH, PFGVH, and FPFGVH. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 15 September 2003 
N/A-For Illustration Purposes Only 
NOTE: Names in the boxes denote software routines listed in Table 1. 
Figure 1. Flowchart for Computation of Frequency of Intersection of Proposed Repository by a Dike 
Table 2 lists the software routines used to compute the conditional distributions for the length 
and azimuth of an intersecting dike within the proposed repository footprint and the number of 
eruptive centers within this footprint. The data flow through the software routines for this 
calculation is shown in Figure 2. 
Table 2. Software Routines Used to Compute Conditional Distributions for Dike Length, Azimuth, and 
Number of Eruptive Centers Within the Proposed Repository 
Software Routine 
(STN Number) Function 
FITCD V1.0 
(10262-1.0-00) [148532] 
Computes discrete cumulative probability distributions for dike length from 
cumulative probabilities specified at selected values of length. 
SFCD V1.0 
(10275-1.0-00) [148533] 
Computes discrete cumulative probability distributions for dike length using 
user-specified distribution forms. 
DCPELD V1.0 
(10258-1.0-00) [148534] 
Computes discrete probability distribution for dike length from expert-specified 
distributions (output of FITCD). 
CPDI V1.0 
(10257-1.0-00) [148535] 
Computes conditional probability of intersection from volcanic events on a x,y 
grid using output of DCPELD and expert-specified azimuth distributions. 
UZVHLH V1.0 
(10278-1.0-00) [148545] 
Computes simulations of contributions to frequency of intersection on a x,y 
grid from volcanic source zones using Latin Hypercube sampling and output 
from CPDI. 

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ANL-MGR-GS-000001 REV 01 16 September 2003 
Table 2. Software Routines Used to Compute Conditional Distributions for Dike Length, Azimuth, and 
Number of Eruptive Centers Within the Proposed Repository (Continued) 
Software Routine 
(STN Number) Function 
FKVHLH V1.0 
(10266-1.0-00) [148546] 
Computes simulations of contributions to frequency of intersection on an x,y 
grid using kernel density estimation with specified h , Latin Hypercube 
sampling, and output from CPDI. 
UZVPVHLH V1.0 
(10280-1.0-00) [148547] 
Computes simulations of contributions to frequency of intersection on an x,y 
grid from volcanic source zones using volume predictable volcanic event rate 
model, Latin Hypercube sampling, and output from CPDI. 
FKVPVHLH V1.0 
(10268-1.0-00) [148551] 
Computes simulations of contributions to frequency of intersection on an x,y 
grid with kernel density estimation using volume predictable volcanic event 
rate model, Latin Hypercube sampling, and output from CPDI. 
ZBCKVHLH V1.0 
(10284-1.0-00) [148550] 
Computes simulations of contributions to frequency of intersection on an x,y 
grid using kernel density estimation with h constrained by a source zone 
boundary, Latin Hypercube sampling, and output from CPDI. 
FITFIELD V1.0 
(10263-1.0-00) [148540] 
Computes parameters of a bivariate Gaussian distribution that approximates 
boundaries of a defined polygon. 
FIT2CNTR V1.0 
(10261-1.0-00) [148541] 
Computes parameters of a bivariate Gaussian distribution from locations of 
volcanic events. 
PFGVHLH V1.0 
(10274-1.0-00) [148552] 
Computes simulations of contributions to frequency of intersection on a x,y 
grid using a 2-D-Gaussian distribution with specified parameters, Latin 
Hypercube sampling, and output from CPDI. Gaussian distribution parameters 
obtained from programs FIT2CNTR or FITFIELD. 
FPFGVHLH V1.0 
(10270-1.0-00) [148553] 
Computes simulations of contributions to frequency of intersection on an x,y 
grid using a 2-D-Gaussian distribution with parameters fit to volcanic event 
locations, Latin Hypercube sampling, and output from CPDI. 
VHTIELHS V1.0 
(10281-1.0-00) [148554] 
Computes mean and fractiles of simulations of contributions to frequency of 
intersection on an x,y grid over an individual experts volcanic hazard logic tree 
using Latin Hypercube sampling and output from UZVHLH, FKVHLH, 
UZVPVHLH, FKVPVHLH, ZBCLVHLH, PFGVHLH, and FPFGVHLH. 
NECPDS V1.0 
(10272-1.0-00) [148555] 
Computes distributions for number of eruptive centers per volcanic event and 
average spacing between eruptive centers. 
SFIDSR V1.0 
(10276-1.0-00) [148571] 
Computes discrete incremental probability distributions for dike length using 
input to SFCD. 
DLECD V1.0 
(10260-1.0-00) [148558] 
Computes joint discrete probability distributions for dike length and number of 
eruptive centers per volcanic event using output from FITIDSR. 
DILECDLH V1.0 
(10259-1.0-00) [148559] 
Computes joint conditional distribution of dike intersection length, dike azimuth, 
and number of eruptive centers within the repository footprint from outputs of 
program VHTIELHS using Latin hypercube sampling of dike length and 
volcanic event location distributions from DIECDIST. 
CFRAC V1.0 
(10254-1.0-00) [148560] 
Locates individual experts sim ulation results that represent specified 
percentiles of the composite distribution for frequency of intersection from 
outputs of VHTIELHS. 
COMBSM V1.0 
(10256-1.0-00) [148561] 
Computes composite joint distribution of dike intersection length, dike azimuth, 
and number of eruptive centers within the repository footprint across experts 
from outputs of DILECDLH and VHTIELHS for mean hazard. 
COMBSF V1.0 
(10255-1.0-00) [148562] 
Computes composite joint distribution of dike intersection length, dike azimuth, 
and number of eruptive centers within the repository footprint across experts 
from outputs of DILECDLH for selected percentiles of the hazard. 
MARGIN V1.0 
(10271-1.0-00) [148563] 
Computes marginal distributions for dike intersection length, dike azimuth, and 
number of eruptive centers within the repository footprint from output of 
COMBSM and COMBSF. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 17 September 2003 
In addition, the software routine COMBDELD V1.0 (STN: 102881.0-00 [148617]) was used to 
calculate aggregate dike length and event length distributions across all 10 PVHA experts for 
display in Figures 4 and 6. 
3.1.2 Software Used in the Current Revision of this Scientific Analysis 
The current revision of this scientific analysis (Revision 01) re-computes the probability 
distributions for frequency of intersection of the repository footprint using the current proposed 
LA repository footprint (BSC 2003 [162289]). This calculation is performed using the software 
routines listed in Table 1. Revision 01 also re-computes the conditional probability for length 
and azimuth of intersecting dikes and the number of eruptive centers within the repository 
footprint. These calculations are performed using the software routines listed in Table 3. Five of 
the software routines in Table 3 are modified from those listed in Table 2 to incorporate the 
empirical distribution for the average spacing between eruptive centers. Software used to 
convert Nevada State Plane coordinates to Universal Transverse Mercator (UTM) coordinates 
for the proposed LA footprint is listed in Table 4. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 18 September 2003 
N/A-For Illustration Purposes Only 
NOTE: Names in boxes denote software routines listed in Table 2. 
Figure 2. Flowchart for Computation of Conditional Distributions for Length and Azimuth of Intersecting 
Dike and Number of Eruptive Centers Within the Proposed Repository Given Intersection of 
This Footprint by a Dike 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 19 September 2003 
Table 3. Software Routines Used to Compute Conditional Distributions for Dike Length, Azimuth, and 
Number of Eruptive Centers Within the Proposed Repository, Incorporating an Empirical 
Distribution for Average Spacing Between Eruptive Centers 
Software Routine 
(STN Number) Function 
FITCD V1.0 
(10262-1.0-00) [148532] 
Computes discrete cumulative probability distributions for dike length from 
cumulative probabilities specified at selected values of length. 
SFCD V1.0 
(10275-1.0-00) [148533] 
Computes discrete cumulative probability distributions for dike length using userspecified 
distribution forms. 
DCPELD V1.0 
(10258-1.0-00) [148534] 
Computes discrete probability distribution for dike length from expert-specified 
distributions (output of FITCD). 
CPDI V1.0 
(10257-1.0-00) [148535] 
Computes conditional probability of intersection from volcanic events on a x,y grid 
using output of DCPELD and expert-specified azimuth distributions. 
UZVHLH V1.0 
(10278-1.0-00) [148546] 
Computes simulations of contributions to frequency of intersection on a x,y grid 
from volcanic source zones using Latin Hypercube sampling and output from CPDI. 
FKVHLH V1.0 
(10266-1.0-00) [148545] 
Computes simulations of contributions to frequency of intersection on an x,y grid 
using kernel density estimation with specified h , Latin Hypercube sampling, and 
output from CPDI. 
UZVPVHLH V1.0 
(10280-1.0-00) [148547] 
Computes simulations of contributions to frequency of intersection on an x,y grid 
from volcanic source zones using volume predictable volcanic event rate model, 
Latin Hypercube sampling, and output from CPDI. 
FKVPVHLH V1.0 
(10268-1.0-00) [148551] 
Computes simulations of contributions to frequency of intersection on an x,y grid 
with kernel density estimation using volume predictable volcanic event rate model, 
Latin Hypercube sampling, and output from CPDI. 
ZBCKVHLH V1.0 
(10284-1.0-00) [148550] 
Computes simulations of contributions to frequency of intersection on an x,y grid 
using kernel density estimation with h constrained by a source zone boundary, 
Latin Hypercube sampling, and output from CPDI. 
FITFIELD V1.0 
(10263-1.0-00) [148540] 
Computes parameters of a bivariate Gaussian distribution that approximates 
boundaries of a defined polygon. 
FIT2CNTR V1.0 
(10261-1.0-00) [148541] 
Computes parameters of a bivariate Gaussian distribution from locations of 
volcanic events. 
PFGVHLH V1.0 
(10274-1.0-00) [148552] 
Computes simulations of contributions to frequency of intersection on a x,y grid 
using a 2D-Gaussian distribution with specified parameters, Latin Hypercube 
sampling, and output from CPDI. Gaussian distribution parameters obtained from 
programs FIT2CNTR or FITFIELD. 
FPFGVHLH V1.0 
(10270-1.0-00) [148553] 
Computes simulations of contributions to frequency of intersection on an x,y grid 
using a 2D-Gaussian distribution with parameters fit to volcanic event locations, 
Latin Hypercube sampling, and output from CPDI. 
VHTIELHS V1.0 
(10281-1.0-00) [148554] 
Computes mean and fractiles of simulations of contributions to frequency of 
intersection on an x,y grid over an individual experts volcanic hazard logic tree 
using Latin Hypercube sampling and output from UZVHLH, FKVHLH, UZVPVHLH, 
FKVPVHLH, ZBCLVHLH, PFGVHLH, and FPFGVHLH. 
NECPDS V1.1 
(10272-1.1-00) [148555] 
Computes distributions for number of eruptive centers per volcanic event and 
average spacing between eruptive centers. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 20 September 2003 
Table 3. Software Routines Used to Compute Conditional Distributions for Dike Length, Azimuth, and 
Number of Eruptive Centers Within the Proposed Repository, Incorporating an Empirical 
Distribution for Average Spacing Between Eruptive Centers (Continued) 
Software Routine 
(STN Number) Function 
FITIDSR V1.0 
(10264-1.0-00) [148557] 
Computes discrete incremental probability distributions for dike length using input 
to FITCD. 
SFIDSR V1.0 
(10276-1.0-00) [148571] 
Computes discrete incremental probability distributions for dike length using input 
to SFCD 
DLECD V1.0 
(10260-1.0-00) [148558] 
Computes joint discrete probability distributions for dike length and number of 
eruptive centers per volcanic event using output from FITIDSR 
DILECDLH V1.1 
(10259-1.1-00) [148559] 
Computes joint conditional distribution of dike intersection length, dike azimuth, and 
number of eruptive centers within the repository footprint from outputs of program 
VHTIELHS using Latin hypercube sampling of dike length and volcanic event 
location distributions from DIECDIST 
CFRAC V1.0 
(10254-1.0-00) [148560] 
Locates individual experts simulation results that represent specified percentiles of 
the composite distribution for frequency of intersection from outputs of VHTIELHS 
COMBSM V1.1 
(10256-1.1-00) [148561] 
Computes composite joint distribution of dike intersection length, dike azimuth, and 
number of eruptive centers within the repository footprint across experts from 
outputs of DILECDLH and VHTIELHS for mean hazard 
COMBSF V1.1 
(10255-1.1-00) [148562] 
Computes composite joint distribution of dike intersection length, dike azimuth, and 
number of eruptive centers within the repository footprint across experts from 
outputs of DILECDLH for selected percentiles of the hazard 
MARGIN V1.1 
(10271-1.1-00) [148563] 
Computes marginal distributions for dike intersection length, dike azimuth, and 
number of eruptive centers within the repository footprint from output of COMBSM 
and COMBSF 
Table 4. Software Used to Convert Emplacement Drift End Points for the Proposed LA Repository 
Footprint from Nevada State Plane Coordinates to Universal Transverse Mercator 
Software Name 
and Version (V) STN Description 
Computer and Platform 
Identification 
EarthVision 5.1 
[152614] 
10174-5.1-00 Commercial GIS software used for 
coordinate conversion 
Silicon Graphics/ 
IRIX 6.5 
3.2 EXEMPT SOFTWARE 
Commercial, off-the-shelf software used in support of this scientific analysis is listed in Table 5. 
This software is exempt from the requirements of AP-SI.1Q, Software Management. 
Table 5. Exempt Software 
Software Name 
and Version 
(V) STN Description 
Computer and 
Platform 
Identification 
Microsoft Excel, 
97 
N/A The commercial software, Microsoft Excel, 97 was 
used for plotting graphs and preparing tables. No 
software routines or macros were used with this 
software to prepare this report. The output was 
visually checked for correctness. 
PC, Windows 98 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 21 September 2003 
4. INPUTS 
4.1 DATA AND PARAMETERS 
The location, a brief description, and the data tracking numbers (DTNs) used as input for this 
scientific analysis report are listed in Table 6. The qualification status of data input is indicated 
in the electronic DIRS database. 
The source of input data for this analysis is the PVHA expert interpretations presented in 
Probabilistic Volcanic Hazard Analysis for Yucca Mountain, Nevada (CRWMS M&O 1996 
[100116]). Because this report is an analysis of the PVHA (CRWMS M&O 1996 [100116]), the 
use of the PVHA as input to this report is appropriate. The PVHA expert interpretations are used 
as inputs to the calculations described in Section 6.5 and Attachment III. The interpretations are 
also discussed in the conceptual framework described in Sections 6.1 through 6.4. 
Table 6. Input Data 
Data Name Data Source DTN 
PVHA (CRWMS M&O 1996 [100116]): 
Expert Assessment of Volcanic Hazard 
in the YMR 
CRWMS M&O 1996 [100116] MO0002PVHA0082.000 
[148234] 
Other input to this analysis is listed in Table 7. 
Table 7. Other Input to This Scientific Analysis 
Name Description Uncertainty 
LA repository footprint Repository footprint determined from information described 
in BSC (2003 [162289]) 
N/A 
All other DTNs presented in this scientific analysis report are not used as direct input to this 
report and are used as reference only. 
4.2 CRITERIA 
The Yucca Mountain Projects Requirements Document (Canori and Leitner 2003 [161770]) 
identifies the high-level requirements for the Project. The requirements that pertain to this 
scientific analysis report, and its link to 10 CFR Part 63 [156605], are shown in Table 8. 
Table 8. Project Requirements for This Scientific Analysis Report 
Requirement 
Number Title 
10 CFR Part 63 
link [156605] 
Yucca Mountain Review 
Plan, Final Report (YMRP) 
(NRC 2003 [163274]) 
Acceptance Criteria 
PRD-002/T-015 Requirements for Performance Assessment 
(PA) 
10 CFR 63.114 2.2.1.3.10.3, criteria 1 to 3 

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ANL-MGR-GS-000001 REV 01 22 September 2003 
The YMRP (NRC 2003 [163274]) lists acceptance criteria pertaining to the above requirements. 
Criteria that are applicable to this scientific analysis report are described in Attachment I. 
The YMRP Acceptance Criteria are intended to assure that the requirements at 
10 CFR 63.114(a)(c) and (e)(g) [156605] are met. 
4.3 CODES AND STANDARDS 
No specific formally established codes or standards have been identified as applying to this 
activity. This activity does not directly support LA design. 
5. ASSUMPTIONS 
This section describes the assumptions used for the analyses in Section 6.5 and Attachment III. 
The calculation of the updated distribution for frequency of intersection of the proposed 
repository footprint by a basaltic dike requires no assumptions because it uses the outputs 
defined by the PVHA (CRWMS M&O 1996 [100116]) without modification. The update 
involves only a change in the proposed repository footprint. 
The calculation of conditional distributions for the length and azimuth of intersecting dikes 
within the proposed repository requires no assumptions because it involves only a modification 
of the software to output an intermediate step of the frequency of intersection of the proposed 
repository footprint by a dike calculation. 
The calculation of conditional distributions for the number of eruptive centers within the 
proposed repository footprint requires an assessment of the number of eruptive centers associated 
with a volcanic event and the spatial distribution for eruptive centers along the length of the dike. 
As explained in Section 6.5.2.2, this analysis uses the PVHA experts assessment of volcanic 
event counts and the number of separate eruptive centers to develop a distribution for the number 
of eruptive centers per volcanic event. The number of eruptive centers associated with a 
volcanic event is derived using the following assumptions. 
5.1 USE OF QUATERNARY VOLCANOES 
Assumption: The mapped Quaternary volcanoes in the YMR are representative of the type 
being characterized for calculation of the consequences of an eruptive event through the 
proposed repository. For the purposes of this analysis report and for PA calculations, each 
eruptive center or vent equates to one subsurface conduit. 
Basis: The characteristics of Quaternary volcanoes in the YMR are used to define the 
distributions for the characteristics of future volcanic events (BSC 2003 [161838]). 
The assumption that each volcano is associated with a conduit is consistent with the description 
of the eruptive process for YMR volcanoes described in Characterize Eruptive Processes at 
Yucca Mountain, Nevada (BSC 2003 [161838]). Volcanoes were also used by the PVHA 
experts as indicators of the occurrence of past volcanic events. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 23 September 2003 
Use in the Analysis: This assumption is used in Attachment III to derive distributions for the 
number of eruptive centers per volcanic event and the average spacing between eruptive centers. 
Confirmation Status : This assumption needs no further confirmation. 
5.2 ALL VOLCANIC EVENTS PRODUCE AT LEAST ONE ERUPTIVE CENTER 
Assumption: Each hypothetical volcanic event for which the associated dike intersects the 
repository has at least one eruptive center located somewhere along the length of the dike. 
Basis: This assumption is justified on the basis of the PVHA expert panels general belief that 
magma that ascends to within a few hundred meters of the surface will produce a surface 
manifestation of the volcanic event (CRWMS M&O 1996 [100116], Appendix E, 
e.g., pp. RC-10, BC-6, WD-6, WH-6, MK-12). The assumption is conservative in that the 
PVHA experts allowed for the possibility that not all past volcanic events reached the surface in 
assessing the rate of volcanic events. The rate of volcanic events used to compute the frequency 
of intersection of the proposed repository footprint by a dike was obtained by multiplying the 
rate based on past volcanic events with observed surface manifestations by a hidden events 
factor greater than or equal to 1.0. Assuming all future volcanic events will produce an eruptive 
center produces the maximum rate of eruptive center occurrence. 
Use in the Analysis: This assumption is used in Attachment III to develop distributions for the 
number of eruptive centers per volcanic event and in Section 6.5.2.2 in the computation of the 
conditional distribution for number of eruptive centers within the repository. 
Confirmation Status: The assumption is consistent with the expert panels general 
consideration that magma ascending to within a few hundred meters of the surface would erupt 
and need not be confirmed. 
5.3 LOCATION OF ERUPTIVE CENTERS ALONG THE LENGTH OF A DIKE OR 
DIKE SEGMENT 
Assumption: The location of an eruptive center along the length of a dike or dike segment is 
defined by a uniform probability distribution. 
Basis: This assumption is justified on the basis that it is the minimum information assumption 
that maximizes the uncertainty in location of the eruptive center. Any other form of a probability 
distribution requires more information than the range of possible locations (in this case, the end 
points of a dike or dike segment). The assumption is conservative because it maximizes the 
probability for the occurrence of multiple eruptive centers within the proposed repository. 
Use in the Analysis : This assumption is used in Section 6.5.2.2 in the computation of the 
conditional distribution for number of eruptive centers within the proposed repository. 
Confirmation Status : The assumption does not need to be confirmed because it does not 
impose any additional information beyond the length of the dike, which is obtained from the 
PVHA experts interpretations. Furthermore, in this report an alternative assumption is used in 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 24 September 2003 
which the presence of the repository cavity results in a probability of 1.0 of at least one eruptive 
center, given an intersection by a volcanic event. 
6. SCIENTIFIC ANALYSIS 
6.1 INTRODUCTION 
In this report, a conceptual framework for volcanism at Yucca Mountain consistent with output 
and results of the PVHA is described. This report describes how this framework and alternative 
conceptual frameworks influence the results of estimations of the probability of dike intersection 
and volcanic eruption at the proposed geologic repository at Yucca Mountain. 
This report summarizes and extends the findings of the PVHA (CRWMS M&O 1996 [100116]). 
For the PVHA, an expert panel was convened in 1995 to review all pertinent data relating to 
volcanism at Yucca Mountain and, based on these data, to quantify both the annual probability 
and associated uncertainty of a volcanic event intersecting a proposed repository sited at Yucca 
Mountain. The data the experts reviewed was comprehensive, consisting of two decades of data 
collected by volcanologists who conducted studies to quantify the probability that a future 
volcanic eruption would disrupt the proposed repository (e.g., CRWMS M&O 1998 [105347] 
and references therein). This report also describes the relationship between volcanic source 
zones defined in the PVHA and the current understanding of structural controls on volcanism in 
the YMR. 
The results of the PVHA are a set of alternative models for assessing the volcanic hazard at 
Yucca Mountain, probabilities that each model is the appropriate model, and probability 
distributions for the parameters of the models. As such, the PVHA defines the scientific 
uncertainty in applying models to assess the volcanic hazard. The PVHA experts documented 
the basis for their assessments of the validity of the alternative models in Probabilistic Volcanic 
Hazard Analysis for Yucca Mountain, Nevada (CRWMS M&O 1996 [100116], Appendix E). 
Therefore, the results of the PVHA are considered valid for assessing the uncertainty in the 
volcanic hazard at Yucca Mountain. 
In the context of the PVHA the volcanic hazard is defined as the annual frequency of intersection 
of the repository by a volcanic event. A volcanic event was defined in the PVHA to be a 
spatially and temporally distinct batch of magma ascending from the mantle through the crust as 
a dike or system of dikes (CRWMS M&O 1996 [100116], Appendix E). For the purposes of the 
probability models developed in the PVHA and discussed in this report, a volcanic event is 
defined as a point (x,y) in space representing the expected midpoint of the dike system involved 
in the magma ascent. The dike system associated with the volcanic event is represented in 
probability model by a line element defined in terms of a length, azimuth and location relative to 
the point event. The term dike length used in the PVHA and in this report when discussing 
volcanic events, refers to the total length of the dike system associated with the volcanic event. 
The phrase intersection of the repository footprint by a dike refers to intersection of the 
emplacement area of the repository by the line element representing the dike system associated 
with the volcanic event. The possibility that a dike system (e.g., multiple dikes) has width or 
consists of multiple parallel dikes does not significantly affect the intersection probability and is 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 25 September 2003 
not part of the calculations in this report. The width of the dikes and the number of parallel dikes 
does affect the consequences of an intersection and is included in the consequence analyses 
presented in Number of Waste Packages Hit by Igneous Intrusion (BSC 2003 [161851]). 
Based on the PVHA outputs and assumptions in Section 5 of this report, probability distributions 
are developed for the length and orientation of intersecting dikes within the proposed repository 
footprint and for the number of eruptive centers located within the repository footprint 
(conditional on a dike intersecting the repository). Lastly, the probability of dike intersection is 
recalculated based on the current proposed repository footprint, and the probability of an eruptive 
center(s) forming within the current proposed repository footprint is calculated (the latter is a 
calculation that was not included in the PVHA). 
6.1.1 Features, Events, and Processes 
The development of a comprehensive list of feature, event, and process (FEPs) potentially 
relevant to postclosure performance of the proposed Yucca Mountain repository is an ongoing, 
iterative process based on site-specific information, design, and regulations. The approach for 
developing an initial list of FEPs in support of the TSPA-for the site recommendation (SR) 
(CRWMS M&O 2000 [153246]) was documented in Freeze et al. (2001 [154365]). The initial 
FEPs list contained 328 FEPs, of which 176 were included in TSPA-SR models (CRWMS 
M&O 2000 [153246], Tables B-9 through B-17). To support the TSPA-LA, the FEPs list was 
reevaluated in accordance with the Enhanced FEP Plan (BSC 2002 [158966], Section 3.2). 
Tables 2 and 3 of the TWP for igneous activity analysis (BSC 2002 [161315]) provide a listing 
of both included and excluded FEPs for each of the disruptive events analysis and model reports. 
One FEP that was listed as included in the TWP, 1.2.04.01.00 Igneous Activity, was deleted 
during the FEPs review for TSPA-LA and conducted as part of the Enhanced FEPs Plan. 
The description of the FEP was found to be entirely redundant with more specific igneous related 
FEPs. The FEPs 1.2.04.02.0A, Igneous Activity Causes Changes to Rock Properties, and 
1.2.10.02.00, Hydrologic Response to Igneous Activity, were previously, and continue to be, 
excluded. The technical basis for exclusion of these FEPs was previously provided in (CRMWS 
M&O 2000 [151553]). Although this analysis report may provide information cited in the 
technical basis for exclusion, the following discussion addresses only implementation (either 
implicit or explicit) within the TSPA-LA model, consistent with guidance provided in 
Appendix C of the Scientific Processes and Guidelines Manual (BSC 2002 [160313]). 
Table 9 describes the FEP that is included in the TSPA-LA through the use of the results of the 
analysis described in this document. Details of the implementation of this FEP are summarized 
in Section 6.5. The implementation of that included FEP in TSPA-LA is described in this 
analysis report. Details of the implementation are summarized here in the table, including 
specific reference to sections within this document. The parameters that address the included 
FEP are also listed. The sources of input for these parameters are described in Section 4 for 
input parameters and elsewhere in Section 6 if they were specifically developed within this 
document. Consequently, the supporting data, the alternative conceptual models considered by 
the PVHA, the findings and results, and the uncertainties documented in the PVHA as they relate 
to the listed FEP are considered to be implicitly included in the TSPA-LA (see Section 6.3.1). 

ANL-MGR-GS-000001 REV 01 26 September 2003 
Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
Table 9. Included Feature, Event, and Process for This Scientific Analysis Report and Its Disposition in Total System Performance Assessment for 
the License Application 
TSPA-SR FEP 
Number, Name, 
and Description 
TSPA-LA FEP 
Number, Name 
and Description 
Section Where 
Disposition Is 
Described 
Summary of TSPA-LA Disposition 
1.2.04.03.00 
Igneous Intrusion 
into Repository 
Magma from an 
igneous intrusion 
flows into the 
drifts and extends 
over a large 
portion of the 
repository site, 
forming a sill. The 
sill could be 
limited to the drifts 
or a continuous 
sill could form 
along the plane of 
the repository, 
bridging between 
adjacent drifts. 
1.2.04.03.0A 
Igneous Intrusion 
into Repository 
Magma from an 
igneous intrusion 
flows into the 
drifts and extends 
over a large 
portion of the 
repository site, 
forming a sill, 
dike, or dike 
swarm depending 
on the stress 
conditions. This 
could involve 
multiple drifts. 
The sill could be 
limited to the drifts 
or a continuous 
sill could form 
along the plane of 
the repository, 
bridging between 
adjacent drifts. 
Section 6.5 The technical basis for the inclusion of this FEP is provided in this analysis report by documenting 
the probability of a basaltic dike intersecting the repository footprint, the number of eruptive 
centers (conduits) within the repository footprint, and the length and azimuth of intersecting dikes 
within the repository footprint  each of these aspects is related to defining the consequence of 
an igneous intrusion into the repository. 
Parameters developed in this document that are a direct output to the Number of Waste 
Packages Hit by Igneous Intrusion scientific analysis report, Number of Waste Packages Hit by 
Igneous Intrusion (BSC 2003 [161851]), and implicitly included in the TSPA-LA include the 
following: 
  Conditional joint probability distribution for length and azimuth (within the repository) of an 
intersecting dike 
  Conditional joint probability distribution of the number of eruptive centers within the 
repository 
  Conditional marginal distributions for length of intersecting dike and number of eruptive 
centers within the repository footprint. 
The results of the probability analysis are used in the analyses of the number of waste package 
hit during an igneous intrusion and affected by conduit formation. The cumulative probability 
density function (CDF) of the number of waste packages hit is then used by the TSPA-LA model 
to determine the amount of waste released via an eruptive event and to determine the number of 
waste packages affected and the volume of waste subject to release via the groundwater 
pathway. Because the CDF for the number of waste packages hit is dependent on the underlying 
inputs, the underlying inputs and related FEPs are considered to be included implicitly in the 
TSPA-LA model. 
Parameters developed in this document that are direct outputs to and explicitly included in the 
TSPA-LA include the following: 
  Probability distribution for annual frequency of intersection of repository footprint by a dike 
  Summary frequencies of disruptive volcanic events. 
The TSPA-LA uses the probability distributions directly to weight the igneous contribution to 
annual dose. The results of this analysis report address this FEP by providing the basis for 
determining the mean probabilities used to weight igneous groundwater and eruptive dose. The 
values developed in this report represent full distributions, which are then binned together to 
generate a CDF of less than 100 points for the primary and contingency block values. 

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6.2 VOLCANIC HISTORY OF THE YUCCA MOUNTAIN REGION 
Because several Quaternary basaltic volcanoes exist within 20 km of the proposed Yucca 
Mountain repository (Figure 3), volcanism must be assessed as a possible future disruptive event 
in TSPA. Two major types of volcanism have occurred in the YMR: an early phase of Miocene 
silicic volcanism, the recurrence of which is considered unlikely and not of regulatory concern, 
and a more recent phase of Miocene and post-Miocene basaltic volcanism that is of regulatory 
concern (Reamer 1999 [119693], p. 5). 
DTNs: LAFP831811AQ97.001 [144279]; MO0003YMP98126.001 [149605] (both are used for reference only). 
Source: Numbers by each volcano indicate approximate age in millions of years (CRWMS M&O 1998 [105347], 
Chapter 2, Tables 2.B and 2.C; DTN: LAFP831811AQ97.001). 
NOTE: TM =Thirsty Mesa; PCF = Pliocene Crater Flat; BM = Buckboard Mesa; QCF = Quaternary Crater Flat; 
(MC = Makani Cone; BC = Black Cone; RC = Red Cone; LC = Little Cones); HC = Hidden Cone; 
LBP = Little Black Peak; LW = Lathrop Wells. 
Figure 3. Location and Age of Post-Miocene (< 5.3 million years (m.y).) Volcanoes (or Clusters Where 
Multiple Volcanoes Have Indistinguishable Ages) in the Yucca Mountain Repository 

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The earliest volcanism in the YMR was dominated by a major episode of caldera- forming, silicic 
volcanism that occurred primarily between ~15 and 11 m.y., forming the southwestern Nevada 
volcanic field (Sawyer et al. 1994 [100075]). Silicic volcanism was approximately coincident 
with a major period of extension, which occurred primarily between 13 and 9 m.y. (Sawyer 
et al. 1994 [100075], Figure 4). Yucca Mountain is an uplifted, erosional remnant of voluminous 
ash- flow tuff deposits formed during the early phase of silicic volcanism. 
The commencement of basaltic volcanism occurred during the latter part of the caldera-forming 
phase, as extension rates waned, and small-volume basaltic volcanism has continued into the 
Quaternary. In terms of eruption volume, the 15-m.y. history of volcanism in the YMR is 
viewed as a magmatic system that peaked between 13 and 11 m.y., with the eruption of over 
5000 km3 of ash flow tuffs, and has been in decline since, with relatively minor volumes of 
basalt erupted since 11 m.y. ago (CRWMS M&O 1998 [100129], Figure 3.9-2). Approximately 
99.9 percent of the volume of the southwestern Nevada volcanic field erupted by about 7.5 m.y. 
ago with the eruption of tuffs from the Stonewall Mountain volcanic center, which is the last 
active caldera system of the southwestern Nevada volcanic field. The last 0.1 percent of eruptive 
volume of the volcanic field consists entirely of basalt erupted since 7.5 m.y. ago (CRWMS 
M&O 1998 [100129], Figure 3.9-5). Based on eruption volume, the southwestern Nevada 
volcanic field is considered to have virtually ceased eruptive activity since about 7.5 m.y. 
Considered in terms of total eruption volume, frequency of eruptions, and duration of volcanism, 
basaltic volcanic activity in the YMR defines one of the least active basaltic volcanic fields in the 
western United States (e.g., CRWMS M&O 1998 [105347], Chapter 4, Figure 4-2, for 
post-Miocene basalts of Crater Flat). 
Post-caldera basalts in the YMR can be divided into two episodes: Miocene (eruptions between 
~9 and 7.3 m.y.) and post-Miocene (eruptions between ~4.8 and 0.08 m.y.). The time interval of 
about 2.5 m.y. between these episodes is the longest eruptive hiatus of basalt in the YMR during 
the last 9 m.y. (CRWMS M&O 1998 [105347], Chapter 3, Table 3.1). This eruptive hiatus also 
marks a distinct shift in the locus of post-caldera basaltic volcanism in the YMR to the southwest 
(CRWMS M&O 1998 [100129], Figure 3.9-6). The Miocene basalts and post-Miocene basalts 
are, thus, both temporally and spatially distinct. This observation emphasizes the importance of 
considering the age and location of the post-Miocene basalts (~ the past 5 m.y. of the volcanic 
history of the YMR) when calculating the volcanic hazard to the proposed Yucca Mountain 
repository. The PVHA experts almost exclusively considered the time period of interest to be 
pos-5 m.y. (with significant weight given to the post-1 m.y. period) as the time period of interest 
in assessing volcanic hazard at Yucca Mountain (CRWMS M&O 1996 [100116], Figure 3-62). 
The post-Miocene basalts formed during at least six episodes of volcanism (based on age 
groupings) that occurred within 50 km of the proposed Yucca Mountain repository (Figure 3). 
These six episodes, in order of decreasing age, consist of the (1) basalt of Thirsty Mesa, 
(2) Pliocene Crater Flat and Amargosa Valley, (3) Buckboard Mesa, (4) Quaternary Crater Flat, 
(5) Hidden Cone and Little Black Peak (the Sleeping Butte centers), and (6) Lathrop Wells. 
Three basalt episodes are in or near the Crater Flat topographic basin, within 20 km of Yucca 
Mountain. Several aeromagnetic anomalies in the Amargosa Valley have characteristics that 
indicate buried basaltic volcanic centers (Langenheim et al 1993 [148622], p. 1840). One of 
these anomalies (Anomaly B of Langenheim et al. 1993 [148622]) was drilled and basalt cuttings 

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dated at 3.85 m.y. using the 40Ar/39Ar method (CRWMS M&O 1998 [105347], Chapter 2, 
Table 2.B). Because of the similarity in age to the 3.75 m.y. Pliocene Crater Flat episode, the 
buried basalts of Amargosa Valley are considered here as part of the same episode. 
The total eruption volume of the post-Miocene basalts is about 6 km3. The volume of individual 
episodes has decreased progressively through time, with the three Pliocene episodes having 
volumes of approximately 1 to 3 km3 each and the three Quaternary episodes having a total 
volume of only ~0.5 km3 (CRWMS M&O 1998 [100129], Figure 3.9-2; Table 3). All of the 
Quaternary volcanoes are similar in that they are of small volume (~0.1 km3 or less, Table 10) 
and typically consist of a single main scoria cone surrounded by a small field of aa basalt flows, 
which commonly extend ~ 1 km from the scoria cone. 
The seven or eight (if Little Cones is counted as two volcanoes) Quaternary volcanoes in the 
YMR occur to the south, west, and northwest of Yucca Mountain in a roughly linear zone 
defined as the Crater Flat Volcanic Zone (Crowe and Perry 1990 [100973], p. 328). Five of 
seven Quaternary volcanoes are in or near Crater Flat and lie within 20 km of the Yucca 
Mountain site (Figure 3). Models that attempt to relate volcanism and structural features in the 
YMR have emphasized the Crater Flat basin because of the frequency of volcanic activity 
associated with Crater Flat and its proximity to the proposed Yucca Mountain repository 
(e.g Smith et al. 1990 [101019], p. 84; Connor and Hill 1995 [102646], p. 10122). 
Table 10. Estimated Volume and 40Ar/39Ar Agea of Quaternary Volcanoes in the Yucca Mountain 
Repository 
Volcano Volume (km3)b Volume (km3)c Age (m.y.)e 
Makani Cone 0.006 1.16-1.17 
Black Cone 0.105 0.07 0.94-1.10 
Red Cone 0.105 0.92-1.08 
Little Cones 0.002 >0.01d 0.77-1.02 
Hidden Cone 0.03 0.32-0.56 
Little Black Peak 0.03 0.36-0.39 
Lathrop Wells Cone 0.14 0.074-0.084 
DTNS: LA0004FP831811.002 [149593]; LAFP831811AQ97.001 [144279] (BOTH ARE USED FOR REFERENCE ONLY). 
NOTES a 40Ar/39Ar dates provide the most complete and self-consistent chronology data set for Quaternary 
volcanoes of the YMR. A full discussion of other chronology methods used to date basaltic rocks in the 
YMR can be found in CRWMS M&O (1998 [105347], Chapter 2). Other chronology methods may not 
provide consistent or accurate estimates of the time of eruption. 
b CRWMS M&O (1998 [105347], Chapter 3, Table 3.1), (DTN: LA0004FP831811.002 [149593]). 
c Stamatakos et al. (1997 [138819], p. 327). 
d Accounts for volume of buried flows detected by ground magnetic surveys. 
e Range of ages from CRWMS M&O (1998 [105347], Chapter 2, Table 2.B). Lathrop Wells ages (Heizler 
et al. 1999 [107255], Table 3) represent the range of plateau ages measured, except for sample 
LW157, a statistical outlier (DTN: LAFP831811AQ97.001 [144279]). 

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6.3 THE PROBABILISTIC VOLCANIC HAZARD ANALYSIS 
In 1995 to 1996, the DOE sponsored the PVHA project to assess the probability of a future 
volcanic event intersecting the proposed repository at Yucca Mountain. To ensure that a wide 
range of approaches was considered for the PVHA, the DOE identified 10 experts in the field to 
participate in the project and evaluate the data. Their evaluations (elicitations) were then 
combined to produce an integrated assessment of the volcanic hazard that reflects a range of 
alternative scientific interpretations. This assessment, which focused on the volcanic hazard at 
the site expressed as the probability of intersection of the proposed repository by a basaltic dike, 
provided input to an assessment of volcanic risk. 
6.3.1 The Probabilistic Volcanic Hazard Analysis Process 
The major procedural steps in the PVHA were selecting the expert panel members, identifying 
the technical issues, eliciting the experts judgments, applying temporal and spatial aspects of 
probability models, and compiling and presenting the results. 
6.3.1.1 Selecting the Expert Panel Members 
From more than 70 nominees, 10 individua ls were selected to participate in the PVHA project. 
Efforts were made to balance the panel with respect to technical expertise (geology, 
geochemistry, and geophysics) and institutional/organizational affiliation. The 10 experts and 
their affiliations are listed in Table 11 (CRWMS M&O 1996 [100116], Table 1-2). 
Table 11. Probabilistic Volcanic Hazard Analysis Panel Members 
Expert Abbreviation Affiliation 
Dr. Richard W. Carlson RC Carnegie Institute of Washington 
Dr. Bruce M. Crowe BC Los Alamos National Laboratory 
Dr. Wendell A. Duffield WD United States Geological Survey, Flagstaff 
Dr. Richard V. Fisher RF University of California, Santa Barbara (Emeritus) 
Dr. William R. Hackett WH WRH Associates, Salt Lake City 
Dr. Mel A. Kuntz MK United States Geological Survey, Denver 
Dr. Alexander R. McBirney AM University of Oregon (Emeritus) 
Dr. Michael F. Sheridan MS State University of New York, Buffalo 
Dr. George A. Thompson GT Stanford University 
Dr. George P. L. Walker GW University of Hawaii, Honolulu 
DTN: MO0002PVHA0082.000 
6.3.1.2 Identifying Technical Issues 
The PVHA panel of experts convened between February and December 1995. A technical 
facilitator/integrator led carefully structured, intensive interactions among the panel members. 
The experts participated in workshops, field trips, and other interactions, which were used to 
identify sources of agreement and disagreement among them. Each expert played the role of an 
informed technical evaluator of data, rather than a proponent of a particular interpretation. On 
occasion, however, some experts were asked to present particular interpretations to facilitate 
discussion and consideration of alternative interpretations. In all the interactions, it was made 

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clear that the purpose of the PVHA was to identify and understand uncertainty, not to eliminate 
it. It was also emphasized that the purpose was not necessarily to achieve consensus. Instead, 
disagreement was expected and accepted. 
At the core of the PVHA project were four workshops. The primary objective of the workshops 
was to ensure the experts understanding of the issues, alternative volcanic hazard models, and 
the data available on which they would base their technical assessments. The first three 
workshops focused on the data, volcanic hazard models, and interpretations relevant to the 
PVHA. The workshops included presentations of data and interpretations by technical 
specialists from the Los Alamos National Laboratory, the USGS, the University of Nevada, 
Las Vegas, and the Center for Nuclear Waste Regulatory Analysis, as well as from some PVHA 
experts. During the fourth workshop, the experts reviewed the preliminary assessments 
developed by the panel members, after which the individual elicitations were revised, based on 
feedback received. Two field trips held during the course of the PVHA provided the opportunity 
for the panel members to observe geologic relationships pertaining to eruptive style, the 
definition of volcanic events, and the distribution and timing of volcanic activity in the YMR. 
6.3.1.3 Temporal and Spatial Aspects of Probability Models 
Before the third PVHA workshop, an interactive meeting was held for the benefit of the expert 
panel, in order to focus on the methods available to calculate volcanic hazard. The methods were 
used to calculate the two main aspects of volcanic hazard probability models: the temporal and 
spatial aspects. 
Temporal models describe the frequency of occurrence of volcanic activity and include 
homogeneous and nonhomogeneous models. Many of the experts used homogeneous Poisson 
models to define the temporal occurrence of volcanic events, which assumes a uniform rate of 
volcanism based on the number of volcanic events that occurred during various periods in the 
past. Nonhomogeneous models were used by some experts to consider the possibility that 
volcanic events are clustered in time or to describe the possible waning or waxing of volcanic 
activity in the region during the period of time the experts believed was relevant to hazard 
analysis. 
Spatial models describe the spatial distribution (location) of future volcanic activity. The most 
common PVHA models considered the future occurrence of volcanoes to be homogeneous 
within particular defined regions or source zones (CRWMS M&O 1996 [100116], 
Figure 3-62). Source zones were defined based on several criteria: the spatial distribution of 
observed basaltic volcanoes (especially post-5 m.y. volcanoes), structurally-controlled regions, 
regions defined based on geochemical affinities, tectonic provinces, and other criteria. 
Nonhomogeneous parametric spatial distributions of future volcano occurrences were also 
modeled, for example, that the location of future volcanoes will follow a bivariate Gaussian 
distribution based on the location of volcanoes in Crater Flat. Finally, nonhomogeneous, 
nonparametric spatial density models were used by some experts to assess the spatial distribution 
of future volcanoes. These models make use of a kernel density function and smoothing 
parameter based on locations of existing centers to obtain the spatial distribution for location of 
future volcanoes. 

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6.3.1.4 Eliciting the Experts Judgments 
Formal elicitation followed the third workshop. The process consisted of a two-day individual 
interview with each expert. To provide consistency, the same interview team was used for all 
elicitations. Following the elicitation interview, each expert was provided with a written 
summary of his elicitation, which was prepared by the interview team. The expert reviewed and 
clarified the summary and had the opportunity to revise any assessments. To promote a full 
understanding of each individuals judgment, the preliminary assessments made by each member 
of the expert panel were presented and discussed at the fourth workshop. Following this 
workshop, each expert had a final opportunity to revise his assessments before the results of the 
PVHA were finalized (CRWMS M&O 1996 [100116], Appendix E). A summary of input 
parameters for the PVHA probability models is found in CRWMS M&O (1998 [106102], 
Table 10-5). 
6.3.1.5 Probabilistic Volcanic Hazard Analysis Results and Uncertainty 
The product of the PVHA was a quantitative assessment of the probability of a volcanic event 
intersecting the proposed repository and the uncertainty associated with the assessment 
(CRWMS M&O 1996 [100116], Figure 4-32). Specifically, a probability distribution of the 
annual frequency of intersection of a basaltic dike with the proposed repository footprint was 
defined. The contributions to uncertainty from each of the PVHA components is described in 
Probabilistic Volcanic Hazard Analysis for Yucca Mountain, Nevada (CRWMS M&O 1996 
[100116], Section 4.2). 
Each of the 10 experts independently arrived at a probability distribution for the annual 
frequency of intersection of the proposed repository footprint by a dike that typically spanned 
~2 orders of magnitude (CRWMS M&O 1996 [100116], Figure 4-31). From these individual 
probability distributions, an aggregate probability distribution for the annual frequency of 
intersection of the proposed repository footprint by a dike was computed that reflected the 
uncertainty across the entire expert panel (CRWMS M&O 1996 [100116], Figure 4-32). The 
individual experts distributions were combined using equal weights to obtain the aggregate 
probability distribution. The mean value of the aggregate probability distribution was 1.510-8 
dike intersections per year, with a 90 percent confidence interval of 5.410-10 to 4.910-8 
(CRWMS M&O 1996 [100116], p. 4-10). Note that these values are updated in this report for 
the proposed LA repository footprint in Section 6.5.3. The composite distribution spanned about 
three orders of magnitude for intersection frequency. The range in the mean frequencies of 
intersection for the individual experts interpretations spanned about one order of magnitude 
(CRWMS M&O 1996 [100116], Figure 4-32). The variance for frequency of intersection 
defined by the composite distribution was disaggregated to identify the contributions from each 
of the sources of uncertainty, including variability between the experts interpretations (CRWMS 
M&O 1996 [100116], Figure 4-33). Most of the uncertainty in characterizing the hazard arose 
from uncertainty in an individual experts interpretations of the hazard rather than differences in 
scientific interpretation between the experts (CRWMS M&O 1996 [100116], p. 4-10, 
Figure 4-33). The probability distribution arrived at by the PVHA accounted for undetected 
events (buried volcanic events, or intrusive events that never reached the surface). The 
undetected event frequency ranged from 1 to 5 times that of observed events, with most 
estimates in the range of 1.1 to 1.5 (CRWMS M&O 1996 [100116], Figure 3-62). 

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The PVHA results indicated that the statistical uncertainty in estimating the event rate was the 
largest component of intra-expert uncertainty (CRWMS M&O 1996 [100116], Figure 4-33). 
The next largest uncertainty was uncertainty in the appropriate spatial model. Other important 
spatial uncertainties included the spatial smoothing distance, Gaussian field parameters, zonation 
models, and event lengths. The temporal issues of importance included the time period of 
interest, event counts at a particular center, and the frequency of hidden events (CRWMS 
M&O 1996 [100116], Figure 4-33). 
6.3.1.6 Consideration of Alternative Conceptual Models 
The PVHA was in essence an exercise in combining multiple alternative conceptual models 
(ACMs) into a single distribution that captured the uncertainty in the experts conceptua l models 
of the physical behavior of volcanism in the YMR. ACMs incorporated into the results of the 
PVHA consisted primarily of alternative temporal and spatial models that describe expected 
behavior (based on past behavior) of volcanism in the YMR. No single base-case conceptual 
model is appropriate in the area of volcanism because the underlying physical processes that 
control the precise timing and location of volcanic events within a particular region remain 
largely unknown to science. 
Although numerous ACMs were incorporated in the PVHA, several alternative models not 
considered in the PVHA have emerged since the PVHA was completed in 1996. These models 
are summarized in Table 12 and are discussed in detail in Section 6 of this report. 
6.3.1.7 Significance of Buried Volcanic Centers on Probabilistic Volcanic Hazard 
Analysis Results 
The uncertainty in the event rate accounted for about 40 percent of the total intra-expert 
uncertainty (CRWMS M&O 1996 [100116], Figure 4-33). The event rate depends on the 
number of events estimated for a particular time period and for a particular source zone, and can 
be expressed as events/year/square kilometer (CRWMS M&O 1996 [100116], p. 3-2; Figure 17a 
of this report). A key parameter for estimating event rates is, therefore, an estimate of the 
number of volcanic events that have occurred in the YMR, particularly since the Miocene. Since 
all post-Miocene volcanic centers observable at the surface in the YMR have been identified 
(Figure 3), the only factor that could significantly change PVHA estimates of event counts and 
the event rate would be evidence not considered by the PVHA of a significant number of 
previously unidentified buried volcanic centers or intrusions. 

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Table 12. Alternative Conceptual Models Not Considered in the Probabilistic Volcanic Hazard Analysis 
Alternative Models Key Assumptions Assessment 
Anomalous strain rate in 
the YMR (Wernicke et al. 
1998 [103485]) 
Anomalously high current strain rate 
based on GPS measurements 
indicates volcanic event rate may be 
underestimated by factor of 10. 
Not considered plausible based on later 
measurements from Savage et al. (1999 
[118952]) that show low strain rate as well 
as questionable assumptions about links 
between strain rate and volcanic event rate. 
Mantle hotspot beneath the 
YMR (Smith et al. 2002 
[158735]) 
Anomalously high mantle basalt 
source temperatures lead to 
underestimation of future volcanic 
event rate. 
Not considered plausible based on weight of 
documented scientific opinion showing that 
mantle hotspot is not present beneath YMR. 
Tectonically weighted 
probability models (Connor 
et al. 2000 [149935], 
p. 427) 
Weighting of certain tectonic 
elements in probability models lead 
to probability estimates as high as 
10-7. 
Not considered plausible based on 
observation that tectonically weighted 
probability models are poor predictors of 
location of volcanism in YMR. 
Significant number of 
buried or undetected 
volcanic centers in the 
YMR (Hill and Stamatakos 
2002 [159500]) 
Aeromagnetic anomalies suggest 
that significant number of volcanic 
events were unaccounted for in the 
PVHA, underestimating the volcanic 
hazard. 
Significance of buried volcanoes on 
probability estimates cannot be assessed 
without further data collection and update of 
the PVHA. Sensitivity studies documented 
in Section 6.5.4 of this report are for 
information purposes only. The results of 
the 1996 PVHA, as summarized in Section 
7.2 of this report, are the results that will be 
used in TSPA-LA. 
Langenheim et al. (1993 [148622]) presented data for aeromagnetic anomalies in the Amargosa 
Valley and interpreted them as shallowly buried basaltic volcanic centers. These data were 
available to the PVHA experts (CRWMS M&O 1996 [100116], p. B-4), and data and 
interpretations concerning the Amargosa Valley anomalies were also presented by Langenheim 
during Workshop 1 of the PVHA project (CRWMS M&O 1996 [100116], p. C-3). In the 
PVHA, 9 of 10 experts included volcanic events of the Amargosa Valley in their YMR event 
counts (CRWMS M&O 1996 [100116], Appendix E, pp. RC-8, BC-17, WD-5, WH-7, MK-10, 
AM-8, MS-8, GT-6, GW-6). The only expert who did not include events of the Amargosa 
Valley in their YMR event counts considered only the past 2 m.y. to be the relevant time period 
(CRWMS M&O 1996 [100116], Appendix E, RF-6), thus, excluding the period of time during 
which the anomalies were probably formed. The most common expert assessment of the number 
of volcanic events represented by the aeromagnetic anomalies in Amargosa Valley was 5, with 
slightly less weight assigned to 3, 4, and 6 events (CRWMS M&O 1996 [100116], Figure 3-63). 
In addition, the PVHA experts assessed a hidden event factor, allowing for additional undetected 
events not counted in the total YMR event counts that already included the Amargosa Valley 
event counts (CRWMS M&O 1996 [100116], Figure 3-62, 3-63). These factors typically 
resulted in an increase of 10 to 50 percent in the rate of volcanic events over that computed from 
the observed volcanic events. 
New data that could potentially change the assessment of the number of volcanic events by the 
PHVA experts include an analysis of existing aeromagnetic data for the YMR (Earthfield 
Technology 1995 [147778]) and new ground magnetic surveys of aeromagnetic anomalies 
(Connor et al. 1997 [135969]; Magsino et al. 1998 [147781]). A map presented by Earthfield 
Technology (1995 [147778], Appendix II) indicates the presence of as many as 40 to 
60 aeromagnetic anomalies within ~35 to 40 km of Yucca Mountain that are interpreted as 

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intrusive bodies; six of these lie within ~5 km of the proposed repository site. The Earthfield 
Technology (1995 [147778]) results were based on the merging of three aeromagnetic data sets: 
the Timber Mountain, Lathrop Wells, and Yucca Mountain surveys. Subsequent to release of the 
Earthfield Technology (1995 [147778]) report, it was discovered that the report was flawed by 
an incomplete and mislocated Timber Mt. Survey (Feighner and Majer 1996 [105078], p. 1). 
Inspection of the flight survey map in Earthfield Technology (1995 [147778], Figure 2) and a 
corresponding map enclosed in Results of the Analysis of the Timber Mt., Lathrop Wells, and 
Yucca Mt. Aeromagnetic Data (Feighner and Majer (1996 [105078], Appendix I) indicates that 
the Timber Mountain Survey, which encompasses about 50 percent of the coverage area and the 
majority of the aeromagnetic anomalies, was mislocated approximately 20 km to the 
south-southwest of its correct location. For this reason, further analysis of the anomalies as 
presented by Earthfield Technology (1995 [147778], Appendix II), and that lie within the Timber 
Mountain survey, is not warranted. The six anomalies located within 5 km of the proposed 
repository site (the Yucca Mountain survey) are associated with mapped faults and are probably 
due to magnetic variation resulting from fault-controlled juxtaposition of rock masses with 
differing magnetic properties (Feighner and Majer 1996 [105078], p. 2; Reamer 1999 [119693], 
p. 32). 
The most reliable and detailed data available for magnetic anomalies in the YMR is presented in 
Connor et al. (1997 [135969]) and Magsino et al. (1998 [147781]). These data were obtained 
using ground magnetic surveys of 14 selected aeromagnetic anomalies located to the north, east, 
west, and south of the proposed repository site (Magsino et al. 1998 [147781], Figure 1-1). 
Collectively, these surveys represent a comprehensive assessment of aeromagnetic anomalies 
nearest the proposed repository site and provide confidence that the geologic record of basaltic 
volcanism near Yucca Mountain is adequately understood. Of the 14 surveys, seven provide no 
evidence of buried basalt and three were conducted over areas with known surface exposures of 
basalt, partly to enhance understanding of the relationship between volcanism and geologic 
structure (Magsino et al. 1998 [147781], Section 4). Four of the 14 surveys provide evidence of 
buried volcanic centers. Two of these (Anomalies A and F/G of the PVHA) were known to the 
PVHA experts as possible buried basaltic volcanic centers (from the data of 
Langenheim et al. 1993 [148622]; Crowe et al. 1995 [100110], Figure 2.5), but the data 
presented in Connor et al. (1997 [135969]) and Magsino et al. (1998 [147781]) provide increased 
detail and confidence of their volcanic origin. Of the two remaining surveys, anomalies in the 
Steves Pass area on the southwest margin of Crater Flat are interpreted as buried basalt. 
Interpretation of a buried, reversely magnetized body of rock southwest of Northern (or Makani) 
Cone is less certain and may be either a basalt body or Miocene tuff (Magsino et al. 1998 
[147781], Sections 4.4 and 4.11). Each of the four anomalies representing probable buried 
volcanic centers occur within volcanic source zones previously specified by the PVHA experts 
(CRWMS M&O 1996 [100116], Appendix E), except for the anomalies in the Steves Pass area, 
which lie slightly to the southwest of most experts volcanic source zones, in a direction away 
from Yucca Mountain. 
On the basis of evidence for buried volcanic centers presented in Connor et al. (1997 [135969]), 
Brocoum (1997 [147772]) conducted sensitivity analyses to assess the potential impact on the 
PVHA results of increased event counts in Amargosa Valley and Crater Flat. Considering the 
experts method for assessment of event counts, particularly for northeast alignments of vents (as 
in the case of Amargosa anomaly F/G), the mean value for the number of buried volcanic centers 

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was increased from the original PVHA value of 4.7 events to 6.1 events (Brocoum 1997 
[147772], Enclosure 1, p. 5). The mean annual frequency of intersection of a dike with the 
proposed repository footprint was recalculated using the revised event count distributions, 
resulting in an increase in the mean annual frequency of intersection of 4 percent (Brocoum 1997 
[147772], Enclosure 1, p. 5). Given the uncertainty factored into the PVHA by assessment of 
alternative event counts and hidden event factors, small changes in the PVHA event counts have 
a minor impact on the annual frequency of intersection distribution derived from the PVHA. 
A later sensitivity analysis presented by Synthesis of Volcanism Studies for the Yucca Mountain 
Site Characterization Project (CRWMS M&O 1998 [105347], Chapter 6, pp. 6-83 and 6-84) 
conservatively assumed that all known aeromagnetic anomalies in Crater Flat and the Amargosa 
Valley were Quaternary age, instead of Pliocene. Using this assumption, the most likely number 
of Quaternary volcanic events near Yucca Mountain based on PVHA event counts was increased 
from 3.8 to 8 events. This increase in the Quaternary event count resulted in a disruption 
probability of ~2.510-8 per year (CRWMS M&O 1998 [105347], Chapter 6, p. 6-84), a result not 
significantly different from the mean PVHA result of 1.510-8 per year (CRWMS M&O 1996 
[100116], pp. 4-10, 4-14). 
The data presented by Connor et al. (1997 [135969]) and Magsino et al. (1998 [147781]) provide 
stronger evidence that Anomalies A and F/G (as defined in the PHVA) represent buried volcanic 
centers, and that at least one anomaly not considered by the PVHA experts represents a probable 
buried volcanic center. Sensitivity studies (Brocoum 1997 [147772]; CRWMS M&O 1998 
[105347], Chapter 6) show that the addition of several volcanic events located within already 
defined volcanic source zones does not significantly impact the results of the PVHA. 
Significantly, the four anomalies east of Yucca Mountain (Magsino et al. 1998 [147781], 
Figure 1-1) show no evidence of buried volcanic centers and provide confirmatory evidence that 
the volcanic source zones specified by the experts to the south and west of Yucca Mountain are a 
valid representation of the spatial distribution of post-Miocene volcanism in the YMR. 
In 1999, the USGS conducted a regional aeromagnetic survey for the purpose of assessing 
potential hydrologic pathways in the Yucca Mountain/Death Valley region (Blakely et al 2000 
[151881]). Subsequent interpretation of these data indicated that 20 to 24 aeromagnetic 
anomalies present to the west and south of Yucca Mountain could potentially represent buried 
basalt (OLeary et al. 2002 [158468]; Hill and Stamatakos 2002 [159500]). Section 6.5.4 of this 
report documents an assessment of how the potential presence of additional buried volcanoes in 
the YMR could impact the frequency of intersection. 
6.3.1.8 Alternative Estimates of the Intersection Probability 
Several alternative estimates of the intersection probability (the annual probability of a volcanic 
event intersecting the proposed repository footprint) were presented between 1982 and 1998 
(Table 13). As discussed in the following section (6.3.2), volcanic events in hazard calculations 
have been represented as both points and lines (Table 13). For point events, volcanic source 
zone areas or the proposed repository area have generally been increased to account for the fact 
that volcanic events have dimension due to the length of associated dikes. The shorter the event 
length, the more comparable intersection probability results are for calculations representing 
volcanic events as either points or lines. Intersections probabilities near 10-7 intersections/year 

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ANL-MGR-GS-000001 REV 01 37 Septemb er 2003 
(Ho and Smith 1998 [140152], pp. 507 and 508; Reamer 1999, p. 61 [119693]) reflect unusually 
small volcanic source zone areas or unusually long event lengths (Table 13). 
Most of the published intersection probabilities, including the mean intersection probability 
estimated in the PVHA, cluster at values slightly greater than 10-8 per year (Table 13), indicating 
that this probability estimate is fairly robust, given the range of alternative temporal and spatial 
models, and event geometries considered in probability calculations. 
Table 13. Published Estimates of the Probability of Intersection of the Proposed Repository at Yucca 
Mountain by a Volcanic Event 
Reference 
Intersection 
Probability (per year) Comment 
Event 
Representation 
Crowe et al. (1982 [102741]), 
pp. 184 through 185 
3.3 10-10 - 4.7 10-8 Range of alternative probability 
calculations. 
point 
Crowe et al. (1993 [100026]), 
p. 188 
2.6 10-8 Median value of probability 
distribution. 
point 
Connor and Hill (1995 
[102646]), p. 10121 
15 10-8 Range of 3 alternative models. point 
Crowe et al. (1995 [100110]), 
Table 7.22 
1.8 10-8 Median value of 22 alternative 
probability models. 
point 
Ho and Smith (1998 
[140152]), pp. 507 through 
508 
(1) 1.5 10-8, 
(2) 1.09 10-8,   
2.83 10-8, 
(3) 3.14 10-7 
3 alternative models; 3rd model 
assumes a spatial intersection ratio 
(using a Bayesian prior) of 8/75 or 
0.11, approximately one order of 
magnitude higher than other 
publis hed estimates, because 
volcanic events are forced to occur 
within a small zone enclosing Yucca 
Mountain. 
point 
CRWMS M&O (1998 
[105347]), Chapter 6, p. 6-84 
2.5 10-8 Sensitivity analysis that 
conservatively assumes all 
aeromagnetic anomalies in 
Amargosa Valley are Quaternary 
age. 
point 
Connor et al. (2000 [149935]), 
p. 427 
10-8-10-7 Value of 10-7 assumes maximum 
event length of 20 km, regional 
recurrence rates of 5 events/m.y., 
and that crustal density variations 
contribute to event location. 
line 
6.3.2 Definitions and Parameters of a Volcanic Event and Implications for Alternative 
Probability Calculations 
An important issue in the PVHA and in alternative volcanic hazard assessments of the proposed 
Yucca Mountain repository is the definition of a volcanic event. The definition of a volcanic 
event can affect the outcome of probability calculations and must be clearly understood to 
compare the results of alternative probability calculations meaningfully. The PVHA experts 
defined a volcanic event to be a spatially and temporally distinct batch of magma ascending from 
the mantle through the crust as a dike or system of dikes (CRWMS M&O 1996 [100116], 
Appendix E). The physical manifestations of a volcanic event include the dike or dike system, 
and any surface eruption deposits. For the purposes of probability models discussed in this 

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report (Section 6.5), a volcanic event is defined as a point (x,y) in space representing the 
expected midpoint of the dike system involved in the magma ascent. The dike sys tem associated 
with the volcanic event is represented in probability model by a line element defined in terms of 
a length, azimuth and location relative to the point event (Figures 10 and 12). The term dike 
length used in the PVHA and in this report whe n discussing volcanic events refers to the total 
length of the dike system associated with the volcanic event. The phrase intersection of the 
repository footprint by a dike refers to intersection of the emplacement area of the repository by 
the line element representing the dike system associated with the volcanic event. The possibility 
that a dike system (e.g., multiple dikes) has width or consists of multiple parallel dikes does not 
significantly affect the intersection probability and is not part of the calculations in this report. 
The width of the dikes and the number of parallel dikes does affect the consequences of an 
intersection and is incorporated into the igneous intrusion scenario presented in Number of Waste 
Packages Hit by Igneous Intrusion (BSC 2003 [161851]). Although the PVHA assumed 
volcanic events to have both an extrusive and intrusive component (volcano and dike), the output 
of the PVHA was the annual frequency of intersection of the proposed repository by an intrusive 
basaltic dike (CRWMS M&O 1996 [100116], Section 4.2, Figure 4-32). The PVHA did not 
calculate the conditional probability that a dike intersecting the proposed repository would result 
in an extrusive volcanic eruption through the repository. 
Typical dike dimensions assigned by the experts were a dike width of one meter and a dike 
length (the total length of the dike system associated with a volcanic event) of 1 to 5 km 
(CRWMS M&O 1996 [100116], Appendix E; Figure 4). The most likely values for maximum 
dike lengths were estimated to be in the range of 17 to 22 km (CRWMS M&O 1996 [100116], 
Figure 3-62). The values of maximum dike length represent tails of distributions that have a 
small impact on the probability of dike intersection. The individual PVHA expert dike length 
distributions can be aggregated to derive a PHVA aggregate dike length distribution. The 
aggregate dike-length distribution derived from the PVHA has 5th-percentile, mean, and 
95th-percentile values of 0.6, 4.0, and 10.1 km, respectively (Figure 4). The most commonly 
assigned dike orientation centers around N30oE (CRWMS M&O 1996 [100116], Figure 3-62). 
Prior to the PVHA, most assessments of volcanic hazard to the proposed repository represented 
volcanic events as points having no physical dimension (CRWMS M&O 1996 [100116], 
p. 3-16). The physical dimension of events was generally taken into account by appropriately 
expanding the area of the proposed repository or of volcanic source zones (e.g., Crowe 
et al. 1995 [100110], p. 7-64). The PVHA and probability calculations presented by the 
U.S. Nuclear Regulatory Commission (NRC) since the PVHA have represented volcanic events 
as having both length and orientation (Reamer 1999 [119693]). It is important to compare the 
different representations of volcanic events in order to compare probability results meaningfully. 
The PVHA intersection probability represents the probability of a dike intersecting the repository 
footprint (CRWMS M&O 1996 [100116], Section 3.1.6). The NRC intersection probability 
represents the intersection of the repository footprint by a vent or vent alignment (Reamer 1999 
[119693], Sections 4.1.6.3.2 and 4.1.6.3.3, Figures 29 and 30), and assumes that all vents along 
the alignment are contemporaneous and represent a single volcanic event (e.g., the alignment of 
Quaternary vents from Makani Cone to Little Cones [Figure 3]). In contrast, the PVHA allowed 
that an alignment of volcanoes could represent one to several volcanic events that are not 
necessarily contemporaneous. Conceptually, use of either the PVHA or NRC volcanic event 
should result in the same intersection probability, if the same temporal/spatial models and 

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ANL-MGR-GS-000001 REV 01 39 Septemb er 2003 
assumptions are used, as well as the same probability distributions for event length and 
orientation (Figure 5). Howeve r, these probabilities represent different physical occurrences, and 
PVHA and NRC model parameters are not equivalent. Since the PVHA intersection probability 
represents the probability of a dike intersection, the probability of an eruption (conditional on 
dike intersection) through the proposed repository is equal to or lower than the intersection 
probability (Figure 5). The NRC intersection probability values are based on the interpretation 
that every intersection of a vent alignment with the proposed repository footprint results in an 
eruption through the proposed repository (Reamer 1999 [119693], p. 57), and that the probability 
of intersection by shallow intrusive events that do not erupt is necessarily higher, possibly by a 
factor of 2-5 (Reamer 1999 [119693], p. 60, Figure 5). 
Output Data. DTN: LA0009FP831811.001 [164712] 
NOTE: The 5th-percentile, mean, and 95th-percentile values are 0.6, 4.0, and 10.1, km, respectively. The 
distribution contains a very long upper tail extending to 86 km. The irregular shape of the probability mass 
function in the lower plot reflects the variation in the distributions defined by the individual experts. 
Figure 4. Composite Distribution for Dike Length Averaged Across All 10 Probabilistic Volcanic Hazard 
Analysis Experts 

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The NRC assumes that every vent alignment intersection will result in an eruption through the 
proposed repository because they conclude that vent spacings along alignments are small 
compared to the proposed repository footprint (Reamer 1999 [119693], Sections 4.1.4.3.3 and 
4.1.6.3.2). The technical basis for this conclusion is unclear. In Section 6.5.1.3, a number of 
alternative approaches for the number and spatial distribution of vents along the dike associated 
with a volcanic event are formulated, based on PVHA expert output and observed vent spacing 
in the YMR, to test for sensitivity of model choice. Using these approaches, the eruption 
probability is approximately 78 percent of the dike intersection probability, because of cases 
where no vents form within the repository footprint (Table 19). 
N/A - For Illustration Purposes Only 
Source:Reamer 1999 [119693] 
Figure 5. Conceptual Diagram Comparing Event Definitions from the Probabilistic Volcanic Hazard 
Analysis and Reamer: Implications for Eruption and Intrusion Probabilities Based on Different 
Event Definitions 
6.3.2.1 Intrusive Versus Extrusive Events: Evidence from Analog Sites 
Another issue requiring discussion is whether dikes or dike systems can reach the near surface 
without any portion of the system erupting. The NRC (Reamer 1999 [119693]) assumption that 
all vent alignment intersections result in eruption through the proposed repository implies that 
intrusive events that intersect the proposed repository and do not erupt represent entirely separate 
temporal events. Using the San Rafael volcanic field as an analog, the NRC assumes for PA 
purposes that the probability of separate intrusive events that do not erupt is 2 to 5 times higher 
than the probability of eruptive events (Reamer 1999 [119693], Section 4.1.6.4). Thus, for 
example, if 5 volcanic events resulting in volcanic eruptions have occurred in the YMR in the 
past 1 m.y., the NRCs assumption requires that 10 to 25 additional intrusive events have also 
occurred, independent in time and location from the events that produced the volcanic eruptions. 
In the PVHA definition of a volcanic event, intrusive and extrusive events, in the YMR are 
generally considered to be linked on a one-to-one basisa volcanic event is defined as an 
extrusive volcano and its associated intrusive dike or dike system. Dikes that reach depths of 
< 0.5 to 1 km are thought to erupt at some point along the length of the dike, mainly because of 
volatile exsolution (CRWMS M&O 1996 [100116], Appendix E, pp. RC-10, BC-6, WH-6, 
MK-12). The most common multiplier assigned for undetected intrusive events was 1.1 to 
lower probability higher probability annual probability 
intrusion 
probability 
eruption 
probability 
PVHA dike intersection 
probability 
NRC vent alignment 
intersection probability ??

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ANL-MGR-GS-000001 REV 01 41 Septemb er 2003 
1.2 times that of known volcanic events (CRWMS M&O 1996 [100116], Figure 3-62), which is 
a number lower than the NRC multiplier of 2 to 5. 
An appropriate analog in the YMR for understanding the relationship between intrusive and 
extrusive components of a volcanic event is the Paiute Ridge intrusive/extrusive center (Byers 
and Barnes 1967 [101859]) on the northeastern margin of the Nevada Test Site. Paiute Ridge is 
a small-volume Miocene volcanic center comparable in volume and composition to Quaternary 
volcanoes near Yucca Mountain (CRWMS M&O 1998 [105347], Chapter 5, p. 5-29). 
Paleomagnetic, geochronologic, and geochemical data indicate that the entire intrusive/extrusive 
complex formed during a brief magmatic pulse and, thus, represent a single volcanic event 
(Ratcliff et al. 1994 [106634]; CRWMS M&O 1998 [105347], Chapter 5, p. 5-29). The vents 
and associated dike system formed within an NNW-trending extensional graben provide 
excellent exposures of a variety of depths of the system including remnants of surface lava flows, 
volcanic conduits, and dikes and sills intruded into tuff country rock at depths of up to 
300 meters (CRWMS M&O 1998 [105347], Chapter 5, pp. 5-27 through 5-41). There is 
evidence of shallow structural control of dike emplacement at Paiute Ridge, including dike 
emplacement along fault planes (Byers and Barnes 1967 [101859]; CRWMS M&O 1998 
[105347], Chapter 5, pp. 5-27 through 5-28). Dike lengths at Paiute Ridge range from < 1 to 
5 km (CRWMS M&O 1998 [105347], Chapter 5, p. 5-31), comparable to the range estimated for 
post-Miocene volcanism near Yucca Mountain (Figure 4). 
Field observations at Paiute Ridge clearly show that, while some portions of individual dikes 
stagnated within about 100 meters of the surface without erupting, other portions of the same 
volcanic event did erupt, as evidenced by associated lava flows and volcanic conduits (Byers and 
Barnes 1967 [101859]; CRWMS M&O 1998 [105347], Chapter 5, pp. 5-29 through 5-33). 
During the time period considered most significant by the PVHA experts for evaluating volcanic 
hazard (the past 5 m.y., CRWMS M&O 1996 [100116], Figure 3-62), there is no known episode 
of dike intrusion to within a few hundreds meters of the surface in the YMR that has not been 
accompanied by an extrusive component. Thus, there is no evidence in the YMR geologic 
record to suggest that dike intrusions without accompanying eruptions occur 2 to 5 times more 
frequently than eruptions (Reamer 1999 [119693], Figure 5, Sections 4.1.6.3.4 and 4.1.6.4). 
The NRC assumption of higher intrusion probabilities in the YMR is based on analogy to the San 
Rafael volcanic field on the western Colorado Plateau, where an extensive system of shallowly 
intruded dikes is well exposed (Delaney and Gartner 1997 [145370]). Delaney and 
Gartner (1997 [145370], p. 1180) estimate that 174 dikes are represented in the San Rafael dike 
swarm. Breccias are present along portions of 45 of these dikes, which are interpreted to 
represent the subsurface beneath eruptive centers (Delaney and Gartner 1997 [145370], pp. 1178 
and 1191). No attempt is made in Delaney and Gartner (1997 [145370]) to estimate the 
frequency of temporally discrete intrusive versus eruptive events. They suggest only that at least 
45 dikes show evidence of eruption along some segment of a dike; other parts of the same dike, 
or other parts of the same dike system, may have erupted, as is observed at Paiute Ridge. Given 
the Paiute Ridge analogy and the Delaney and Gartner (1997 [145370]) interpretation that the 
San Rafael swarm likely represents the subsurface beneath a large volcanic field active for about 
a million years (Delaney and Gartner 1997 [145370], pp. 1177, 1178, and 1179), it is likely that 
many individual intrusive/extrusive events are represented at San Rafael, with some portion of a 
dike system erupting during each event, and other portions of the same dike system not erupting. 

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Thus, while the data and discussion presented in Delaney and Gartner (1997 [145370]) have 
been used to argue that intrusive events without an eruptive component occur 2 to 5 times more 
frequently than intrusive events with an eruptive component, an alternative interpretation is that 
the intrusion/extrusion ratio is closer to 1. This alternative interpretation is more consistent with 
the geologic record of the YMR, as demonstrated at the Paiute Ridge analog site. 
6.3.2.2 Alternative Event Lengths 
The length of dikes or vent alignments (Reamer 1999 [119693], Figure 30) can significantly 
affect intersection probabilities, depending partly on how far areas of high-event frequency are 
from the proposed repository. When volcanic events primarily occur far from the proposed 
repository, they must have sufficient length to intersect the repository, and longer event lengths 
will result in higher intersection probabilities. When volcanic events occur more frequently 
nearer the proposed repository, volcanic events with shorter lengths are able to intersect the 
repository with higher frequency. 
As evaluated by experts in the PVHA, the mean dike length associated with a volcanic event in 
the YMR is 4 km, and 95 percent of dikes are shorter than 10.1 km (Figure 4). These values are 
consistent with observed volcanic features in the YMR. For instance, the maximum vent spacing 
in the YMR is 5.4 km between Black and Makani Cones, and volcanic vent alignments lengths 
are typically in the range of 2 to 5 km (e.g., Hidden Cone-Little Black Peak, Amargosa 
Aeromagnetic Anomaly A, Red Cone-Black Cone). The longest proposed vent alignment in the 
YMR, assuming it represents one volcanic event, is the Quaternary Crater Flat alignment with a 
length of about 11 km (Figure 3). Observed dikes, such as at Paiute Ridge, range in length from 
< 1 to 5 km. Dike and vent alignments of the 3.7 m.y. basalts in southeast Crater Flat (Figure 3) 
are no more than 4 km in length. 
Event lengths used in probability models by researchers from the University of Nevada, 
Las Vegas (e.g., Smith et al. 1990 [101019]) and the NRC (Reamer 1999 [119693], Figures 29 
and 30) are significantly longer than those assessed by the experts in the PVHA. For example, 
Smith et al. (1990 [101019], p. 81) based the dimensions of high-risk volcanic source zones, 
used as a spatial control on event distribution in probability models, on the length of volcanic 
vent alignments at analog sites. The analog site chosen to define the dimensions of the 
high-risk zone is the relatively large-volume Fortification Hill volcanic field near Lake Mead, 
200 km southeast of Yucca Mountain. In terms of volume, Smith et al. (1990 [101019], p. 85) 
acknowledge that this volcanic field is not analogous to Quaternary volcanism near Yucca 
Mountain. The vent alignment length defined at Fortification Hill is 25 km (Smith et al. 1990 
[101019], p. 85). Smith et al. (1990 [101019], p. 87) consider this length to be an upper bound, 
and it corresponds to the > 99th-percentile value of the PVHA event length distribution 
(Figure 4). 
Vent alignment lengths are used directly in NRC probability calculations (Reamer 1999 
[119693], Sections 4.1.6.3.2 and 4.1.6.3.3, Figures 29 and 30) and have a maximum half-length 
range of 5.2 to 10.2 km, corresponding to a total- length range of 10.4 to 20.4 km. These values 
are based on the half- length of the Quaternary Crater Flat vent alignment (5.6 km, the longest 
half- length observed in the YMR), and the observation that vent alignment half- lengths of 10 km 
or more occur in other volcanic fields (Reamer 1999 [119693], p. 40). It is notable that 

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~97 percent of the 174 dike lengths measured in the San Rafael volcanic field (discussed above), 
which the NRC uses as a YMR analog, have total lengths of < 5 km (Delaney and Gartner 1997 
[145370], Figure 4). The median of the length distribution at San Rafael is ~1.1 km, and the 
maximum dike length is 8 to 9 km (Delaney and Gartner 1997 [145370], Figure 4), a distribution 
not dissimilar to that used in the PVHA (Figure 4). 
A measure comparable to dike half- length, the distance from the end of the dike nearest the 
proposed repository to the point of origin of the volcanic event, can be derived from information 
elicited in the PVHA (Figure 6). This distribution has a 5th-percentile, mean, and 95th-percentile 
values of 0.2, 2, and 5.6 km, which, given the previous discussions of observed dike lengths, 
vent spacings, and maximum observed half-length vent alignment of 5.6 km, is in excellent 
agreement with observed volcanic event features in the YMR. Note that the range of maximum 
event length values (10 to 20 km) used in NRC probability models (Reamer 1999 [119693], 
Figures 29 and 30), are comparable to the maximum dike lengths assessed by the PVHA experts. 
However, the NRCs use of a uniform distribution for dike half- length results in a much greater 
weighting in NRC probability models for dike lengths that represent the > 95th-percentile values 
assessed by the 10 PVHA experts (Figure 4). The NRC intersection probability value of 10-7 per 
year, assumed for purposes of NRC PA (Reamer 1999 [119693], p. 61), depends on a maximum 
vent alignment length of 20 km (Reamer 1999 [119693], Figure 30). 
6.3.3 Conceptual Models of Volcanism and Formulation of Probability Models 
In the PVHA and alternative assessments of volcanic hazard to the proposed Yucca Mountain 
repository, the conceptual model of volcanismhow and where magmas form and what 
processes control the timing and location of magma ascent through the crust to form volcanoes 
has a fundamental impact on how probability models are formulated and the consequent results 
of probability models (e.g, Smith et al. 1990 [101019]; CRWMS M&O 1996 [100116]; 
Reamer 1999 [119693]). 
In general, the PVHA experts viewed the YMR as part of the same extensional tectonic and 
volcanic regime as the rest of the southern Great Basin portion of the Basin and Range province, 
but several members of the panel noted the possible additional influence on volcanism of the 
Walker-Lane structural zone (CRWMS M&O 1996 [100116], Appendix E, e.g., pp. WD-1 and 
WH-1). The smaller volumes of basalt erupted in the YMR since the Miocene reflects waning of 
both tectonism and magmatism in this part of the Basin and Range Province (CRWMS 
M&O 1996 [100116], Appendix E, e.g., pp. RC-1, BC-3, WD-2, RF-3, WH-1, MK-1, AM-3). 

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Output data. DTN: LA0009FP831811.001 [164712] 
NOTE: This distribution is obtained by convolving the distributions for dike length with those for the location of the 
point event relative to the dike. The 5th-percentile, mean, and 95th-percentile values are 0.2, 2.0, and 5.6, 
km, respectively. The distribution contains a very long upper tail extending to 86 km. 
Figure 6. Composite Distribution for the Distance from the Point Volcanic Event to the End of the Dike 
Averaged Across All 10 PVHA Experts 
Some PVHA experts distinguished between deep (mantle source) and shallow (upper crustal 
structure and stress field) processes when considering different scales (regional and local) of 
spatial control on volcanism (CRWMS M&O 1996 [100116], Appendix E, e.g., pp. MK-2 and 
AM-1). The PVHA experts generally view volcanism in the YMR as a regional-scale 
phenomenon because of melting processes in the upper lithospheric mantle that produce small 
volumes of alkali basalt, which is a basalt type generated by relatively small percentages of 
mantle melting compared to other basalt types (CRWMS M&O 1998 [105347], Chapter 4, 
p. 4-4). The exact mechanism of mantle melting in the YMR is poorly understood but may be 
controlled by a complex combination of processes including the effect of residual heat in the 
lithospheric mantle from previous episodes of volcanism and the presence of a plate subduction 
system, local variations in volatile (water) content, variations in mantle mineralogy and 
chemistry, and the effect of regional lithospheric extension (CRWMS M&O 1996 [100116], 
Appendix E). Researchers who have analyzed magmatic processes in the YMR generally agree 
that the magnitude of mantle melting has drastically decreased since the middle Miocene and that 
all melts in the past few million years have been generated within relatively cool (compared to 
asthenospheric mantle) ancient lithospheric mantle, which is a factor that may contribute to the 

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relatively small and decreasing volume of basaltic melt erupted in the YMR since the Miocene 
(Farmer et al. 1989 [105284]; Yogodzinski and Smith 1995 [136262]; CRWMS M&O 1996 
[100116], Appendix E; Reamer 1999 [119693], pp. 17 and 47). 
An alternative to the hypothesis of melting within lithospheric mantle was presented by 
Smith et al. (2002 [158735]), who hypothesized instead that basaltic melts beneath the YMR are 
generated within hot upwelling asthenospheric mantle (mantle hotspot model). This model 
raises the possibility that the recurrence rate of basaltic volcanism near Yucca Mountain (the 
Crater Flat volcanic field) could increase in the next few thousand years to a level comparable to 
the more active Lunar Crater volcanic field, 100 miles to the north. This hypothesis is based on a 
proposed correlation between the timing of volcanic episodes between the Lunar Crater and 
Crater Flat fields, and a proposal that anomalously hot mantle underlies the region beneath both 
volcanic fields, providing a common mechanism that controls the timing of volcanic activity. If 
this hypothesis were valid, probability models that estimate the probability of volcanic disruption 
of the repository might need to be revised to account for the possibility of higher recurrence rates 
in the future. 
The hypothesis that recurrence rates of volcanism could suddenly increase because of 
anomalously hot mantle beneath the Yucca Mountain area is inconsistent with the following 
observations: 
  The Crater Flat volcanic field is one of the least active volcanic fields in the western 
United States, while the Lunar Crater field is one of the most active fields within the 
Basin and Range interior. This fundamental difference in eruptive behavior does not 
suggest a common physical mechanism that links the two fields. Basaltic volcanic fields 
are common througho ut the western United States, with at least 20 to 30 fields active in 
the last 5 m.y. Many of these volcanic fields consist of 50 to 100 individual volcanoes, 
with several of the largest containing more than 300 individual volcanoes. Eruption 
rates for most fields range from 10 to more than 100 km3/m.y. (Perry and Bowker 1998 
[159502]). The Lunar Crater field consists of 70 to 100 individual volcanoes, with an 
eruption rate of approximately 20 km3/m.y. over the past 4 m.y. In contrast, the Crater 
Flat field consists of about 10 to 15 individual volcanoes, with an eruption rate of 
< 1 km3/m.y. over the past 4 m.y. (Perry and Bowker 1998 [159502]). These data 
indicate a recurrence rate in the Lunar Crater field that is approximately an order of 
magnitude greater than in the Crater Flat field. If, as proposed, the common link 
between the two fields is anomalously hot mantle, the lower volume, eruption rate, and 
recurrence rate of the Crater Flat field indicates that the underlying mantle is not as hot, 
or prone to melt, as mantle beneath Lunar Crater. Indeed, the low activity of the Crater 
Flat field compared to nearly every other volcanic field in the western U.S. indicates that 
the underlying mantle is not particularly hot. Therefore, there is no evidence to indicate 
that the recurrence rate of volcanism near Yucca Mountain will ever reach values 
equivalent to those at Lunar Crater. 
  Neodymium isotopic compositions of basalts in the Lunar Crater and Crater Flat 
volcanic fields are significantly different, indicating fundamentally different mantle 
sources or fundamental differences in processes that produced the basalts. 
Smith et al. (2002 [158735]) recognized the isotopic differences between the two 

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volcanic fields and speculated that the unusual Nd isotopic compositions of basalt near 
Yucca Mountain are due to (1) contamination of asthenospheric melts passing through 
lithospheric mantle or (2) modification of asthenospheric mantle by fluids or melts 
derived from subducted crust. Either mechanism would no t be expected to affect the 
basalts near Yucca Mountain selectively, but would instead operate on a much larger 
scale. For example, because subducted crust existed beneath most of the western United 
States for tens of millions of years, modifying fluids of melts derived from subducted 
crust would be expected to modify asthenospheric mantle on a continental scale, not just 
the small region surrounding Yucca Mountain. Basalts from Lunar Crater have isotopic 
compositions similar to ocean island basalts, indicating a source in relatively warm and 
convecting asthenospheric mantle. The unusual Nd isotopic composition of basalts in 
the Crater Flat field indicate derivation from a lithospheric mantle source that is old, 
stable, and cold (nonconvecting) compared to asthenospheric mantle (Perry et al. 1987 
[162311]; Farmer et al. 1989 [105284]; Livaccari and Perry 1993 [162310]). 
Wernicke et al. (1987 [107250]), citing tectonic evidence, suggested that the relative 
lack of volcanism in the YMR until 15 m.y. ago left the lithosphere cold and difficult to 
extend compared to more volcanically active and earlier extended regions of the Basin 
and Range province. The preponderance of evidence indicates that the small volume of 
basalt and limited volcanic activity near Yucca Mountain reflect an underlying mantle 
source that is cold and unable to produce significant volcanic activity. 
On a more local and shallow crustal scale, most researchers conclude that (1) volcanism is 
correlated with zones of past or present crustal extension, and (2) once dikes feeding volcanoes 
enter the shallow upper crust, their location and orientation is influenced by the orientation of the 
local stress field and the presence of faults that may locally control vent location and alignment. 
The evidence cited for these two conclusions includes several northeast-oriented vent alignments 
in the YMR and the association of eruptive centers with known or inferred faults 
(Smith et al. 1990 [101019], p. 83; CRWMS M&O 1996 [100116], Appendix E, e.g., p. AM-4; 
Connor et al. 1997 [135969], p. 78; Reamer 1999 [119693], Section 4.1.3.3.3; Fridrich 
et al. 1999 [107333], p. 211). 
A mechanistic model relating mantle melting and lithospheric extension has recently been 
proposed for the YMR by Connor et al. (2000 [149935]) and, additionally, is used as the 
geologic basis for weighting spatial density models based on crustal density variations across the 
YMR (Reamer 1999 [119693], Section 4.1.6.3.3). The conceptual basis of the model is that 
crustal density variations across the YMR control variations in lithostatic pressure at the base of 
the crust. These pressure variations, in turn, control the location of decompression melting 
within the mantle, which, in turn, controls the location of future igneous activity within the YMR 
(Connor et al. 2000 [149935], pp. 419 through 422). 
As formulated, a finite-element model that calculates lateral pressure changes in the YMR based 
on upper crustal density variations (Connor et al. 2000 [149935], p. 420) is a poor predictor of 
volcano distribution in the YMR. The model predicts that maximum melting (and, hence, more 
frequent occurrence of volcanism) will occur farthest from the region of high crustal density 
(Connor et al. 2000 [149935], Figure 3), but note that this model predicts the opposite of what is 
observed for the occurrence of post-Miocene volcanism in the YMR because volcanism is 

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concentrated near high-density crust of the Bare Mountain domain rather than farther to the east 
(Figure 7). 
Inspection of a map of apparent crustal density variation (Connor et al. 2000 [149935], Plate 1) 
shows that low average crustal density extends fairly uniformly for a distance of at least 50 km 
east of the Bare Mountain Fault. Within the context of the conceptual model proposed by 
Connor et al.,(2000 [149935] (i.e, crustal density exerts a primary control on location of 
volcanism), post-Miocene volcanism should occur somewhat randomly across this broad region. 
Instead, all post-Miocene volcanism near Yucca Mountain is located within 5 to 10 km of the 
Bare Mountain fault or near the southern ends of the Windy Wash and Stagecoach Road faults 
(Fridrich et al. 1999 [107333], p. 211), indicating that local zones of extension and upper crustal 
faulting may exert more direct control on the location of volcanism than the effect of shallow 
crustal processes on deep mantle processes (CRWMS M&O 1996 [100116], Appendix E, 
e.g., pp. AM-5 and MS-2; Fridrich et al. 1999 [107333], p. 211; Reamer 1999 [119693], 
Section 4.1.5.3.3). This is not to say that areas of low crustal density and volcanism do not often 
coincide, but instead that both are independently influenced or caused by upper crustal faulting 
and extension. 
Connor et al. (2000 [149935]) uses crustal density as a primary tectonic or geologic control 
on volcano distribution (Reamer 1999 [119693], Section 4.1.6.3.3), even though volcano 
distribution is not randomly distributed over broad areas of low crustal density as predicted by 
this model. An alternative method of weighting spatial density models would be to weight by 
estimated percent of extension within the Crater Flat basin (e.g., Fridrich et al. 1999 [107333], 
Figure 5), thereby tying probability models more directly to a geologic process (faulting and 
extension) that many researchers agree exerts an important geologic control on volcano location 
(Smith et al. 1990 [101019], p. 83; CRWMS M&O 1996 [100116], Appendix E, e.g., pp. AM-5 
and MS-2; Connor et al. 1997 [135969], p. 78; Reamer 1999 [119693], Section 4.1.3.3.3, p. 47). 
The strong southward and westward increase in extension rate across the Crater Flat basin 
corresponds well to sites of most recent volcanism in the basin (Fridrich et al. 1999 [107333], 
Figures 1 and 5), as opposed to crustal density variations that are hypothesized to control volcano 
location but do not correspond well with volcano location (Reamer 1999 [119693], Figure 22). 
In terms of alternative conceptual models, models based on observable geologic features in the 
YMR provide a more defensible framework and technical basis for probability calculations than 
models relying on unobservable processes that remain largely speculative (i.e., Reamer 1999 
[119693], Section 4.1.5.3.2; see also Probability Acceptance Criteria 3, Reamer 1999 [119693], 
p. 24). 
In summary, the probability model proposed by Connor et al. (2000 [149935]) that relies on 
spatial density functions weighted by crustal density is not well supported based on observations 
of volcano distribution within the YMR. Significantly, this probability model is the basis for 
calculating the highest annual probability value for a volcanic eruption within the proposed 
repository boundary (910-8 per year, Reamer 1999 [119693], Figure 30), which is the value 
(rounded up to 10-7 per year) that the NRC will use for the purposes of PA (Reamer 1999 
[119693], p. 61). It should also be noted that this probability model results in an approximately 
two- fold increase in the intersection probability compared to unweighted spatial density models 
(Reamer 1999 [119693], Figure 29). As discussed previously in Section 6.3.2.2, the results of 

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this probability model also depend to a large extent on dike lengths that are inconsistent with the 
geologic record of the YMR. 
6.4 THE CRATER FLAT STRUCTURAL DOMAIN 
Clearly, post-Miocene volcanoes in the YMR are spatially clustered (Crowe et al. 1995 
[100110], Chapter 3; Connor and Hill 1995 [102646], Figure 2). For probability models that 
incorporate clustering of volcanoes (Connor and Hill 1995 [102646]) or specify volcanic source 
zones based primarily on the location or clustering of volcano centers (CRWMS M&O 1996 
[100116]), estimation of the hazard to Yucca Mountain is often dominated by the presence of the 
Crater Flat cluster. This is due to the relatively high occurrence and Quaternary age of volcanoes 
in the Crater Flat basin (including Lathrop Wells, which lies within the Crater Flat structural 
domain and is the youngest volcano in the YMR), and because of the close proximity of Crater 
Flat volcanoes to Yucca Mountain, compared to other volcanic clusters in the YMR (Figure 3). 
The Crater Flat structural domain as defined by Fridrich (1999 [118942], pp. 170 through 178) is 
a structural basin or graben. It is bounded on the west by the Bare Mountain fault and on the east 
by structures buried beneath Jackass Flats (Figure 7). It includes the Crater Flat topographic 
basin on the west and Yucca Mountain near the center of the structural basin (Figure 7). Because 
the proposed Yucca Mountain repository lies within the Crater Flat structural basin, the structural 
and geophysical features of the basin, and to what degree they influence the location of 
volcanism within the basin, have been a key factor in conceptual models of volcanism that 
provide the geologic framework for assessing hazards to the proposed repository. 
The following sections describe the internal structure of the Crater Flat basin, as well as how the 
PVHA experts and subsequent investigators have interpreted the influence of structural 
characteristics of the basin in estimating the locations of future volcanic events. Based largely 
on work published since the PVHA, the evidence that the northeastern and southwestern portions 
of the basin have different extensional histories that may have influenced the location of basaltic 
volcanism within the basin is summarized below. 

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Source: Basalts of different ages are shown in relation to basin structure (modified from Fridrich et al. 1999 
[118942], Figure 1). The 70-ka age of the Lathrop Wells volcano indicated in the legend was estimated 
based on preliminary data subsequently published in Heizler et al. (1999) [107255], which indicates an 
age closer to 80 k.y. 
NOTE: PCF = Pliocene Crater Flat; MC = Makani Cone; BC = Black Cone; RC = Red Cone; LC = Little Cones; 
LW = Lathrop Wells. 
Figure 7. Local Structural Domains and Domain Boundaries of the Yucca Mountain Repository and 
Internal Structures of the Crater Flat Basin and Selected Parts of Adjacent Domains 

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6.4.1 Internal Structure and Boundaries of the Crater Flat Basin 
The Crater Flat structural domain (also referred to herein as the Crater Flat basin) comprises 
the Crater Flat topographic basin (west of Yucca Mountain), Yucca Mountain, and the western 
part of Jackass Flats. Based on geologic mapping and interpretation of subsurface structures 
from geophysical surveys (discussed below), the Crater Flat structural domain appears to 
comprise a single, westward-sloping, faulted basin (Figure 8). The western boundary of the 
Crater Flat basin coincides with the Bare Mountain fault and the northward extension of the fault 
into the Tram Ridge and Tates Wash faults (Fridrich 1999 [118942], p. 174). The Bare 
Mountain fault dips steeply (64  5 near the southern end) and can be imaged by seismic 
reflection to depths of at least 3.5 km and possibly to depths of 6 km (Brocher et al. 1998 
[100022], pp. 956 and 966). Logically, this major fault probably extends to the brittle-ductile 
transition in the middle crust. The northern boundary consists of a gradational termination of 
intrabasin structure at the perimeter of the Timber Mountain caldera complex (Fridrich 999 
[118942], p. 174). As defined by Fridrich (1999 [118942], pp. 174 and 176), the northeastern 
boundary coincides with Yucca Wash, which is an alluvium- filled valley inferred to be underlain 
by a small northwest-striking right- lateral strike slip fault or zone of faults (Fridrich 999 
[118942], pp. 174 and 176). The fault is nowhere exposed but is inferred from the fact that 
Yucca Wash is a linear valley separating Yucca Mountain from a domain to the northeast in 
which the 12.7- to 12.8-m.y. Paintbrush Group and older rocks are more extended than on 
northern Yucca Mountain (Fridrich 1999 [118942], p. 176). Day et al. (1998 [100027], p. 11) 
summarize evidence indicating that a major fault is not present beneath Yucca Wash. 
The eastern and southern margins of the domain are not physiographically distinct but, rather, 
merge with adjacent portions of the Basin and Range. The eastern margin of the Crater Flat 
basin is probably a buried, down-to-the-west fault known as the Gravity Fault (Fridrich 999 
[118942], p. 176, Figure 7). The southern margin is inferred from gravity and magnetic data, 
and from discontinuous outcrops, to be a fault structure buried beneath young alluvium. It is 
typically drawn in a northwestern direction along the Amargosa Valley (Fridrich 1999 [118942], 
p. 176). Fundamental changes in the style, timing, and magnitude of extension and other 
deformation occur across all of the boundaries of the Crater Flat basin. 

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Source: Modified from Brocher et al. 1998 [100022] 
NOTE: Location of cross section is indicated in Figure 7. 
Figure 8. Schematic Cross Section of the Crater Flat Basin, from Seismic, Reflection Surficial Geology, 
and Borehole Information 
6.4.1.1 Fault Orientations, Dip Directions, and Displacements 
In the center of the Crater Flat basin, a sequence of 12.7 to 12.8 m.y. ash-flow tuffs (primarily 
the Tiva Canyon and Topopah Spring Tuffs of the Paintbrush Group) crop out. These exposed 
tuff units comprise Yucca Mountain and adjacent mesas. Much of the information about 
orientation, offset, and timing of faulting is based on examination of faults that cut through the 
exposed tuffs. Because both Crater Flat and Jackass Flats are basins that have undergone 
alluviation in the late Quaternary, much of the structure of these basins is not accessible to direct 
observation. Information on structures beneath Crater Flat and Jackass Flats is derived mainly 
from seismic, gravity, and aeromagnetic and ground magnetic data. 
The Crater Flat basin is characterized by an array of closely spaced, small-to-moderate sized 
extensional faults that generally dip towards the center of the basin (Figure 8). Normal faults 
within the Crater Flat basin strike northerly in the northeastern part of the basin but change to 
increasingly northeasterly to the south and west across the basin (Figure 7). These orientations 
can be measured directly where faults are exposed on Yucca Mountain and can be inferred from 
the strike of aeromagnetic and gravity anomalies where buried beneath young basin fill. In 
general, the fault pattern within Crater Flat basin is roughly radial to the caldera complex to the 
north and curved from north to south across the basin. Based on the strike directions of faults 
within the Crater Flat basin, a northwest-trending hinge line can be defined 
(Fridrich et al. 1999 [107333], p. 208) that separates an area of predominantly north-striking 
faults on the northeast from an area of predominantly northeast-striking faults on the southwest 
(Figure 7). The hinge line marks the approximate location of (1) the 20 contour of clockwise 
rotation of the Tiva Canyon Tuff, (2) a subtle yet abrupt decline in elevation to the southwest, 
and (3) an increase in Quaternary displacement for faults southwest of the hinge line 
(Fridrich et al. 1999 [107333], p. 208; Stamatakos et al. 1997 [138819], p. 327). These 
observations are consistent with a division of the Crater Flat basin into two portions, separated at 

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the approximate position of the hinge line (Figure 7): (1) a northeastern, less extended portion, 
and (2) a southwestern, more extended portion (Fridrich et al. 1999 [107333], p. 208; 
Stamatakos et al. 1997 [138819], pp. 327 through 328). 
Seismic reflection surveys show that the Crater Flat basin is deepest to the west 
(Brocher et al. 1998 [100022], Figure 6; see also Ferrill et al. 1996 [105315], Figure 1b), 
implying that extension is also greatest to the west. Stratigraphic thickening of Miocene 
volcanic rocks to the west support this interpretation (Fridrich et al. 1999 [107333], p. 198). 
Thus, Crater Flat basin is a single, westward-dipping graben, with less fault displacement in the 
eastern half, within which no major faults dominate (Figure 8). 
Nearly all faults of the Crater Flat basin have at least a small component of oblique offset 
(Fridrich 1999 [118942], p. 177). Stratal tilts increase strongly to the west and south from an 
area of minimum tilts in the northeastern part of the basin on north Yucca Mountain. Faults in 
the southern part of the basin have a shallower dip and generally greater hanging wall tilt. In the 
northeastern part of the basin, cumulative extension is 7 to 15 percent. In contrast, cumulative 
extension in the southwestern part of the basin is at least 50 to 100 percent. This greater 
extension results from decreased spacing between the intrabasin faults and to increased average 
throw of the major faults (Fridrich et al. 1999 [107333], pp. 197 through198). 
6.4.1.2 Rotation of Faults 
The curved pattern of faults and the difference in orientation of faults from northeast to 
southwest in the Crater Flat basin is attributed to southward increasing clockwise vertical-axis 
rotation, whereby fault blocks together with their bounding faults were rotated from their original 
positions. On the scale of the basin as a whole, the spatial variation of declination 
(i.e., interpreted as vertical-axis rotation) is very smooth (Rosenbaum et al. 1991 [106708], 
pp. 1976 and 1977; Hudson et al. 1996 [106194]; Fridrich et al. 1999 [107333], Figure 8). The 
hinge line that is defined from the strike directions of faults corresponds approximately to the 
contour of 20o clockwise rotation of the Tiva Canyon Tuff. In general, more than 20o of 
clockwise rotation is present southwest of this line, and less than 20o of rotation is present 
northeast of the hinge line. In the northeastern part of the basin, cumulative clockwise rotation is 
generally < 5o; in contrast, cumulative rotation in the southwestern part of the basin is > 45o 
(Fridrich et al. 1999 [107333], p. 197). Paleomagnetic data from the Crater Flat basin are 
interpreted to show that older stratigraphic units are rotated more than younger units and that the 
major pulse of vertical-axis rotation followed the major episode of extension by about 1 m.y. 
The major pulse of rotation occurred between 11.6 and 11.45 m.y. (Hudson et al. 1996 [106194]; 
Fridrich et al. 1999 [107333], p. 210). The close association in the areal pattern of vertical axis 
rotation with the magnitude of extension in the Crater Flat basin suggests that the rotation and 
extension are related as a consequence of fan-like opening of the basin (Fridrich et al. 1999 
[107333], p. 210). 
6.4.1.3 Quaternary Slip Rate 
Based on the areal variation in the pattern of late Quaternary extension in the Crater Flat basin, a 
strong southward increase in deformation rate exists. Slip rates determined on individual faults 
generally increase to the south (Fridrich et al. 1999 [107333], pp. 197 and 208; Fridrich 1999 

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[118942], p. 177). In addition, cumulative late Quaternary (900 to 100 k.y.) extension measured 
along three profiles yields 0.025, 0.1, and 0.2 percent per m.y. from north to south across the 
basin (Fridrich et al. 1999 [107333], p. 207). Thus, the original fan- like pattern of basin opening 
established in the Miocene still persists. The continuing pattern of oblique basin opening 
indicates that vertical-axis rotation must still be occurring at a rate that is significant relative to 
the rate of extension (Fridrich et al. 1999 [107333], pp. 207 and 208). 
Wernicke et al. (1998 [103485], p. 2098) presented data from global positioning system surveys 
that they interpreted as indicating a strain rate near Yucca Mountain three to four times the Basin 
and Range average. Based on this conclusion, they suggested that the volcanic hazard at Yucca 
Mountain may have been underestimated by an order of magnitude (Wernicke et al. 1998 
[103485], p. 2099). A more recent study (Savage et al. 1999 [118952]) using data covering a 
longer time period than Wernicke et al. (1998 [103485]) interpreted the data to suggest that 
within the error of the measurements, the strain rate near Yucca Mountain measured between 
1983 to 1998 was not significantly different from zero (Savage et al. 1999 [118952], p. 17631). 
The suggestion that postulated anomalous strain rates near Yucca Mountain would lead to an 
order-of-magnitude increase in the volcano recurrence rate is not consistent with the 
post-Miocene volcanic record of the YMR. The total volume of basalt erupted during the past 
million years near Yucca Mountain is less than 0.5 km3, and is part of a systematic decline in the 
volume of basalt erupted over the past 5 m.y. (CRWMS M&O 1998 [105347], Chapter 4, 
p. 4-12). This million-year record of low-volume volcanism is inconsistent with the hypothesis 
that approximate 100,000 year time intervals within this period have involved particularly high 
strain rates that would lead to an order-of-magnitude increase in magmatic activity, as stated by 
Wernicke et al. (1998 [103485], p. 2099). Furthermore, the youngest episode of volcanism near 
Yucca Mountain occurred as a temporally isolated event ~80 k.y. ago at Lathrop Wells, with no 
volcanism occurring since (CRWMS M&O 1998 [105347], Chapter 2, Sections III and IV). 
This observation is inconsistent with the Wernicke et al. (1998 [103485], p. 2099) hypothesis 
that Lathrop Wells may represent the onset of a cluster of volcanic events that may continue for 
several tens of thousands of years. Savage et al. (1998 [145359], p. 1007b) calculated that an 
order-of-magnitude increase in the volcano recurrence rate would result in a 90 percent 
probability of a new volcano forming since 80 ka. No such event has occurred. 
Savage et al. (1998 [145359], Figure 1) also presented fault displacement data showing that 
deformation rates in the YMR have decreased since about 60 k.y. ago, suggesting that the region 
is not currently within a period of anomalous strain rate that would couple to increased volcano 
recurrence rate. 
6.4.1.4 Basin Subsidence and Fault Displacement 
A greater subsidence in the southwestern part of the Crater Flat basin can be inferred from a 
lower elevation and, therefore, a greater sedimentation rate compared to the northeastern part of 
the basin. A subtle topographic decline (lower on the southwest side) corresponds with the hinge 
line, defined from the strike directions of faults (discussed above), along most of its length. The 
lower elevation is a function of greater total amount of extension to the southwest of the hinge 
line. Most faults that cross the hinge line show a pronounced southward increase in both 
Quaternary displacement and total bedrock displacement across it (Fridrich et al. 1999 [107333], 
pp. 197 and 208; Fridrich 1999 [118942], p. 177), especially near the western margin (Bare 

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Mountain fault) and central part (southern Yucca Mountain) of the basin. Miocene and Pliocene 
sediments are only slightly offset at the northern end of the Bare Mountain fault, whereas 
Holocene sediments are significantly offset near the southern end of the fault 
(Stamatakos et al. 1997 [138819], p. 327). Also, growth of alluvial fans is greater along the 
southern part of the fault. Differences in fan growth are indicative of increased fault slip in the 
southwestern part of the basin and are compatible with measured slip rates along the Bare 
Mountain fault from 0.02 mm/yr in the north to 0.21 mm/yr along the southern part of the fault 
(Ferrill et al. 1996 [105315], p. 562). Along the eastern side of Crater Flat, cumulative offset on 
the Solitario Canyon fault is approximately 1000 m greater to the south compared to the north 
(Stamatakos et al. 1997 [138819], p. 327). Greater differential subsidence in the southwestern 
part of the Crater Flat basin is correlated with a greater thickness of Quaternary alluvium in this 
part of the basin compared to adjacent parts. For exa mple, lava flows associated with Little 
Cones are buried beneath approximately 15 meters of alluvium, whereas Red and Black Cones, 
of approximately the same age, are more completely exposed. 
To summarize, a variety of structural data, including fault orientations, direction of dip, total and 
late Quaternary extension, vertical-axis rotation, and basin subsidence, are interpreted to show 
that the northeastern part of the Crater Flat basin is significantly different from the southwestern 
part of the basin. That is, each part of the basin has a distinctive style of deformation; the two 
regions of the basin can be distinguished from each other across a well-defined though 
gradational boundary, the hinge line extending obliquely across the Crater Flat basin (Figure 7). 
Thus, the northeastern and southwestern parts of the Crater Flat basin comprise structurally 
distinct portions of the basin with the southwestern portion characterized by a history of greater 
extension. 
6.4.1.5 Correlation with Volcanism 
The post-Miocene basaltic centers of the Crater Flat basin lie within the southwestern part of the 
basin (Figure 7). This portion of the basin is coincident with the zone of greatest transtensional 
deformation, between the hinge line of the basin and the Bare Mountain fault, suggesting that 
this extensional zone controlled the ascent of basalt through the upper crust (Fridrich et al. 1999 
[107333], p. 210). The youngest volcano in the Crater Flat basin, the 80-ka Lathrop Wells 
volcano, lies between the southern ends of the Windy Wash and Stagecoach Road faults, the 
most active site of late Quaternary faulting in the Crater Flat basin (Fridrich et al. 1999 [107333], 
p. 211). Thus, there is a close spatial and temporal relationship between sites of extension and 
volcanism throughout the Crater Flat basin (Fridrich et al. 1999 [107333], p. 211). The 
restriction of three episodes of post-Miocene volcanism to the transtensional zone in the Crater 
Flat basin suggests that volcanism is less likely to occur at Yucca Mountain, which lies outside 
of the transtensional zone, in an area where no post-Miocene volcanism has occurred 
(Fridrich et al. 1999 [107333], p. 210, Figure 17a). As discussed in the next section, the PVHA 
experts recognized the close association between volcanism and areas of maximum extension in 
the YMR (CRWMS M&O 1996 [100116], pp. RC-5, BC-12, AM-5, MS-2, GT-2). Subsequent 
geologic and geophysical studies provide corroborative evidence that areas of maximum 
extension in the Crater Flat basin correspond closely to volcanic source zones defined in the 
PVHA (Stamatakos et al. 1997 [138819]; Brocher et al. 1998 [100022]; Fridrich et al. 1999 
[107333]). 

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6.4.2 Probabilistic Volcanic Hazard Analysis Volcanic Source Zones: Relationship to 
Crater Flat Structura l Features and the Probability of Dike Intersection 
The correlation between the structurally active portion of the Crater Flat basin and sites of 
volcanism within the basin indicate that Yucca Mountain is near, but not within, a local volcanic 
zone that may produce small volumes of future volcanism (CRWMS M&O 1996 [100116], 
Appendix E, expert zone maps). Although local source zones were chosen by PVHA experts 
based largely on the location of past volcanic events, they correspond to the areas of highest 
cumulative extension and most active faulting in the Crater Flat basin (Fridrich et al. 1999 
[107333], Figures 5 and 6), an association recognized by several of the PHVA experts (CRWMS 
M&O 1996 [100116], pp. RC-5, BC-12, AM-3 through 5, GT-2). In all cases in which local 
zones were defined, they were restricted to the southwestern portion of the Crater Flat basin or 
defined elongated, northwest-trending belts that included the southwestern portion and stretched 
to the Timber Mountain area (Figures 9a and 9b). All of the local zones excluded the 
northeastern portion of the Crater Flat basin, in which the proposed Yucca Mountain repository 
is located (Figures 9a and 9b). Based on structural arguments, therefore, and the past patterns of 
the close association of volcanism and extension, the eastern boundaries of local volcanic source 
zones defined in the PVHA separate more tectonically active and less tectonically active portions 
of the Crater Flat basin and may be reasonable predictors of the eastern extent of volcanism 
expected in the future. 
In terms of probability calculations, the volcanic source zones defined in the PVHA represent 
local regions of higher event frequency (southwestern Crater Flat), whereas northeastern Crater 
Flat (which includes Yucca Mountain) falls within a regional background source zone of lower 
event frequency (Figure 17a). According to the intersection probability models used in the 
PVHA, two mechanisms can generate a disruptive event at Yucca Mountain: either a volcanic 
event is generated within a local source zone (higher probability event) to the west of Yucca 
Mountain and has the appropriate location and dike characteristics (length and azimuth) to 
intersect the proposed repository, or a volcanic event is generated within a regio nal background 
zone (lower probability event) and intersects the repository. Because the probability of 
intersection of a volcanic event with the proposed repository includes components of both 
mechanisms, the intersection probability estimated for the repository should reflect spatial event 
frequencies that lie between local source zone values and regional background values, consistent 
with the results of the PVHA, and appropriate for a site that lies outside of a local volcanic 
source zone but near enough possibly to be affected by dikes generated within the source zone. 
In summary, many models of the experts related the areas of greatest likelihood for future 
volcanic activity to the region where previous volcanism has occurred and in which extensional 
deformation has been and continues to be greatest, i.e., to the southwestern portion of the Crater 
Flat basin (CRWMS M&O 1996 [100116], pp. RC-5, BC-12, AM-5, MS-2, GT-2, and expert 
zone maps; Figures 9a and b). Analysis by the NRC also indicates that the highest likelihood of 
future volcanic activity is in southwestern Crater Flat (Reamer 1999 [119693], Sections 4.1.5.4 
and 4.1.6.3.3; Figure 28). Given that the southern and southwestern portion of the Crater Flat 
basin is the most extended (Ferrill et al. 1996 [105315]; Stamatakos et al. 1997 [138819]; 
Fridrich et al. 1999 [107333]; Reamer 1999 [119693], p. 47) and that the locus of post-Miocene 
volcanism in the Crater Flat basin lies in the south and southwestern portion of the basin 
(Fridrich et al. 1999 [107333]; Reamer 1999 [119693], p. 47), volcanic source zones defined in 

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the PVHA and centered in southwestern Crater Flat are consistent with the tectonic history and 
structural features of the Crater Flat structural domain (Figures 9a and b, Figure 17a). 
DTN: MO0002PVHA0082.000 [148234] (for zone boundaries only ) 
Source: Superimposed on the Fridrich et al. (1999 [107333], Figure 1) map are boundaries of selected volcanic 
source zones (locally homogeneous spatial and temporal model, CRWMS M&O 1996 [100116], 
Section 3.13) defined by the PVHA experts that lie within the Crater Flat basin (CRWMS M&O 1996 
[100116], Appendix E). 
NOTE: MC = Makani Cone; BC = Black Cone; RC = Red Cone; LC = Little Cones; LW = Lathrop Wells. 
Figure 9a. Local Structural Domains and Domain Boundaries of the Yucca Mountain Repository and 
Internal Structures of the Crater Flat Basin and Selected Parts of Adjacent Domains 

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DTN: MO0002PVHA0082.000 [148234] (FOR ZONE BOUNDARIES ONLY) 
Source: Superimposed on the Fridrich et al. (1999 [107333], Figure 1) map are boundaries of selected volcanic 
source zones (locally homogeneous spatial and temporal model, CRWMS M&O 1996 [100116], 
Section 3.13) defined by the PVHA experts that lie within the Crater Flat basin (CRWMS M&O 1996 
[100116], Appendix E). 
NOTE: MC = Makani Cone; BC = Black Cone; RC = Red Cone; LC = Little Cones; LW = Lathrop Wells. 
Figure 9b. Local Structural Domains and Domain Boundaries of the Yucca Mountain Repository and 
Internal Structures of the Crater Flat Basin and Selected Parts of Adjacent Domains 

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6.5 RECALCULATION OF FREQUENCY OF INTERSECTION AND 
DEVELOPMENT OF DISTRIBUTIONS FOR LENGTH AND ORIENTATION OF 
DIKES AND FOR THE NUMBER OF ERUPTIVE CENTERS WITHIN THE 
PROPOSED REPOSITORY FOOTPRINT 
The PVHA (CRWMS M&O 1996 [100116]) presented a methodology for calculating the 
frequency of intersection of the proposed repository by a volcanic event and presented 
interpretations of 10 experts that were used to compute a distribution for the frequency of 
intersection that quantified the scientific uncertainty in the PVHA assessment. To evaluate the 
consequences of an intersection, information is needed on the length and orientation of the 
intersecting dike or dikes and the probability that an eruptive center (the vent above the conduit 
feeding an erupting volcano) forms within the emplacement area of the repository. This section 
of the report develops these assessments. In addition, the current configuration of the proposed 
LA repository emplacement area has a different outline from that used in the PVHA (CRWMS 
M&O 1996 [100116]). Consequently, the distribution for frequency of intersection was 
recalculated as part of this report, using the proposed repository footprint for the LA. 
In the context of the PVHA, a volcanic event is a spatially and temporally distinct batch of 
magma ascending from the mantle through the crust as a dike or system of dikes (CRWMS 
M&O 1996 [100116], Appendix E). For the purposes of the probability models discussed in this 
report, a volcanic event is defined as a point (x,y) in space representing the expected midpoint of 
the dike system involved in the magma ascent. The dike system associated with the volcanic 
event is represented in probability model by a line element defined in terms of a length, azimuth 
and location relative to the point event (Figures 10 and 12). The term dike length used in the 
PVHA and in this report when discussing volcanic events, refers to the total length of the dike 
system associated with the volcanic event. The phrase int ersection of the repository footprint by 
a dike refers to intersection of the emplacement area of the repository by the line element 
representing the dike system associated with the volcanic event. The possibility that a dike 
system (e.g., multiple dikes) has width or consists of multiple parallel dikes does not 
significantly affect the intersection probability and is not part of the calculations in this report. 
The width of the dikes and the number of parallel dikes does affect the consequences of an 
intersection and is included in Number of Waste Packages Hit by Igneous Intrusion (BSC 2003 
[161851]). 
The approach used to compute the frequency of intersection of the proposed repository by a 
volcanic event is illustrated in Figure 10. The PVHA experts specified spatial and temporal 
models that define the frequency of occurrence of volcanic events in the region around Yucca 
Mountain. A grid is constructed over this region with a spacing of 0.5 kilometer in the x 
(east-west) and y (north-south) directions (a 1-kilometer spacing was used in the original PVHA 
calculation, CRWMS M&O 1996 [100116]). At each location in the grid, x and y, the annual 
frequency of occurrence of volcanic events, l(x,y,t), is computed from the experts spatial and 
temporal models. The variable t indicates that this rate is defined to be the present day rate. The 
volcanic events occurring at point (x,y) will have an associated dike. The experts defined 
distributions for the length and orientation of the possible dike or dike system that may be 
associated with volcanic events. Shown schematically on Figure 10 are four possible alternative 
representations of the dike system associated with the volcanic event. Of these four, two are at 
the proper orientation and of sufficient length to intersect the proposed repository. Using the 

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distributions for dike length and orientation, the fraction of all the possible alternative dike 
systems associated with volcanic events at point (x,y) that intersect the proposed repository is 
computed. This is defined as the conditional probability of intersection for volcanic events at 
point (x,y), PI(x,y). The frequency of intersecting volcanic events at point (x,y) is then the 
frequency of volcanic events, l(x,y,t), multiplied by the conditional probability of intersection. 
The process is repeated for all locations in the grid, producing the frequency of intersection at 
each point. The sum of these values over all locations in the grid is the annual frequency of 
intersection of the proposed repository by volcanic events, the computed result of the PVHA. 
The PVHA analysis did not make any assessment of the consequences of an intersection of the 
proposed repository footprint by a dike. Consequently, a potential dike that extended all the way 
through the proposed repository, such as dike 2 on Figure 10, has the same contribution to the 
frequency of intersection as a shorter dike that only extends part way into the proposed 
repository, such as dike 4 on Figure 10. However, an assessment of consequences requires 
information on the length and orientation of the intersecting dikes within the proposed 
repository. Consequently, the PVHA calculation process was modified to provide this 
information. This is accomplished by a straightforward disaggregation of the intersection 
frequency into relative frequencies for discrete increments of length and azimuth. A series of 
bins with length increments of 0.05 kilometer and azimuth increments of 5 were set up. This 
discretization is sufficiently fine to provide an accurate picture of the distribution of lengths and 
azimuths of intersecting dikes. Then, when a volcanic event produces an intersection in the 
hazard calculation, the resulting length and azimuth within the proposed repository footprint are 
computed, and the event is assigned to the appropriate bin. At the end of the calculation, the 
value in each bin represents the frequency of intersections that produce the specific values of 
length and azimuth represented by the bin. The sum of the numbers in all of the length-azimuth 
bins equals the frequency of intersection. The values in each bin divided by the frequency of 
intersection provide a conditional distribution for length and azimuth given an intersection. This 
calculation is completely defined by the interpretations developed by the PVHA expert panel 
(CRWMS M&O 1996 [100116], Appendix E) and requires no additional assumptions. 

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N/A - For Illustration Purposes Only 
Figure 10. Schematic Illustrating Procedure for Computing the Frequency of Intersection of the 
Proposed Repository by a Volcanic Event 
The additional evaluation needed for consequence analyses is a conditional distribution for the 
number of eruptive centers that occur within the proposed repository footprint given that there is 
an intersection by a dike associated with a volcanic event. Evaluation of this distribution 
requires an assessment of the number of eruptive centers associated with a volcanic event and the 
spatial distribution for eruptive centers along the length of the dike. The PVHA experts were not 
asked to make these assessments as part of their characterization of the volcanic hazard. The 
PVHA experts did assess the number of volcanic events represented by the observed eruptive 
centers in the YMR. These assessments, together with the characteristics of Quaternary 
volcanoes in the YMR and a limited number of assumptions (described in Section 5), are used to 
derive empirical distributions for the number of eruptive centers per volcanic event (presented in 
Attachment III). Application of these assessments in the calculation of the number of eruptive 
centers within the proposed repository requires assessment of the possible correlation between 
number of eruptive centers and dike length and on the spatial distribution of eruptive centers 
along the length of the dike. Calculations are performed in this report using a range of possible 
assessments to incorporate these uncertainties into the analysis. 

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The assessments of the distributions for length and orientation of intersecting dikes developed in 
this report use the geometric representation of a dike employed in the PVHA (CRWMS 
M&O 1996 [100116]). As such, dikes are linear features having only length and orientation. 
The evaluation of the consequences of a dike intersection of the proposed repository footprint 
requires additional information on the width of the intersecting feature. Assessments of the 
width of intersecting dikes is presented in BSC (2003 [161838]). 
6.5.1 Formulation 
This section describes the mathematical formulation required to compute the conditional 
distributions for the length and azimuth of intersecting dikes within the proposed repository 
footprint and the number of eruptive centers within this footprint. The formulation is an 
extension of the mathematical fo rmulation used to compute the frequency of intersection of the 
proposed repository footprint by a dike in the PVHA (CRWMS M&O 1996 [100116], 
Section 3). 
6.5.1.1 Frequency of Intersection of the Proposed Repository Footprint by a Dike 
This section restates the PVHA formulation (CRWMS M&O 1996 [100116], Section 3) to 
introduce terms and notation. 
The PVHA study provided a distribution for the annual frequency of intersection of the proposed 
repository, n I(t), computed using the relationship (CRWMS M&O 1996 [100116], p. 3-2): 
n I (t) = l(x , y,t) PI( x, y)dxdy 
R 
 (Eq. 1) 
where l(x,y,t) is the rate of volcanic events at location (x,y) for the current time t; PI(x,y) is the 
conditional probability that a dike associated with the volcanic event at point (x,y) intersects the 
proposed repository boundary; and R is the region surrounding the proposed repository. Note 
that the notation for intersection has been changed from a subscript I in CRWMS M&O (1996 
[100116]) to a superscript I in this report for clarity. 
The actual calculation was performed on a 0.5-km  0.5-km grid spacing using the numerical 
summation: 
n I (t) = l(xi , yj , t) PI ( xi , yj ) 
j 
i 
DxDy (Eq. 2) 
The PVHA experts quantified the uncertainty in n I(t) by developing a set of alternative 
probability models and model parameters for all aspects of the hazard calculation. These were 
organized in the logic tree format shown in Figures 11a and 11b. 

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Source: Modified from CRWMS M&O 1996 [100116]. 
Figure 11a. Logic Tree Structure Used to Characterize Uncertainty in Volcanic Hazard 
Source: Modified from CRWMS M&O 1996 [100116]. 
NOTE: These subtrees are attached to the overall logic tree shown on Figure 11a. 
Figure 11b. Logic Tree Structure for Subtrees Addressing Uncertainty in Volcanic Hazard from Specific 
Sources 

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The end branches of these logic trees define a discrete joint distribution for the parameters, Q, 
required to perform the calculation. Thus, Equation 2 becomes: 
n I (t qS ) = l(xi , yj ,tqS ) PI ( xi , yj ,qS ) 
j 
i 
DxDy (Eq. 3) 
where qS is the parameter set associated with an individual end branch of one experts logic tree. 
The probability that n I(t|qS) is the correct frequency of intersection, given the experts 
characterization of the uncertainty in the process, is given by the probability that the parameter 
set Q takes on the specific values defined by qS, P(Q = qS). This discrete probability is obtained 
by multiplying all of the conditional probabilities at each node along the path through the logic 
tree that leads to qS. The mean or expected frequency of intersection is given by: 
E n I (t) [ ]= n I (t qS ) P(Q = qS ) 
s  
(Eq. 4) 
and the percentiles of the distribution for n I(t) are obtained by ordering the values of n.I(t|qS) and 
then summing the probabilities P(Q = qS) until the desired percentiles are reached. 
6.5.1.2 Conditional Distribution for Length and Azimuth of an Inters ecting Dike 
The above formulation for the PVHA hazard computation gives the overall frequency of 
intersection, n I(t). However, to compute the consequences of an intersection, one needs to know 
the distribution for length and orientation of the intersecting dikes. This distribution is 
developed by breaking down (disaggregating) the total frequency, n I(t|qS), into frequencies for 
specific values of intersecting dike length, LI
m, and dike azimuth, fn. The process involves 
computing the spatial disaggregation of the frequency of intersection into the contributions from 
each location (xi,yj) in the spatial grid around the proposed repository, n xi, y j 
I (tqS ) (see Figure 10). 
At each point (xi,yj), the conditional probability of intersection is the probability that dikes of all 
lengths and azimuths will intersect the proposed repository. The conditional probability of 
intersection is divided into probabilities for intersection from dikes with specific lengths and 
azimuths. As a result, the frequency of intersection from volcanic events at point (xi,yj) is 
divided into the frequency of intersection from volcanic events at point (xi,yj) that produce 
specific values of length, LI
m, and azimuth, fn, within the proposed repository footprint, 
n xi, y j 
I (t, Lm
I ,fn qS ). Summing these frequencies over all locations gives the frequency of 
intersection with a specific value of length and azimuth from all volcanic events, n I(t,LI
m,fn|qS). 
Dividing this frequency by the total frequency of intersection, n I(t|qS), gives the conditional 
probability that an intersecting dike will produce a specific value of length and azimuth within 
the proposed repository. 

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The conditional probability of intersection, PI(x,y,qS), in Equation 3 is computed using the 
relationship (CRWMS M&O 1996 [100116], p. 3-17): 
PI ( xi , yj ,qS ) = f(dqS ) 
0 
Lmax q S   f (f qS )df 
f1 x,y,d 
f 2 x, y, d    
  
  
 
dd (Eq. 5) 
where: 
f(d|qS) is the probability that a dike associated with a volcanic event at (x,y) will extend a 
distance d toward the proposed repository 
Lmax is the maximum length of a dike 
f(f|qS) is the density function for dike azimuth 
f1x,y,d and f2x,y,d define the range of azimuths over which a dike extending d from a 
volcanic event at (x,y) will intersect the footprint of the proposed repository. 
These parameters are illustrated in Figure 12. The integration over dike length in Equation 5 is 
also computed by summation. 
NA - For Illustration Purposes Only 
NOTE: Parameters are defined in text preceding this figure, except L is the length of the dike, LI and f are the 
length and azimuth, respectively for that portion of an intersecting dike within the proposed repository 
footprint, and LIm and fn are specific bins of intersection length and azimuth. 
Figure 12. Definition of Parameters Used to Compute the Probability of Intersection of the Proposed 
Repository Footprint by a Volcanic Event 

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The density function f(d|qS) is computed by convolving the distribution for the total length of the 
dike, f(L|qS), with a distribution for the normalized location of the dike relative to the volcanic 
event, f(EL|qS). Figure 13 illustrates the process using example distributions defined by one of 
the PVHA expert panel members. Part (a) of Figure 13 shows the probability distribution for the 
total length of the dike associated with a volcanic event, f(L|qS). Typically these were defined by 
the PVHA experts to be skewed distributions with long upper tails. Part (b) shows a distribution 
for the normalized location of the point event [point (x,y)] relative to the total length of the dike, 
f(EL|qS). These were defined as symmetric distributions over the range of 0 to 1, typically with 
higher probability for locations at the midpoint [the dike centered on point (x,y)] than at the ends 
[the dike extending for its full length in one direction away from point (x,y)]. Part (c) shows the 
resulting probability and cumulative probability distributions for distance from the proposed 
repository to the end of the dike (d = ELL) obtained by convolving the distributions from (a) 
and (b). 
NA - For Illustration Purposes Only 
Figure 13. Example Distributions for Dike Length, L, (part a); Normalized Location of the Point Volcanic 
Event Relative to the Total Length of the Dike, EL, (part b); and the Resulting Distribution for 
Distance from the Point Volcanic Event to the End of the Dike, d (part c) 

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Using these definitions, the summation form of Equation 5 becomes: 
PI ( xi , yj ,qS ) = P(Lp qS ) 
Lp = 0 
Lp =Lmax q S  P(Eo
L qS ) P(fn qS ) 
fn = f1 x, y, Eo
L  Lp 
f n =f2 x,y,Eo
L  Lp 
 
Eo
L =0 
Eo
L =1 
 (Eq. 6) 
where: 
P(Lp|qS) is a discrete probability mass function for dike length 
P(Eo
L qS ) is a discrete probability mass function for the relative location of the dike on the 
volcanic event 
P(fn|qS) is a discrete probability mass function for dike azimuth 
f1 x, y,Eo
L  Lp and f2 x, y,Eo
L  Lp again define the range of azimuths over which a dike 
extending d = Eo
L  Lp from a volcanic event at (x,y) will intersect the proposed repository 
footprint. 
The three probability mass functions are obtained by discretizing the continuous probability 
density functions developed for L, EL, and f by the PVHA experts. 
As the summation in Equation 6 is performed, it can be disaggregated into bins defined by 
azimuth increments, fn, and intersection length increments, LI
m, where LI is the length of 
penetration of a dike into the proposed repository (see Figure 12). As a result, Equation 6 can be 
rewritten as: 
PI ( xi , yj ,qS ) = PI (Lm
I ,fn xi ,y j ,qS ) 
n 
m  
(Eq. 7) 
The quantity PI(LI
m,fnxi,yj,qS) is the probability that a dike associated with a volcanic event at 
location (xi,yj) will intersect the proposed repository with length LI
m and azimuth fn, and is given 
by: 
PI (Lm
I ,fn xi ,yj ,qS ) = P(Lp qS ) 
Lp = 0 
Lp = Lmax qS  P(Eo
L qS )d (LI = Lm
I ) P(fn qS ) 
Eo
L = 0 
Eo
L =1 
 (Eq. 8) 
where d(LI = Lm
I ) = 1 for those combinations of Lp, L 
o E , and fn that result in LI = LI
m for a 
volcanic event at (x,y), and d(LI = Lm
I ) = 0 otherwise. 

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Multiplying Equation 8 by the frequency of volcanic events at (xi,yj) and summing over all 
locations yields the frequency of occurrence for intersections of the proposed repository of 
length LI
m and azimuth fn: 
n I (t,Lm
I , fn qS ) = l(xi , yj ,t qS ) PI (Lm
I ,fn xi , yj ,qS ) 
j 
i  
(Eq. 9) 
Because the summation of n I(t,LI
m,fn|qS) over the mn LI and f intervals equals n I(t|qS) 
nI (t qS ) = n I (t,Lm I
,fnqS ) 
n 
m 
  
    
  
   , the ratio n I(t,LI
m,fn|qS)/n I(t|qS) defines the relative frequency 
of intersection events with length LI
m and azimuth fn. 
Equation 9 can be recast into the form: 
n I (t,Lm
I , fn qS ) = l(xi ,y j , tqS )  PI ( xi ,y j ,qS ) [ ] 
j 
i 
 
PI (Lm I
,fn xi , yj ,qS ) 
PI ( xi , yj ,qS ) 
  
  
  
  
  
  
or, if we define : n x i ,y j 
I (t qS ) = l(xi ,yj ,tqS )  PI ( xi ,yj ,qS ) 
n I (t,Lm
I , fn qS ) = n xi , yj 
I (tqS ) [ ] 
j 
i 
 
PI (Lm
I ,fn xi , yj ,qS ) 
PI ( xi , yj ,qS ) 
  
  
  
  
  
  
(Eq. 10) 
The first term in brackets defines the contribution to the frequency of intersection from volcanic 
events occurring at point (x,y), n xi, y j 
I (tqS ). The second term in brackets defines the joint 
distribution for intersection length and azimuth from volcanic events at point (x,y) conditional on 
intersection occurring. 

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The only parameters of qS that affect the second term are the specification of the dike length, 
dike location on the volcanic event, and dike azimuth distributions. The PVHA experts specified 
these distributions to be independent of the distributions that characterized the spatial density and 
frequency of volcanic events. Thus Q can be broken into two independent sets: D Q and E Q . 
Parameters D Q are those that define the distributions for total length, location relative to the 
point volcanic event, and azimuth of the dike associated with the volcanic event [the parameters 
used in the computation of the conditional probability PI(x,y)]. These are defined by the first 
two levels of the logic tree shown on Figure 11a. Parameters E Q are those that define the 
distribution for volcanic event frequency, l(x,y,t). These are defined by all of the remaining 
levels of the logic trees shown on Figures 11a and 11b. Therefore, the expected or mean value of 
n I(t,LI
m,fn|qS) (Equation 4) can be written as: 
E n I (t,Lm I
,fn Q) [ ]= P(QD =qSD 
D ) 
PI (Lm I
,fn xi , yj ,qSD 
D ) 
PI ( xi , yj ,qSD 
D ) 
  
  
  
  
  
  
j 
i  
  
  
  QD 
 
P(QE = qS E 
E )  l(xi , yj , tqSE 
E ) PI (Lm
I ,fn xi , yj ,qSD 
D ) 
QE 
  
  
  
or, again using nxi ,y j 
I ( tqS ) = l(xi , yj ,t qS ) PI( xi , yj ,qS ) 
E n I (t, Lm
I ,fn Q) [ ]= P(QD = qSD 
D ) 
PI (Lm I
,fn xi , yj ,qSD 
D ) 
PI ( xi , yj ,qSD 
D ) 
  
  
  
  
  
  
j 
i 
E n xi , yj 
I ( tqSD 
D ) [ ]   
  
  
  
  
  QD  
(Eq. 11) 
where [ ] ) ( E , 
D 
S 
I 
D j y i x tq n is the expected value of n xi, y j 
I (t) conditional on the set of dike parameters 
qSD 
D . The form of Equation 11 greatly improves the efficiency of the calculation because the 
terms involving the conditional probability of intersection need to be computed only once for 
each dike parameter set, qSD 
D , rather than for every combination of the parameters qSE 
E that define 
the distribution for volcanic event frequency. 
6.5.1.3 Conditional Distribution for the Number of Eruptive Centers 
This section develops the mathematical formulation for assessing the conditional distribution for 
the number of eruptive centers within the footprint of the proposed repository. The development 
is based on the concept that eruptive centers will occur at uncertain locations along the length of 
the dike associated with a volcanic event. The length of intersection within the proposed 
repository footprint compared to the total length of the dike, the number of eruptive centers per 
volcanic event, and the spatial distribution of eruptive centers along the length of the dike 
provide the bases for assessing the likelihood that one or more eruptive centers will occur within 
the proposed repository footprint. The total length of the dike and the length of intersection 
within the proposed repository are computed as part of the formulation presented in 
Section 6.5.1.2 and are completely defined by the PVHA experts interpretations. The number of 

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eruptive centers per volcanic event and the spatial distribution of eruptive centers along the 
length of a dike were not defined as part of the PVHA expert elicitation. However, with the 
limited set of assumptions (Section 5), these can be derived from the experts interpretations. 
There are alternative ways that these assumptions can be applied. In keeping with the concept of 
uncertainty characterization employed in the PVHA, these alternatives were used to develop 
alternative assessments of the conditional distribution for the number of eruptive centers within 
the proposed repository footprint. These are then combined using relative weights assigned to 
each to produce a composite assessment. 
The assumptions listed in Section 5.1 and 5.2 provide the basis for using the mapped volcanoes 
in the YMR to derive assessments of the number of eruptive centers per volcanic event from the 
PVHA experts interpretations. Two alternative approaches are used. The first approach uses 
the number of mapped volcanoes to derive empirical distributions for the number of eruptive 
centers per volcanic event independent of any assessment of the total length of the dike system 
associated with the volcanic event. In this approach, volcanic events can have from 1 to 
5 eruptive centers, the range in number of individual volcanoes associated with a single volcanic 
event by the PVHA experts using the YMR data. The second approach uses the number and 
location of the mapped volcanoes to derive an assessment of the spacing between eruptive 
centers. The spacing between eruptive centers comb ined with the total length of the dike system 
associated with a volcanic event determines the number of eruptive centers for a given volcanic 
event. Attachment III presents the assessments of the distributions for number of eruptive 
centers per volcanic event and the spacing between eruptive centers. The use of these results is 
described in greater detail in Section 6.5.2.2. 
The calculation of the likelihood of one or more eruptive centers occurring within the proposed 
repository requires specification of the spatial distribution of eruptive centers along the length of 
the dike system. The minimum information model for the random location of a point on a line is 
the uniform distribution between the limits of the line length. The assumption listed in 
Section 5.3 applies the uniform distribution to eruptive center location. Two alternative 
applications of the uniform distribution were used to capture the range of possible behaviors 
when multiple eruptive centers occur along the length of the dike system fo r a single volcanic 
event. 
The first approach specifies the location of each eruptive center independently of the others. 
Over many volcanic events, this approach, on average, will produce eruptive centers spaced out 
over the total length of the volcanic events. However, for an individual event, a range of 
behaviors may occur. Part (a) of Figure 14 shows the results of 20 simulations using this 
approach, designated the independent, uniformly distributed (IUD) approach. Some of the 
simulations produce relatively uniform spaced eruptive centers and some produce highly 
clustered eruptive centers. 
Dense clustering of multiple eruptive centers can be prevented by imposing a minimum spacing 
between the eruptive centers. Taking this approach to the limit would result in uniform spacing 
of eruptive centers along the length of the dike. Part (b) of Figure 14 shows the results of 
20 simulations using a model in which the length of the dike is divided into equal length 
segments, one segment for each eruptive center. Applying the assumption listed in Section 5.3, 
each eruptive center is randomly located within its segment following a uniform distribution. 

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This approach, designated the uniformly spaced, randomly distributed (USRD) approach, 
produces a broader spread between the eruptive centers in each simulation compared with the 
IUD approach, while still allowing for clustering of two eruptive centers along the length of the 
dike. Some clustering is expected to occur on occasion, given the close spacing between Little 
Cones SW and Little Cones NE. 
Using these two approaches for the spatial distribution of eruptive centers, the formulation from 
Section 6.5.1.2 is expanded to define the distribution for the number of eruptive centers that 
occur within the proposed repository. In the previous section, the contributions to the frequency 
of intersection from each location (x,y) in the spatial grid around the proposed repository, 
n xi, y j 
I (tqS ) , were divided into probabilities for intersection with specific lengths and azimuths, 
n xi, y j 
I (t, Lm
I ,fn qS ) . 
This calculation involved looping over the possible dike lengths and azimuths. During this 
calculation, the spatial models described above can be used to compute the number of volcanic 
events that produce 0, 1, 2, 3, etc., eruptive centers in the proposed repository. As a result, 
n xi, y j 
I (t, Lm
I ,fn qS ) is divided into the frequency of intersection from volcanic events at point (x,y) 
that produce specific numbers of eruptive centers within the proposed repository, 
n xi, y j 
I (t, Lm
I ,fn , r ECqS ). Summing these values over all locations (x,y) gives the frequency of 
intersection with a specific number of eruptive centers in the proposed repository, 
n I (t,Lm
I , fn , r ECqS ). Dividing this frequency by the total frequency of intersection, n I (tqS ) , 
gives the conditional probability that an intersecting event will produce a specific number of 
eruptive centers in the proposed repository. 

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N/A - For Illustration Purposes Only 
NOTE: The solid triangles show the locations of five eruptive centers for each simulation. 
Figure 14. Example Simulations of the Distribution of Eruptive Centers Along the Length of a Dike for: 
(a) the Independent, Uniformly Distributed Spatial Distribution and (b) the Uniformly Spaced, 
Randomly Distributed Spatial Distribution 
The disaggregation of n xi, y j 
I (t, Lm
I ,fn qS ) into n xi, y j 
I (t, Lm
I ,fn , r ECqS ) for rEC = 0, 1, 2,  eruptive 
centers is accomplished by computing the conditional distribution for rEC, given the total length 
of the dike, L, the length of intersection within the proposed repository footprint, LI, the number 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 72 Septemb er 2003 
of eruptive centers associated with the volcanic event, nEC, and the spatial distribution for the 
location of eruptive centers. Note that the assumption listed in Section 5.2 results in nEC1. 
Independent, Uniformly Distributed (IUD) Spatial Distribution 
In this approach, the location of each eruptive center is uniformly distributed along the total 
length of the dike and the location of each eruptive center is independent of all of the others. 
Thus, the occurrence of each eruptive center within the footprint of the proposed repository is an 
independent Bernoulli trial with probability of success, p, equal to the length of intersecting dike 
within the proposed repository, LI, divided by the total length of the dike, L. Under these 
conditions, the conditional probability distribution for the number of eruptive centers within the 
proposed repository footprint, rEC, given nEC eruptive centers associated with the volcanic eve nt, 
is given by the binomial distribution: 
PIUD (r EC nEC,L,LI ) = 
nEC 
r EC 
  
  
    
  
  LI 
L 
  
  
    
 
r EC 
1- 
LI 
L 
  
  
    
 
nEC -r EC 
(Eq. 12) 
where 
n EC 
r EC 
  
  
    
  
  is the binomial coefficient and the subscript IUD refers to independent, uniformly 
distributed eruptive centers. 
Uniformly Spaced, Randomly Distributed (USRD) Spatial Distribution 
The alternative approach for the spatial distribution of eruptive centers is that they are spaced 
more or less equal-distant along the length of the dike. If nEC eruptive centers are generated 
along the length of the dike, then each eruptive center is located within a segment of length Ls = 
L/nEC. If the location of the eruptive center within each segment is defined by a uniform 
distribution, the probability that an eruptive center associated with segment q will occur within 
the proposed repository footprint is equal to the length of segment q within the boundary of the 
proposed repository, LsI
q, divided by the total length of the segment, Ls
q. There can be at most 
two segments of a dike that have partial penetration of the proposed repository footprint in one 
volcanic event (there may be more segments that lie entirely within the proposed repository 
footprint). If only the qth segment penetrates into the proposed repository footprint, then the 
probabilities for zero or one eruptive center within the proposed repository are given by: 
PUSRD( r EC = 0 n EC, L,LI ) = 1- 
Lq
sI 
Lq
s 
PUSRD( rEC =1 nEC, L, LI ) = 
Lq
sI 
Lq s 
(Eq. 13) 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 73 Septemb er 2003 
If the qth and (q+1)th segments penetrate into the proposed repository footprint, then the 
probabilities for zero, one, or two eruptive centers within the proposed repository are given by: 
PUSRD(r EC = 0 nEC, L, LI ) = 1- 
Lq
sI 
Lq s 
  
  
  
  
  
  1 - 
Lq+1 
sI 
Lq+1 
s 
  
  
  
  
  
  
PUSRD( r EC =1nEC, L,LI ) = 
Lq
sI 
Lq
s 
  
  
  
  
  
  1 - 
Lq +1 
sI 
Lq +1 
s 
  
  
  
  
  
 + 1 - 
Lq
sI 
Lq
s 
  
  
  
  
  
  
Lq +1 
sI 
Lq +1 
s 
  
  
  
  
  
  
PUSRD(r EC = 2nEC,L, LI ) = 
Lq
sI 
Lq s 
  
  
    
  
  
Lq +1 
sI 
Lq +1 
s 
  
  
    
  
  
(Eq. 14) 
If one or more segments lie entirely within the proposed repository footprint, then the probability 
of an eruptive center occurring within the proposed repository is unity for these segments. In 
such a case, the value of rEC in Equations 13 and 14 is increased by the number of wholly 
contained segments. For example, if one segment lies completely within the proposed repository 
and one spans the boundary of the proposed repository, then Equation 13 becomes: 
PUSRD(r EC = 0 nEC, L,LI ) = 0 
PUSRD( r EC =1n EC, L,LI ) = 1- 
Lq
sI 
Lq
s 
PUSRD(rEC = 2 n EC,L,LI ) = 
Lq
sI 
Lq s 
(Eq. 15) 
Figures 15a and 15b compare the probabilities obtained from these two approaches to the spatial 
distribution of eruptive centers as a function of dike length, L, for LI = 1 kilometer and nEC = 2 
(Figure 15a) and for LI = 1 kilometer and nEC = 3 (Figure 15b). The figures show the computed 
probabilities for rEC equal to from 0 to nEC, and the probability for at least one eruptive center 
within the proposed repository P(rEC > 0). Note that P(rEC > 0) is equal to the sum of the 
probabilities for rEC equal to from 1 to nEC, and is equal to 1 - P(rEC = 0). For all total lengths, 
the USRD model produces a higher probability for rEC > 0, with the difference between the two 
models diminishing as the dike length increases. Except for short dike lengths, use of the IUD 
spatial distribution produces a higher probability of multiple eruptive centers within the proposed 
repository footprint. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 74 Septemb er 2003 
N/A - For Illustration Purposes Only 
NOTE: Results are shown for the independent, uniform ly distributed (IUD) (Equation 12) and the uniformly 
spaced, randomly distributed (USRD) (Equation 13) spatial distributions. 
Figure 15a. Probability for the Number of Eruptive Centers Within the Proposed Repository Footprint, rEC, 
as a Function of Dike Length, L, for the Length of Intersection, LI = 1 Kilometer and the 
Number of Eruptive Centers Associated with the Volcanic Event, nEC , = 2 
N/A - For Illustration Purposes Only 
NOTE: Results are shown for the independent, uniformly distributed (IUD) (Equation 12) and the uniformly 
spaced, randomly distributed (USRD) (Equation 13) spatial distributions. 
Figure 15b. Probability for the Number of Eruptive Centers Within the Proposed Repository Footprint, rEC, 
as a Function of Dike Length, L, for the Length of Intersection, LI = 1 Kilometer and the 
Number of Eruptive Centers Associated with the Volcanic Event, nEC , = 3 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 75 Septemb er 2003 
Conditional Distribution 
In evaluating the consequences of an intersection of the proposed repository footprint by the dike 
system associated with a volcanic event, it is more informative to define P(rEC) conditional on 
the length of intersection, LI
m. Equation 8 defines the joint probability of intersection length and 
azimuth for a volcanic event at point (xi,yj), PI (Lm
I ,fn xi ,yj ,qSD 
D ). As indicated in developing 
Equation 11, the only parameters that affect the calculation of the conditional probability of 
intersection are D 
S D q . Thus PI (Lm
I ,fn xi ,yj ,qS ) in Equation 8 can be rewritten as 
PI (Lm
I ,fn xi ,yj ,qSD 
D ). In addition, the probability for the number of eruptive centers within the 
proposed repository, Equations 12, 13, and 14, is dependent on the number of eruptive centers 
per volcanic event, nEC. Attachment III develops distributions for nEC, P(nEC = h Lp,qSD 
D ) , which 
may be conditional on the total length of the dike, Lp. The parameter set qSD 
D is expanded to 
include any alternatives for assessing P(n EC = h) . Using these definitions, the joint probability 
of rEC eruptive centers in the proposed repository for a volcanic event at (x,y) producing a length 
of intersection of LI
m at an azimuth of fn is given by: 
PI (Lm I
,fn , rEC xi , yj ,qSD 
D ) = P(Lp qS D 
D ) 
L p = 0 
L p = Lmax q SD 
D 
 P(Eo
L qSD 
D ) d (LI = Lm I
) 
Eo
L = 0 
Eo
L =1 
  P(fnqSD 
D )  
P(nEC = hLp ,qS D 
D )P( rEC Lp, Lm I
,nEC = h) 
h=1 
h= nmax 
EC 
 
(Eq. 16) 
with P(r EC Lp, Lm
I ,nEC = h) given by either Equation 12 or Equations 13 and 14. 
Multiplying Equation 16 by l(xi , yj ,tqSD 
D ) , the frequency of volcanic events at (xi,yj), and 
summing over all locations yields the frequency of occurrence for intersections of the proposed 
repository of length LI
m and azimuth fn with rEC eruptive centers within the repository: 
n I (t,Lm
I , fn , r ECqS ) = l(xi , yj ,t q SE 
E )  PI (Lm
I ,fn ,r EC xi , yj ,qSD 
D ) 
j 
i  
(Eq. 17) 
Because the summation of n I(t,LI
m,fn,rEC|qS) over rEC = 0 to rEC = EC 
max n equals nI(t,LI
m,fn|qS), the 
ratio n I(t,LI
m,fn,rEC|qS)/n I(t,LI
m,fn|qS) defines the relative frequency of intersection events with 
length LI
m and azimuth fn. that produce rEC eruptive centers within the proposed repository. 
In the same manner that Equation 9 was recast as Equation 10, Equation 17 can be recast into the 
form: 
n I (t,Lm
I , fn , r ECqS ) = nx i , yj 
I (tqSE 
E ,qSD 
D ) 
j 
i 
 
PI(Lm 
I ,fn, r EC xi , yj ,qSD 
D ) 
PI( xi , yj ,qSD 
D ) 
  
  
  
  
  
  (Eq. 18) 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 76 Septemb er 2003 
where the substitution n xi, y j 
I (tqSE 
E ,qSD 
D ) = l (xi , yj ,t qSE 
E )  PI ( xi ,yj ,qSD 
D ) has been made. Equation 18 
may be adapted in a manner similar to Equation 11 to improve the efficiency of the computation 
of the expected value of n I(t,LI
m,fn,rEC|qS), producing: 
E n I (t, Lm
I ,fn,r EC Q) [ ]= P(QD = qSD 
D ) 
QD 
 
PI (Lm
I , fn, r EC xi , yj ,qSD 
D ) 
PI ( xi , yj ,qSD 
D ) 
  
  
  
  
  
  
j 
i 
E nxi , yj 
I (t qSD 
D ) [ ]   
  
  
  
  
  
(Eq. 19) 
6.5.2 Implementation 
This section describes the implementation of the formulation presented in Section 6.5.1. 
Equations 3 and 5 provide the relationships used to compute the frequency of intersection, nI(t). 
Equations 10, 11, 18, and 19 provide the relationships used to compute the frequency of 
intersecting volcanic events that produce an intersection length of LI
m, at an azimuth of fn, with 
rEC eruptive centers occurring within the proposed repository footprint. 
6.5.2.1 Frequency of Intersection of the Proposed Repository Footprint by a Dike 
The computational scheme used in CRWMS M&O (1996 [100116]) and repeated in this report 
consists of the steps shown on Figure 1 (repeated for each experts interpretation). 
Step 1: Discrete cumulative distributions for dike length are developed from the experts 
assessments using software routines FITCD V1.0 (STN: 10262-1.0-00 [148532]) or SFCD V1.0 
(STN: 10275-1.0-00 [148533]) [e.g., part (a) of Figure 13]. These are then convolved with the 
event location of the dike on the volcanic event [e.g. part (b) of Figure 13] to produce 
distributions for volcanic event length [e.g. part (c) of Figure 13] using software routine 
DCPELD V1.0 (STN: 10258-1.0-00 [148534]). 
Step 2: The conditional probability of intersection, PI ( xi , yj ,qSD 
D ) , is computed for each set of 
parameters qSD 
D (defined by an unique event length distribution from step 1 and an unique 
azimuth distribution) using software routine CPDI V1.0 (STN: 10257-1.0-00 [148535]). 
Step 3: The rate of intersection, n I(t), is computed using software routines specific to the type of 
source [software routines UZVH V1.0 (STN: 10277-1.0-00 [148536]) and UZVPVH V1.0 
(STN: 10279-1.0-00 [148537]) for source zones; routines FKVH V1.0 (STN: 10265-1.0-00 
[148567]), FKVPVH V1.0 (STN: 10267-1.0-00 [148538]), and ZBCKVH V1.0 (STN: 10283- 
1.0-00 [148539]) for kernel density sources; and routines PFGVH V1.0 (STN: 10273-1.00-00 
[144542]) and FPFGVH V1.0 (STN: 10269-1.0-00 [148543]) for 2-D Gaussian field sources]. 
The characterization of individual volcanic sources is defined by a 12-parameter subset of qSE 
E . 
The distribution for these parameters depends upon the alternative source definitions, temporal 
models, and time periods of interest. To denote this breakdown of qSE 
E , the parameter set qS ASM 
E 
represents the alternative source models (including temporal models) and parameter set 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 77 Septemb er 2003 
qS ISP 
E qSASM 
E represents the individual source parameters, which are conditional on the chosen 
source and temporal models qS ASM 
E . The software routines used to compute the hazard from an 
individual source contain a set of 12 nested DO loops to enumerate all of the alternative versions 
of qS ISP 
E qSASM 
E (see Figure 11b). Given a set of parameters, the frequency of volcanic events, 
la (xi , yj ,tqSISP 
E ) , is computed for a specific source, a, using the formulation appropriate for the 
source type. This is multiplied by the conditional probability of intersection, PI ( xi , yj ,qSD 
D ) , 
from the output of routine CPDI V1.0 and summed over all points within the source to obtain the 
frequency of intersection from volcanic events associated with source a. The software routines 
store the mean frequency of intersection and the distribution in the frequency of intersection 
(computed over the distributions for qS ISP 
E qSASM 
E in output files for use in the final step of the 
computations. Separate output files are created for all of the alternative sets of source model 
parameters, qS ASM 
E , and for the alternative parameters that describe the associated dikes, qSD 
D . 
Step 4: The results from step 3 are combined over the distributions for qS ASM 
E and qSD 
D 
(see Figures 11a and 11b) to compute the full distribution for frequency of intersection specified 
by an individual PVHA experts interpretations. The results for each expert are then combined 
to obtain the composite distribution. These calculations are performed using software routine 
VHTREE V1.0 (STN: 10282-1.0-00 [148544]). Complete enumeration of all of the alternative 
parameter sets qS ASM 
E is again achieved by a series of nested DO loops. The mean value and 
various percentiles of the distribution for frequency of intersection of the proposed repository 
footprint by a dike were computed from the discrete distribution for nI(t|qSD 
D ,qSE 
E ) as described 
above in Section 6.5.1.1. These are then combined using equal weights to produce a composite 
distribution for frequency of intersection. 
The proposed LA repository footprint used for the calculations in this report is shown in 
Figure 16a. The calculations performed in the PVHA (CRWMS M&O 1996 [100116]) used the 
proposed repository footprint shown in Figure 16b. The LA repository design calls for a longer 
and narrower emplacement area compared to the design used at the time of the PVHA 
(Figure 16b). Attachment II presents the coordinates of the drifts in the proposed LA repository 
footprint and their transformation to UTM kilometers. The polygon used for calculations in this 
report was constructed to provide a clearance of approximately 55 m around the drift coordinates 
(see Figur e 16a) to account for the effect of the size of eruptive centers in the calculations 
(see Attachment III). The polygon encompasses emplacement panels 1, 2, 3, and 5 of the current 
IED design (BSC 2003 [162289]) and was used to calculate the conditional distributions for 
intersection length, azimuth, and number of eruptive centers using the simulation approach 
developed in this report. This polygon was also used to calculate an updated mean and 
distribution for the frequency of intersection of the proposed LA repository footprint by a dike 
using the full enumeration approach employed in the PVHA (CRWMS M&O 1996 [100116]). 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 78 Septemb er 2003 
DTN: LA0303BY831811.001 [163985] 
Figure 16a. Proposed License Application Emplacement Drifts and Footprint Polygon Encompassing 
Emplacement Panels 1, 2, 3, and 5 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 79 Septemb er 2003 
DTN: LA0303BY831811.001 [163985] 
NOTE: PVHA reference in figure is CRWMS M&O (1996 [100116]). 
Figure 16b. Location of Proposed License Application Repository Footprint Compared to Repository 
Footprint Used in the Probabilistic Volcanic Hazard Analysis 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 80 Septemb er 2003 
6.5.2.2 Distributions for Length, Azimuth, and Number of Eruptive Centers 
The computations performed in CRWMS M&O (1996 [100116]) were made for all possible sets 
of qSD 
D and qSE 
E defined by the volcanic hazard characterization of each of the PVHA experts 
[full enumeration of the logic tree branches (CWRMS M&O 1996 [100116], Appendix E)]. 
However, the objective of this analysis is a disaggregation of the intersection frequency, 
n I(t|qSD 
D ,qSE 
E ), into intersection frequencies with specific values of LI
m, fn, and rEC . Repeating the 
calculation for the spatial disaggregation would require exhaustive computation and storage of 
the spatial disaggregation of the hazard, n xi, y j 
I (t qSE 
E ,qSD 
D ) , for all possible parameter sets qSE 
E . 
Therefore, a simulation approach was used to develop random sample parameter sets qSE 
E from 
the PVHA experts logic trees to speed up the computation process. As discussed subsequently 
in the results (Section 6.5.3), the mean and distribution for the frequency of intersection of the 
proposed repository footprint by a dike computed by full enumeration and by simulation for each 
PVHA experts interpretation and for the composite result generally agree within a few percent. 
The approach used to obtain the spatial disaggregation of the frequency of intersection consists 
of the following steps (see Figure 2). 
Step 1: The conditional probability of intersection, PI ( xi , yj ,qSD 
D ) , was taken directly from the 
computation for the frequency of intersection discussed above. The files containing 
PI ( xi , yj ,qSD 
D ) for each set of parameters qSD 
D were created using routine CPDI V1.0 
(STN: 10257-1.0-00 [148535]) using inputs processed through routines FITCD V1.0 
(STN: 10262-1.0-00 [148532]), SFCD V1.0 (STN: 10275-1.0-00 [148533]), and DCPELD 
V1.0 (STN: 10258-1.0-00 [148534]). 
Step 2: The second step in the calculation involved computation of the spatial disaggregation of 
frequency of intersection hazard for the individual sources specified by the alternative source 
parameter sets qS ASM 
E and for the alternative dike parameters qSD 
D . For the reasons discussed 
above, simulation is used to select random samples of the parameter subset qS ISP 
E qSASM 
E used to 
compute the frequency of intersection for an individual source type. The approach used to 
generate these parameter subsets is Latin hypercube sampling (McKay et al. 1979 [127905], 
pp. 243245). The software routines used to compute the frequency of intersection replace the 
12 nested DO loops with simulation of 50 parameter sets, qsimISP 
E qSASM 
E , simISP = 1K50 , using 
Latin hypercube sampling from the 12 independent, discrete parameter distributions that define 
QISP 
E qSASM 
E . Once a parameter subset is defined, the spatial distribution of l(x,y,t) for source a is 
computed using the same algorithms employed for the PVHA calculation (CRWMS M&O 1996 
[100116]). The disaggregated frequency of intersection, na, xi , yj 
I (t qsimISP 
E ,qSASM 
E ,qSD 
D ), from each 
simulation for each source a is output to a file along with the mean frequency of intersection for 
the source. Each simulated parameter set qsimISP 
E qS ASM 
E is an equally likely realization of the 
possible parameter sets from the joint distribution for QISP 
E qSASM 
E . Therefore, the mean frequency 
of intersection for source a, given source model parameter set qS ASM 
E and dike parameters qSD 
D , 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 81 Septemb er 2003 
E na I
(tqS ASM 
E , qSD 
D ) [ ], and its spatial disaggregation [ ] ) , ( E , , 
D 
S 
E 
S 
I 
y x D ASM j i 
t q q na , may be estimated by the 
average of the results from the 50 simulations. 
E na I
(tqSASM 
E ,qS D 
D ) [ ]~ 
1 
50 
na I
(tqsimISP 
E ,qS-ASM 
E , qSD 
D ) 
sim ISP =1 
simISP =50 
 
and 
E na,xi ,yj 
I (tqSASM 
E ,qS D 
D ) [ ]~ 
1 
50 
na ,x i ,y j 
I (t qsimISP 
E ,qS- ASM 
E ,qSD 
D ) 
sim ISP =1 
simISP =50 
 
(Eq. 20) 
The simulation software routines are designated UZVHLH V1.0 (STN: 10278-1.0-00 
[1485454), UZVPVHLH V1.0 (STN: 10280-1.0-00 [148547]), FKVHLH V1.0 
(STN: 10266-1.0-00 [148546]), FKVPVHLH V1.0 (STN: 10268-1.0-00 [148551]), 
ZBCKVHLH V1.0 (STN: 10284-1.0-00 [148550]), PFGVHLH V1.0 (STN: 10274-1.0-00 
[148552]), and FPFGVHLH V1.0 (STN: 10270-1.0-00 [148553]). They use the same input files 
used to compute the frequency of intersection by full enumeration (Section 6.5.2.1). 
Step 3: The third step in the calculation is computation of the distribution for the spatial 
disaggregation of the hazard for each the PVHA experts interpretation. The full enumeration of 
the possible parameter sets qSD 
D and qS ASM 
E is again replaced by simulation of 50 equally likely 
parameter sets. The software routine VHTIELHS V1.0 (STN: 10281-1.0-00 [148554]) is used 
to perform the following operations for the interpretation developed by each of the PVHA 
experts. 
Step 3a. First, all of the possible sets qSD 
D ,qS ASM 
E in the joint distribution for QD and QASM 
E are 
enumerated. The joint probability of each set is computed from the PVHA experts logic tree. 
Step 3b. The mean frequency of intersection for each set of qSD 
D ,qS ASM 
E and its spatial 
disaggregation are estimated from the sum of all the individual source results from Step 2, for 
those sources present in the parameter set qS ASM 
E , 
E n I (t qS ASM 
E ,qSD 
D ) [ ]~ E na I
(tqSASM 
E ,qSD 
D ) [ ] 
a qSASM 
E  
and 
E nx i ,y j 
I (t qS ASM 
E ,qSD 
D ) [ ]~ E na, x i, y j 
I (t qSASM 
E , qSD 
D ) [ ] 
a qSASM 
E  
(Eq. 21) 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 82 Septemb er 2003 
Step 3c. The sets of qSD 
D ,qS ASM 
E are then ranked in terms of increasing mean frequency of 
intersection, E n I (tqSASM 
E , qSD 
D ) [ ], defining a distribution for E n I (tqSASM 
E , qSD 
D ) [ ]. 
Step 3d. Then, 50 parameter sets, qsimD 
D ,qsim ASM 
E , are selected using Latin hypercube sampling 
from the distribution for E n I (tqSASM 
E , qSD 
D ) [ ]. For each of these, the frequency of intersection and 
its spatial disaggregation are computed for the 50 simulations of parameters qsimISP 
E qS ASM 
E =qsimASM 
E ( ) 
by: 
n I (tqsim ISP 
E ,qsimASM 
E ,qsim D 
D ) ~ na I
(t qsim ISP 
E ,qsimASM 
E , qsimD 
D ) 
a qsim ASM 
E  
and 
n xi , yj 
I (tqsim ISP 
E ,qsimASM 
E ,qsim D 
D ) ~ na ,x i ,y j 
I (t qsimISP 
E ,qsim ASM 
E ,qsimD 
D ) 
a qsim ASM 
E  
(Eq. 22) 
In Equation 22, na
I (tqsimISP 
E , qsimASM 
E ,qsimD 
D ) , and its spatial disaggregation, 
na, xi , yj 
I (t qsim ISP 
E ,qsimASM 
E , qsimD 
D ), are the values for source a for the simulated parameter set 
qsimISP 
E qSASM 
E ,qS D 
D from (2) with qS ASM 
E ,qSD 
D = qsimASM 
E ,qsimD 
D , the source model and dike parameter set 
selected in one simulation. The result is 2,500 equally likely values for frequency of 
intersection. The resulting values of the spatial disaggregatio n of the frequency of intersection, 
n xi, y j 
I (tqsimISP 
E ,qsimASM 
E ,qsimD 
D ), are written to separate files for each of the 2,500 simulated parameter 
sets. 
Step 3e. Finally, the expected value for the spatial disaggregation of the frequency of 
intersection for each of the possible dike parameter sets is estimated from the average of all of 
the results from step 3d for which qsimD 
D =qSD 
D . 
E n xi ,y j 
I (tqS D 
D ) [ ]~ 
nxi ,y j 
I (t qsimISP 
E ,qsimASM 
E ,qsimD 
D ) d(qsim D 
D = qSD 
D ) 
sim ISP, ASP,D =1 
sim ISP, ASP,D =2500 
 
d(qsimD 
D = qSD 
D ) 
simISP,ASP, D=1 
simISP,ASP, D= 2500 
 
(Eq. 23) 
where d (qsimD 
D = qS D 
D ) = 1 for those simulations where qsimD 
D =qSD 
D , and zero otherwise. Note that 
1 
2,500 d(qsim D 
D = qSD 
D ) 
sim ISP, ASP,D =1 
simISP, ASP,D = 2500 
 ~ P(QD = qSD 
D ) .] 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 83 Septemb er 2003 
Figure 17, part (b), shows a map of E nx i ,y j 
I (t qSD 
D ) [ ] averaged across all 10 experts. This figure 
indicates the locations of volcanic events that contribute to the frequency of intersection. Also 
shown on Figure 17, part (a), is a map of the expected frequency of volcanic events, 
E l(xi , yj ,tqSD 
D ) [ ], averaged across all experts. This map was obtained by repeating the 
calculation for part (a) with the conditional probability of intersection, PI ( xi , yj ,qSD 
D ) , set to 1 at 
every point (x,y). 
The previous version of this analysis report (Revision 00 ICN 01) recalculates the frequency of 
intersection using the 70,000 metric tons of uranium (MTU) No-Backfill layout shown on 
Figure 16a. Figure 17a shows the revised map of E nx i ,y j 
I (t qSD 
D ) [ ] averaged across all 10 experts. 
Step 4: The composite distribution for the frequency of intersection of the proposed repository 
footprint by a dike is now represented by the 2,50010 simulation results for the 10 PVHA 
experts. Each experts distribution was assigned equal weight in the PVHA aggregation process. 
Thus, the composite 25,000 simulations of n I(t) are all equally likely. The 25,000 simulations of 
n I(t) are ranked and the simulations that produce various percentile of the distribution for n I(t) 
are identified (e.g., the 95th percentile is the simulation with rank 0.9525,000 = 23,750). 
Simulation results that are close to each percentile (within a rank of 250) that are for different 
experts are also identified to capture the range of expert interpretations. These simulations are 
identified using software routine CFRAC V1.0 (STN: 10254-1.0-00 [148560]). 
Step 5: Steps 1 through 4 provide the values of n xi, y j 
I (tqsimISP 
E ,qsimASM 
E ,qsimD 
D ) and E nx i ,y j 
I (t qSD 
D ) [ ] 
needed for Equations 10, 11, 18, and 19. What remains is the calculation of PI (Lm
I ,fn xi ,yj ,qSD 
D ) 
and PI (Lm
I ,fn , rEC xi , yj ,qSD 
D ) , the discretization of the conditional probability of intersection into 
increments of intersection length, intersection azimuth, and number of eruptive centers within the 
proposed repository footprint for each volcanic event location (x,y). Software routine 
DILECDLH V1.0 (STN: 10259-1.0-00 [148559]) is used to discretize the conditional 
probability of intersection, PI ( xi , yj ,qSD 
D ) , into the designated bins for length and azimuth within 
the proposed repository. The inputs to program DILECDLH are: (1) the spatial disaggregation 
of the frequency of intersection (either the mean result conditional on qSD 
D for one expert from 
Step 3 or for one of the hazard simulations representative of the 95th percentile of the composite 
distribution from Step 4); (2) the dike length and volcanic event location distributions for the 
corresponding parameter set qSD 
D ; (3) a joint distribution for dike length and the number of 
eruptive centers on a dike, P(nEC = h Lp,qSD 
D ) [computed using software routines FITIDSR V1.0 
(STN: 10264-1.0-00) [148557], SFIDSR V1.0 (STN: 10276-1.0-00 [148571]), and DLECD 
V1.0 (STN: 10260-1.0-00 [148558]); and (4) the spatial distribution of eruptive centers along 
the dike. With the exception of the assessments for the number and spatial distribution of 
eruptive centers, all of the probability distributions required to perform this calculation are 
defined in CRWMS M&O (1996 [100116]). 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 84 Septemb er 2003 
Output DTN: (Figure 17a) LA0009FP831811.001 [164712]; DTN: (Figure 17b) LA0303BY831811.001 [163985]. 
NOTE: The maps represent the mean results averaged over 10 experts and over each experts logic tree 
(CRWMS M&O 1996 [100116], Appendix E). Black area in center of maps is the location of the 
proposed repository. 
Figure 17. Spatial Distribution of Volcanic Hazard Defined by the Probabilistic Volcanic Hazard Analysis 
Expert Panel: (a) Map of Expected Volcanic Event Frequency and (b) Map of Spatial 
Disaggregation of Expected Intersection Frequency 
Two alternative approaches are developed for the spatial distribution of eruptive centers in 
Section 6.5.1.3. In the first approach (designated IUD) the location of each eruptive center is 
specified by an independent, uniform distribution over the total length of the dike, Lp. In the 
second approach (designated USRD) the eruptive centers are spaced out over the full length of 
the dike with the location each of the nEC eruptive centers uniformly distributed in a segment of 
length Lp/nEC. Calculations of PI (Lm
I ,fn , rEC xi , yj ,qSD 
D ) are performed for both approaches. 
Distributions for the number of eruptive centers on a dike, P(nEC = h Lp,qSD 
D ) , are developed 
below from the PVHA experts assessments of the number of eruptive centers associated with a 
volcanic event. 
Each of the PVHA experts made assessments for the number of volcanic events represented by 
the observed Quaternary eruptive centers. For example, the observed five volcanoes in Crater 
Flat may have been caused by 1 to 5 volcanic events, with each expert providing a probability 
distribution for the number of volcanic events. These assessments can be used to produce a 
distribution for the number of eruptive centers per volcanic event. For example, if Crater Flat 
contains five individual volcanic events, then the data indicate one eruptive center per volcanic 
Volcanic Events 
per year 
per sq km 
Intersection 
Events 
per year 
per sq km 
(a) (b) 
500 550 600 
UTM Easting (km) 
4000 
4050 
4100 
4150 
UTM Northing (km) 
1E-013 
1E-012 
1E-011 
1E-010 
1E-009 
1E-008 
1E-007 
500 550 600 
UTM Easting (km) 
4000 
4050 
4100 
4150 
UTM Northing (km) 
1E-016 
1E-015 
1E-014 
1E-013 
1E-012 
1E-011 
1E-010

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 85 Septemb er 2003 
event. If, on the other hand, the five volcanoes (and their associated eruptive centers) were 
created by one volcanic event, then the data indicate five eruptive centers per volcanic event. 
Using each experts assessments of volcanic event counts and the number of separate eruptive 
centers that have occurred in the Quaternary, distributions for the number of separate eruptive 
centers per volcanic event were developed. These are presented in Attachment III and shown in 
Figure 18. 
The distributions for P(nEC = h Lp,qSD 
D ) derived in Attachment III are marginal distributions in 
the sense tha t they are defined independent of assessments of dike length and are averaged over 
an experts interpretations, QE . The experts assessed distributions for dike length are also 
marginal distributions. However, the calculations need to use the conditional distribution of 
number of eruptive centers given dike length. The limiting conditions that define the 
relationship between two variable parameters are complete independence and complete 
dependence. These two limiting conditions are used to define the influence of dike length on 
P(nEC = h Lp,qSD 
D ) . Complete independence implies that the conditional distribution for number 
of eruptive centers is equal to the marginal distribution, and P(nEC = h Lp,qS D 
D ) = P(nEC = hQE ) 
is used in Equation 16. The resulting discretizations of the frequency of intersection are 
designated: n IUD-UC 
I (t,Lm
I ,fn, rEC qS ) for independent, uniformly distributed spatial locations with 
the number of eruptive centers uncorrelated with dike length; and nUSRD-UC 
I (t, Lm
I ,fn, r ECqS ) for 
uniformly spaced, randomly distributed spatial locations with the number of eruptive centers 
uncorrelated with dike length. 
Complete dependence implies that the number of eruptive centers varies directly with dike length 
(it is considered unrealistic to have a negative correlation). The correlation between dike length 
and number of eruptive centers per event was set to the maximum value by making the marginal 
distributions for dike length and number of eruptive centers per volcanic event rank correlated. 
This is achieved by specifying a one-to-one correspondence of the marginal CDFs for the two 
parameters. The resulting discretizations of the frequency of intersect are designated: 
n IUD-C 
I (t, Lm
I ,fn , r ECqS ) for independent, uniformly distributed spatial locations and the number of 
eruptive centers correlated with dike length; and nUSRD-C 
I (t,Lm
I ,fn, rEC qS ) for uniformly spaced, 
randomly distributed spatial locations and the number of eruptive centers correlated with dike 
length. These two approaches span the range of correlation considered reasonable (zero to 
maximum). 
The longest proposed single-event dike represented by the Quaternary volcanoes in the YMR is 
the 11.2-kilometer spacing between Little Cones SW and Makani Cone in Crater Flat. However, 
many of the PVHA experts specified distributions for dike length with upper tails that greatly 
exceed this length. Thus, the distributions presented in Attachment III may not be representative 
of conditions for very long dikes. To address this issue, an alternative approach for defining the 
number of eruptive centers was included in which the number of eruptive centers is defined as an 
average density per kilometer of dike length, or equivalently, by the average spacing between 
eruptive centers. For a given dike length, the number of eruptive centers is found by dividing the 
dike length by the average spacing (rounding to the nearest integer). Consistent with the number 
of eruptive centers being defined by an average spacing between eruptive centers, the USRD 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 86 Septemb er 2003 
spatial distribution is used. The resulting spatial distribution approach is designated Uniformly 
Spaced, Randomly Distributed Fixed Density (USRD-FD) for uniformly spaced, randomly 
distributed with fixed density. 
OUTPUT DATA. DTN: LA0009FP831811.001 [164712] 
NOTE: The two-letter code refers to the initials of the 10 PVHA experts in Table 11. 
Figure 18. Distributions for Number of Eruptive Centers per Volcanic Event, nEC, Derived from the 
Probabilistic Volcanic Hazard Analysis Experts Interpretations (from Attachment III, 
Figure III-1) 
The same process used to derive the distribution for number of eruptive centers per volcanic 
event from the PVHA experts assessments was to be used to evaluate the average spacing 
between eruptive centers. For example, if the five volcanoes in Crater Flat are considered to 
constitute a single volcanic event, then the 11.2-km distance between Little Cones SE and 
Makani Cone in Crater Flat divided by 4 (the number of intervals between eruptive centers) 
gives an average spacing of 2.8 km. The other Quaternary volcano cluster with multiple cones is 
Hidden Cone and Little Black Peak near Sleeping Butte, 2.5 km apart. If these are considered to 
be the result of a single volcanic event, the average spacing between eruptive centers for this 
event is 2.5 km. If these are the only two volcanic events with multiple eruptive centers, then 
one obtains an average spacing for all volcanic events of 2.6 km. An alternative assessment 
might be that Crater Flat contains two volcanic events. One volcanic event may consist of 
Makani and Black Cones. These two cones are located 5.4 km apart. The other volcanic event 
would then consist of Red Cone and the two Little Cones. The distance between Red Cone and 
Little Cone SW is 3.2 km, resulting in an average spacing for this volcanic event of 1.6 km. The 
average eruptive center spacing for the three volcanic events would then be 3.1 km. Using each 
experts assessments of volcanic event counts and the number of separate eruptive centers that 
have occurred in the Quaternary, the average spacing of eruptive centers was computed. These 
are presented in Attachment III and are summarized in Table 14. 
0 
0.1 
0.2 
0.3 
0.4 
0.5 
0.6 
0.7 
0.8 
0.9 
1 2 3 4 5 
Number of Eruptive Centers per Volcanic Event 
Probability 
AM 
BC 
GT 
GW 
MK 
MS 
RC 
RF 
WD 
WH

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 87 Septemb er 2003 
Table 14. Average Eruptive Center Spacing (from Attachment III, Table III-12) 
PVHA Expert 
Average Spacing Between 
Eruptive Centers 
(km) 
Alex McBirney (AM) 2.7 
Bruce Crowe (BC) 1.9 
George Thompson (GT) 1.5 
George Walker (GW) 1.4 
Mel Kuntz (MK) 2.4 
Michael Sheridan (MS) 2.5 
Richard Carlson (RC) 2.4 
Richard Fisher (RF) 2.5 
Wendell Duffield (WD) 1.4 
William Hackett (WH) 2.0 
OUTPUT DATA. DTN: LA0009FP831811.001 [164712] 
The values listed in Table 14 are used as an alternative approach to obtaining nEC. For each 
simulation of a dike length, Lp, the value of nEC is set to Lp divided by the average spacing from 
Table 14, with the quotient rounded to the nearest integer. 
Figure 19 compares the probability of the occurrence of rEC = 0, 1, 2, and rEC > 0 [P(rEC > 0) is 
equal to 1- P(rEC = 0) and is the sum of P(rEC = 1), P(rEC = 2),] eruptive centers computed 
using the USRD-FD spatial distribution and an average eruptive center spacing of 2.5 km with 
the probabilities shown on Figure 15a for the IUD and URSD spatial distribution approaches. 
For short dike lengths, the USRD-FD approach results in a lower probability for one or more 
centers within the proposed repository than the other two approaches. However, as the dike 
length increases, the USRD-FD approach reaches a nearly constant probability of 0.4 for rEC = 1 
[0.4 = (LI = 1)/2.5 kilometer average spacing of eruptive centers]. The oscillations in the 
probability about 0.4 are a result of incremental changes in nEC by integer values as the length of 
the dike increases. The USRD-FD approach produces a density of eruptive centers per volcanic 
event for all dike lengths that is similar to that observed for the Quaternary volcanoes in the 
YMR. The resulting discretization of the frequency of intersection is designated 
nUSRD-FD 
I (t, Lm
I ,fn, r ECqS ) for uniformly spaced, randomly distributed spatial locations, with the 
number of eruptive centers determined by an average spacing between eruptive centers along a 
dike. 

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ANL-MGR-GS-000001 REV 01 88 Septemb er 2003 
N/A - For Illustration Purposes Only 
Figure 19. Probability for the Number of Eruptive Centers Within the Proposed Repository Footprint, rEC, 
Computed Using the Uniformly Spaced, Randomly Distributed Fixed Density Spatial 
Distribution of Eruptive Centers and for the Length of Intersection, LI = 1 km, and an Average 
Spacing of 2.5 km Between Eruptive Centers Compared to the Results for the IUD and USRD 
Models Shown in Figure 15a 
The computation procedure used in software routine DILECDLH V1.0 is as follows: 
Step 5a. An input file is created that contains the probability distributions for the length of the 
dike, L, and number of eruptive centers per volcanic event, nEC. The probability distribution for 
L is discretized into the probability mass for Lp in 0.05 kilometer increments using module 
FITIDSR V1.0 (STN: 10264-1.0-00 [148557]) or SFIDSR V1.0 (STN: 10276-1.0-00 
[148571]). The marginal distribution for nEC is listed at the top of the file and the rank correlated 
value for nEC is listed for each value of L by determining the value in the marginal distribution 
for nEC that has the same cumulative probability as Lp in the marginal distribution for L. 
Step 5b. For each of the dike parameter sets, qSD 
D , the spatial disaggregation of the hazard 
computed in Steps 3 and 4 is then input into the program. At each location (x,y) that contributes 
to the frequency of intersection {n xi, y j 
I (tqsimISP 
E ,qsimASM 
E ,qsimD 
D ) or E nx i ,y j 
I (t qSD 
D ) [ ] > 0}, the direction 
toward the proposed repository is sampled over 5 increments in azimuth, with the probability 
distribution for PI (fn qSD 
D ) obtained by computing the probability mass in the interval fn-2.5  f 
 fn-2.5. At each azimuth, fn, 100 simulations of Lsim and Esim 
L are created by Latin hypercube 
sampling from the distributions defined for each. For those combinations of Lp and Eo
L at 
azimuth fn that result in intersections with the proposed repository footprint, LI is computed. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 89 Septemb er 2003 
The probability PI (Lm
I ,fn xi ,yj ,qSD 
D ) defined in Equation 8 is now approximated by the 
expression: 
PI (Lm
I ,fn xi ,yj ,qS ) ~ 1 
100 d(LI = Lm
I )  P(fn qS ) (Eq. 24) 
and the probability PI (r EC, Lm
I ,fn xi , yj ,qSD 
D ) in Equation 16 is approximated by 
PI (r EC, Lm I
,fn xi , yj ,qSD 
D ) ~ 1 
100 d(LI = Lm I
) 
sim =1 
sim =100 
 P(fn qS D 
D )  
P(nEC = hLsim,qS D 
D )P(r EC Lsim , Lm I
,nEC = h) 
h=1 
h= nmax 
EC 
 
(Eq. 25) 
where ) ( I
m 
I L L = d = 1 for those simulation values of Lsim and Esim 
L at azimuth fn that result in 
LI=LI
m for a volcanic event at (x,y), and d(LI = Lm
I ) = 0 otherwise. An increment of 0.05 km is 
chosen for the intersection length bin size. This length bin size, together with the azimuth bin 
size of 5 are sufficient to define clearly the variability in the length and azimuth of intersecting 
dikes. (Note that the computation of the frequency of intersection is independent of these bin 
sizes.) Equation 25 is used five times for the five alternative approaches for P(n EC = h Lsim ,qSD 
D ) 
and P(r EC Lsim,Lm
I ,nEC = h) described above. 
Step 5c. The results of step 5b are then used in Equations 11 and 19 to estimate the expected 
frequencies of intersection E n I (t, Lm 
I ,fn Q) [ ] and E n I (t, Lm
I ,fn,r EC Q) [ ], respectively for each of 
the PVHA experts interpretations. The definition for P(QD = qSD 
D ) used in Equation 23 is used 
in this calculation. The results for each expert are then averaged to obtain an estimate of the 
composite expected frequencies over all experts using the expressions: 
E nI (t, Lm I
,fn ) [ ]~ 1 
10 E nI (t,Lm
I ,fn Q) [ ] 
expert 1 
expert 10 
 
and 
E n I (t, Lm
I ,fn,r EC ) [ ]~ 1 
10 E nI (t,Lm
I ,fn ,r EC Q) [ ] 
expert 1 
expert 10 
 
(Eq. 26) 
This calculation is performed using software routine COMBSM V1.0 (STN: 10256-1.0-00 
[148561]). The resulting partial frequencies of intersection are then normalized to produce 
conditional distributions. At each value of LI
m and fn, the computed vales of E n I (t, Lm 
I ,fn, r EC) [ ] 
are divided by E n I (t, Lm
I ,fn ) [ ] to produce a distribution for rEC conditional on LI
m and fn. The 
values of E n I (t, Lm
I ,fn ) [ ] are, in turn, divided by E n I (t) [ ] to produce a joint distribution for LI
m 
and fn conditional on the mean frequency of intersection. Because Latin hypercube sampling 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 90 Septemb er 2003 
was used instead of full enumeration in (2), at a few of the points (x,y) that contribute to the 
frequency of intersection computed in Step 3, the 100 simulated values of Lsim and Esim 
L do not 
produce any intersections. These occur at locations where only the longest possible dikes 
combined with values of L E very near 1.0 result in intersections of the proposed repository 
footprint. As a result, the sum of E n I (t, Lm 
I ,fn Q) [ ] over LI
m and fn for each expert typically 
equaled about 97 percent to 99 percent of E n I (tQ) [ ]. Because the purpose of Step 5 is to obtain 
a conditional distribution, the computed values of E n I (t, Lm 
I ,fn Q) [ ] for each expert were 
normalized in software routine COMBSM V1.0 to sum to the value of E n I (tQ) [ ] computed in 
Step (3). [Note that the true value of E n I (tQ) [ ] was computed by full enumeration of the 
individual expert interpretations.] 
Step 5d. Step 4 identified those simulation results that represented the 5th and 95th percentiles of 
the composite distribution for frequency of intersection. For these parameter sets, designated 
q0.05and q0.95, the results of step 5b are used in Equations 10 and 18 to compute the values of 
n I (t ,Lm
I , fn q 0.05) and n I (t ,Lm
I , fn , r ECq0.05) , respectively, for the 5th percentile hazard and 
n I (t ,Lm
I , fn q 0.95) and n I (t ,Lm
I , fn , r ECq0.95) , respectively, for the 95th percentile hazard. The 
results of the individual simulations are averaged using software routine COMBSF V1.0 
(STN: 10255-1.0-00 [148562]) to produce the final values of n I (t ,Lm
I , fn q 0.05), 
n I (t ,Lm
I , fn , r ECq0.05), n I (t ,Lm
I , fn q 0.95) and n I (t ,Lm
I , fn , r ECq0.95). Routine COMBSF V1.0 
performed this calculation, including the normalization so that the sum of n I (t ,Lm
I ,fn q 0.xx ) over 
LI
m and fn equals n I (t q 0. xx) obtained in Step 4. The resulting disaggregated frequencies of 
intersection are then normalized to produce conditional distributions. At each value of LI
m and 
fn, the computed values of n I (t ,Lm
I , fn , r ECq0.05) are divided by n I (t ,Lm
I , fn q 0.05) and the values 
of n I (t ,Lm
I , fn , r ECq0.95) are divided by n I (t ,Lm
I , fn q 0.95) to produce a distribution for rEC 
conditional on LI
m and fn. The values of n I (t ,Lm
I , fn q 0.05) are, in turn, divided by n I (t q 0.05 ) and 
the values n I (t ,Lm
I , fn q 0.95) are divided by n I (t q 0.95 ) to produce joint distributions for LI
m and fn 
conditional on the 5th and 95th percentile values for the frequency of intersection. 
In summary, the mathematical formulation for computing the conditional distribution for the 
length and azimuth of intersecting dikes within the proposed repository footprint is developed 
directly from the PVHA formulation presented in CRWMS M&O (1996 [100116], Section 3 and 
Appendix E) without invoking any additional assumptions. The formulation for computing the 
conditional distribution for the number of eruptive centers occurring within the proposed 
repository footprint requires additional assumptions in order to assess the number of eruptive 
centers per volcanic event and the spatial distribution of eruptive centers along the length of the 
dike. Five alternative approaches are developed to implement these assumptions to span the 
range of available approaches. Calculations are performed for all five approaches to indicate the 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 91 Septemb er 2003 
sensitivity of the results. As a final step, relative weights are assigned to the five approaches in 
order that a composite result can be obtained. The five approaches are summarized below: 
1. The Independent, Uniformly Distributed, Uncorrelated (IUD-UC) approach. The 
distribution for the number of eruptive centers per volcanic event is derived from the 
PVHA experts interpretations. These distributions are uncorrelated with the 
distributions for dike length. The location for each eruptive center is defined by a 
uniform distribution over the total length of the dike, and if multiple eruptive centers 
occur in a volcanic event, the distributions for their locations are independent. 
2. The Independent, Uniformly Distributed, Correlated (IUD-C) approach. The 
distribution for the number of eruptive centers per volcanic event is derived from the 
PVHA experts interpretations. These distributions are completely correlated with the 
distributions for dike length. The location for each eruptive center is defined by a 
uniform distribution over the total length of the dike, and if multiple eruptive centers 
occur in a volcanic event, the distributions for their locations are independent. 
3. The Uniformly Spaced, Randomly Distributed, Uncorrelated (USRD-UC) approach. 
The distribution for the number of eruptive centers per volcanic event is derived from 
the PVHA experts interpretations. These distributions are uncorrelated with the 
distributions for dike length. The total length of the dike is divided into equal 
segments for each eruptive center. Within each segment, the location of the eruptive 
center is defined by a uniform distribution over the length of the segment. 
4. The Uniformly Spaced, Randomly Distributed, Correlated (USRD-C) approach. The 
distribution for the number of eruptive centers per volcanic event is derived from the 
PVHA experts interpretations. These distributions are completely correlated with the 
distributions for dike length. The total length of the dike is divided into equal 
segments for each eruptive center. Within each segment, the location of the eruptive 
center is defined by a uniform distribution over the length of the segment. 
5. The USRD-FD approach. The number of eruptive centers per volcanic event is 
determined by dividing the total length of the dike by an average distance between 
eruptive centers derived from the PVHA experts interpretations. The total length of 
the dike is divided into equal segments for each eruptive center. Within each segment, 
the location of the eruptive center is defined by a uniform distribution over the length 
of the segment. 
Application of the results of this report in assessing the impact of disruptive events will require a 
rule for combining the results for these five approaches. In the overall framework of the PVHA, 
this is accomplished by assigning weights to each model. These weights are derived by 
separately examining the three issues addressed by the alternative approaches. 
The first issue is the overall approach for evaluating the number of eruptive centers per volcanic 
event. The two approaches are to define a distribution for the total number based on the 
observed Quaternary data or to define the average spacing using the Quaternary data and 
compute the number for each dike length. These two approaches are considered to be equally 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 92 Septemb er 2003 
credible. They both rely to an equal degree on the observed data and the PVHA experts 
interpretations of these data to define the characteristics of volcanic events in the YMR. Thus, 
the two approaches are given equal weight. 
The second issue is the appropriate spatial distribution for eruptive centers along the length of 
the dike or dike system. Two alternative approaches are used, one in which the location of each 
eruptive center is independent of the others (IUD) and one in which the eruptive centers are 
spaced out along the total length of the dike system (USRD). The simulations shown on 
Figure 14 indicate that the IUD spatial model often produces tight clustering of multiple eruptive 
centers. This is somewhat at odds with the limited observations for eruptive centers in the 
vicinity of Yucca Mountain. Therefore, the URSD model is strongly preferred over the IUD 
model by a ratio of 3:1, yielding weights of 0.75 for the USRD models and 0.25 for the IUD 
models. Note that this assessment applies to the cases where the number of eruptive centers is 
derived from the distributions shown on Figure 18. When the number of eruptive centers is 
derived from an average spacing, only the USRD model is applied because it is consistent with 
the basis for determining the number of eruptive centers. 
The third issue addresses the correlation between the distributions for number of eruptive centers 
per volcanic event shown on Figure 18 and the distributions for the length of the dike associated 
with a volcanic event developed by the PVHA experts. Two alternatives were used: the two 
distributions are uncorrelated and the two distributions are fully correlated. It is likely that there 
is some degree of correlation because longer total dike lengths would provide more opportunity 
for the formation of vents and presumably result from volcanic events with larger volumes. 
Thus, the fully correlated model is slightly favored (0.6) to the uncorrelated model (0.4). Again, 
this assessment applies only to the cases where the number of eruptive centers is derived from 
the distributions shown in Figure 18. Determining the number of eruptive centers for a volcanic 
event using the average spacing and the total length produces full correlation between length and 
number of eruptive centers. 
Combining these three sets of weights yields the following relative weighting of the five 
approaches for computing the conditional distribution fo r number of eruptive centers within the 
proposed repository footprint: 
  The weight for the IUD-UC approach is equal to 0.5 for the approach for number of 
centers times 0.25 for the spatial approach times 0.4 for uncorrelated number of eruptive 
centers and dike length distributions, yielding a weight of 0.05. 
  The weight for the IUD-C approach is equal to 0.5 for the approach for number of 
centers times 0.25 for the spatial approach times 0.6 for correlated number of eruptive 
centers and dike length distributions, yielding a weight of 0.075. 
  The weight for the USRD-UC approach is equal to 0.5 for the approach for number of 
centers times 0.75 for the spatial approach times 0.4 for uncorrelated number of eruptive 
centers and dike length distributions, yielding a weight of 0.15. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 93 Septemb er 2003 
  The weight for the USRD-C approach is equal to 0.5 for the approach for number of 
centers times 0.75 for the spatial approach times 0.6 for uncorrelated number of eruptive 
centers and dike length distributions, yielding a weight of 0.225. 
  The weight for the USRD-FD approach is 0.5 for the approach, with only the USRD 
spatial approach applying and the correlation issue not pertinent, yielding a weight of 
0.5. 
These weights are used to combine the results of consequence evaluations for the five alternative 
approaches of number of eruptive centers in downstream analyses. 
Modification to the Uniformly Spaced, Randomly Distributed Fixed Density ApproachIn 
the previous version of this scientific analysis report (CRWMS M&O 2000 [151551]) and 
continued in this current version, the expected value of the average spacing between eruptive 
centers listed in Table 14 is replaced by the empirical distribution for the average spacing 
between eruptive centers in applying the USRD-FD approach. Table 15 lists the empirical 
distribution for the average spacing of eruptive centers derived in Attachment III from the PVHA 
experts interpretations. Note that the means of these distributions are equal to the expected 
values listed in Table 14. Using the full distribution for the average spacing of eruptive centers, 
rather than its expected value, makes the calculation for the USRD-FD approach consistent with 
those for the IUD and USRD approaches, which use empirical distributions for the number of 
eruptive centers per volcanic event. As a result of using the full distribution, there is an increase 
in the total number of eruptive centers that may occur within the repository footprint. The 
minimum value of the average spacing of eruptive centers in the empirical dis tributions is 
0.46 km (the spacing between Little Cones NE and Little Cones SW). Using this average 
spacing and the maximum repository dimensions, the maximum possible number of eruptive 
centers within the proposed LA repository footprint is 13. 
Table 15. Empirical Distribution for Average Spacing Between Eruptive 
Centers Calculation Results (from Attachment III, 
Table III-13 of this document) 
PVHA Expert 
Empirical Distribution for Average Spacing 
between Eruptive Centers (km) 
Alex McBirney (AM) 0.46 (0.0272), 2.01 (0.0492 ), 2.45 (0.0253 ), 2.80 
(0.8859 ), 2.88 (0.0124) 
Bruce Crowe (BC) 0.46 (0.4031), 1.62 (0.0489), 2.45 (0.1874), 2.80 
(0.0914), 2.88 (0.2203), 5.35 (0.0489) 
George Thompson (GT) 0.46 (0.4720), 2.01 (0.1279), 2.45 (0.1839), 2.80 
(0.1705), 2.88 (0.0457) 
George Walker (GW) 0.46 (0.5916), 2.45 (0.1767), 2.80 (0.0800), 2.88 
(0.1517) 
Mel Kuntz (MK) 0.46 (0.0550), 2.01 (0.2100), 2.45 (0.2950), 2.80 
(0.4200), 2.88 (0.0200) 
Michael Sheridan (MS) 0.46 (0.0388), 2.01 (0.1330), 2.45 (0.3238), 2.80 
(0.4656), 2.88 (0.0388) 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 94 Septemb er 2003 
Table 15. Empirical Distribution for Average Spacing Between Eruptive 
Centers Calculation Results (from Attachment III, Table 
III-13 of this document) (Continued) 
PVHA Expert 
Empirical Distribution for Average Spacing 
between Eruptive Centers (km) 
Richard Carlson (RC) 0.46 (0.1186), 2.45 (0.3608), 2.80 (0.4020), 2.88 
(0.1186) 
Richard Fisher (RF) 0.46 (0.0842), 1.62 (0.0192), 2.45 (0.3383), 2.80 
(0.5199), 2.88 (0.0192), 5.35 (0.0192) 
Wendell Duffield (WD) 0.46 (0.6445), 2.45 (0.0322), 2.80 (0.0833), 2.88 
(0.1560), 4.09 (0.0840) 
William Hackett (WH) 0.46 (0.4078), 2.45 (0.1844), 2.80 (0.0851), 2.88 
(0.1844), 4.09 (0.1383) 
OUTPUT DATA. DTN: LA0009FP831811.004 [152659] 
NOTE: The values in ( ) are the empirical probability for the preceding value 
of average spacing. 
Incorporation of Potential Effect of Repository OpeningsThe approaches developed above 
for assessing the spatial distribution of eruptive centers along the length of the dike or dikes 
associated with a volcanic event assume that the presence of the repository drifts has no impact 
on the likelihood of an eruptive conduit forming within the repository footprint. Therefore, for 
the calculation in the previous version of this scientific analysis report (Revision 00 ICN 01) 
(CRWMS M&O 2000 [151551]) and continued in this current version (Revision 01), two 
approaches are used to address the effect of the repository openings. The first approach 
considers the repository openings to have no effect and uses the weighted combination of the 
five approaches described above to develop the conditional distributions for rEC = 0, 1, 2, 3,  
The second approach considers that the repository openings will induce at least one eruptive 
center. For this approach the distribution for rEC is derived from the results of the first approach 
by setting the conditional probability of rEC = 0 to zero and renormalizing the probabilities for 
rEC = 1, 2, 3,  to sum to unity. For example, if the first approach resulted in a distribution for 
rEC of {0 (0.4), 1 (0.3), 2 (0.2), 3 (0.1)}, then the second approach would result in the distribution 
for rEC of {1 (0.5), 2 (0.333), 3 (0.167)}. Because there has not been significant study of the 
issue and the PVHA experts were not elicited on this questio n, maximum uncertainty weights of 
0.5 are applied to these two approaches for assessing the effect of the repository openings. As a 
result, the composite distribution for rEC in the above example would be {0 (0.2), 1 (0.4), 
2 (0.267), 3 (0.133)}. 
6.5.3 Results 
6.5.3.1 Frequency of Intersection of the Proposed Repository Footprint by a Dike for the 
License Application Footprint 
Table 16 lists the mean annual frequency of intersection of the proposed repository footprint and 
percentiles of the distribution for the frequency of intersection computed by full enumeration and 
by simulation with Latin hypercube sampling for the LA footprint. The results are listed for each 
expert, indicated by the experts initials from Table 11, and for the composite distribution over 
all 10 experts, with equal weight assigned to the individual expert assessments. The results 
computed by full enumeration of the experts logic trees are indicated by the suffix-FEn in the 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 95 Septemb er 2003 
column headings (e.g., AM-FEn) and the results computed by simulation are indicated by the 
suffix-Sim in the column headings (e.g., AM-Sim). The percent difference in the frequency of 
intersection is also listed in the tables. The differences between the frequencies of intersection 
computed by full enumeration and by simulation are generally small, ranging from -25.7 percent 
to +20.5 percent, indicating that simulation with Latin hypercube sampling reliably represents 
the full distribution for frequency of intersection. 
Table 16. Frequency of Intersection for the License Application Footprint (Blocks 1, 2, 3, and 5) 
AM1-FEn2 AM-Sim2 
% 
difference3 BC-FEn BC-Sim 
% 
difference GT-FEn GT-Sim 
% 
difference 
Mean 0.696E-08 0.698E-08 0.2 0.136E-07 0.135E-07 -0.3 0.379E-07 0.374E-07 -1.3 
0.05 0.199E-08 0.212E-08 6.3 0.118E-08 0.118E-08 -4.9 0.123E-07 0.117E-07 -4.8 
0.1 0.245E-08 0.253E-08 3.0 0.195E-08 0.179E-08 -8.5 0.148E-07 0.149E-07 0.7 
0.15 0.282E-08 0.303E-08 7.5 0.251E-08 0.238E-08 -5.1 0.174E-07 0.172E-07 -0.9 
0.2 0.316E-08 0.318E-08 0.4 0.295E-08 0.278E-08 -5.8 0.204E-07 0.192E-07 -5.8 
0.3 0.363E-08 0.364E-08 0.2 0.398E-08 0.389E-08 -2.3 0.229E-07 0.226E-07 -1.2 
0.4 0.407E-08 0.402E-08 -1.3 0.550E-08 0.542E-08 -1.4 0.263E-07 0.265E-07 0.6 
0.5 0.457E-08 0.467E-08 2.1 0.832E-08 0.819E-08 -1.5 0.316E-07 0.322E-07 1.8 
0.6 0.549E-08 0.529E-08 -3.7 0.132E-07 0.136E-07 3.5 0.372E-07 0.387E-07 4.3 
0.7 0.676E-08 0.646E-08 -4.4 0.178E-07 0.176E-07 -1.2 0.447E-07 0.436E-07 -2.3 
0.8 0.851E-08 0.827E-08 -2.8 0.240E-07 0.240E-07 -0.2 0.525E-07 0.501E-07 -4.6 
0.85 0.102E-07 0.111E-07 8.6 0.263E-07 0.265E-07 0.6 0.617E-07 0.575E-07 -6.7 
0.9 0.141E-07 0.138E-07 -2.7 0.309E-07 0.307E-07 -0.8 0.676E-07 0.656E-07 -3.0 
0.95 0.209E-07 0.214E-07 2.4 0.417E-07 0.402E-07 -3.6 0.776E-07 0.756E-07 -2.6 
GW-FEn GW-Sim 
% 
difference MK-FEn MK-Sim 
% 
difference MS-FEn MS-Sim 
% 
difference 
Mean 0.675E-08 0.695E-08 3.1 0.123E-07 0.120E-07 -2.0 0.190E-07 0.186E-07 -1.7 
0.05 0.126E-08 0.121E-08 -3.9 0.437E-09 0.468E-09 7.3 0.324E-08 0.341E-08 5.3 
0.1 0.174E-08 0.180E-08 3.6 0.912E-09 0.103E-08 13.4 0.468E-08 0.436E-08 -6.8 
0.15 0.219E-08 0.216E-08 -1.5 0.174E-08 0.186E-08 7.0 0.589E-08 0.539E-08 -8.4 
0.2 0.257E-08 0.233E-08 -9.2 0.251E-08 0.247E-08 -1.8 0.708E-08 0.629E-08 -11.2 
0.3 0.331E-08 0.312E-08 -5.7 0.398E-08 0.390E-08 -2.1 0.977E-08 0.841E-08 -13.9 
0.4 0.407E-08 0.401E-08 -1.6 0.603E-08 0.576E-08 -4.4 0.126E-07 0.110E-07 -12.4 
0.5 0.501E-08 0.493E-08 -1.7 0.813E-08 0.791E-08 -2.7 0.155E-07 0.148E-07 -4.3 
0.6 0.631E-08 0.587E-08 -7.0 0.107E-07 0.106E-07 -0.9 0.195E-07 0.188E-07 -3.4 
0.7 0.794E-08 0.791E-08 -0.4 0.141E-07 0.139E-07 -1.7 0.234E-07 0.238E-07 1.4 
0.8 0.102E-07 0.104E-07 1.4 0.186E-07 0.186E-07 0.0 0.282E-07 0.286E-07 1.6 
0.85 0.120E-07 0.123E-07 2.2 0.219E-07 0.216E-07 -1.3 0.316E-07 0.318E-07 0.7 
0.9 0.138E-07 0.139E-07 0.4 0.275E-07 0.265E-07 -3.7 0.363E-07 0.366E-07 0.8 
0.95 0.174E-07 0.155E-07 -10.6 0.363E-07 0.357E-07 -1.7 0.447E-07 0.443E-07 -0.8 
RC-FEn RC-Sim 
% 
difference RF-FEn RF-Sim 
% 
difference WD-FEn WD-Sim 
% 
difference 
Mean 0.157E-07 0.151E-07 -3.7 0.199E-07 0.197E-07 -0.8 0.166E-08 0.200E-08 20.5 
0.05 0.123E-08 0.130E-08 5.8 0.437E-08 0.437E-08 0.1 0.138E-09 0.134E-09 -3.0 
0.1 0.191E-08 0.177E-08 -7.3 0.617E-08 0.573E-08 -7.0 0.204E-09 0.205E-09 0.3 
0.15 0.251E-08 0.237E-08 -5.8 0.759E-08 0.687E-08 -9.5 0.257E-09 0.256E-09 -0.4 
0.2 0.339E-08 0.310E-08 -8.4 0.891E-08 0.816E-08 -8.4 0.339E-09 0.352E-09 3.9 

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ANL-MGR-GS-000001 REV 01 96 Septemb er 2003 
Table 16. Frequency of Intersection for the License Application Footprint (Blocks 1, 2, 3, and 5) 
(Continued) 
RC-FEn RC-Sim 
% 
difference RF-FEn RF-Sim 
% 
difference WD-FEn WD-Sim 
% 
difference 
0.3 0.468E-08 0.439E-08 -6.1 0.112E-07 0.111E-07 -1.2 0.537E-09 0.539E-09 0.3 
0.4 0.741E-08 0.736E-08 -0.7 0.138E-07 0.141E-07 2.5 0.100E-08 0.743E-09 -25.7 
0.5 0.977E-08 0.992E-08 1.5 0.170E-07 0.173E-07 1.8 0.123E-08 0.124E-08 0.7 
0.6 0.129E-07 0.130E-07 0.5 0.200E-07 0.196E-07 -1.8 0.123E-08 0.124E-08 0.8 
0.7 0.174E-07 0.176E-07 1.2 0.234E-07 0.234E-07 -0.3 0.151E-08 0.153E-08 0.9 
0.8 0.229E-07 0.230E-07 0.4 0.282E-07 0.283E-07 0.3 0.263E-08 0.229E-08 -12.9 
0.85 0.309E-07 0.303E-07 -2.0 0.316E-07 0.321E-07 1.5 0.295E-08 0.293E-08 -0.7 
0.9 0.372E-07 0.348E-07 -6.4 0.363E-07 0.379E-07 4.4 0.380E-08 0.382E-08 0.4 
0.95 0.525E-07 0.437E-07 -16.7 0.457E-07 0.444E-07 -2.8 0.457E-08 0.535E-08 16.9 
WH-FEn WH-Sim % difference Composite4 Fen Composite4 Sim % difference 
Mean 0.353E-07 0.357E-07 0.9 0.169E-07 0.168E-07 -0.6 
0.05 0.692E-08 0.702E-08 1.5 0.741E-09 0.743E-09 0.2 
0.1 0.871E-08 0.874E-08 0.4 0.148E-08 0.149E-08 0.4 
0.15 0.102E-07 0.102E-07 -0.1 0.229E-08 0.227E-08 -1.1 
0.2 0.120E-07 0.120E-07 -0.5 0.302E-08 0.296E-08 -2.0 
0.3 0.170E-07 0.164E-07 -3.5 0.457E-08 0.449E-08 -1.8 
0.4 0.234E-07 0.233E-07 -0.6 0.692E-08 0.673E-08 -2.7 
0.5 0.295E-07 0.299E-07 1.3 0.100E-07 0.992E-08 -0.8 
0.6 0.355E-07 0.363E-07 2.2 0.145E-07 0.142E-07 -1.9 
0.7 0.437E-07 0.440E-07 0.8 0.204E-07 0.203E-07 -0.8 
0.8 0.537E-07 0.542E-07 0.9 0.269E-07 0.276E-07 2.6 
0.85 0.603E-07 0.607E-07 0.8 0.331E-07 0.330E-07 -0.5 
0.9 0.692E-07 0.696E-07 0.5 0.407E-07 0.410E-07 0.7 
0.95 0.871E-07 0.891E-07 2.3 0.550E-07 0.533E-07 -3.0 
Output data. DTN: LA0303BY831811.001 [163985] 
NOTES: 1 AM = Alex McBirney, BC = Bruce Crowe, GT = George Thompson, GW = George Walker, MK = Mel 
Kuntz, MS = Michael Sheridan, RC = Richard Carlson, RF = Richard Fisher, WD = Wendell Duffield, 
WH = William Hackett. 
2 FEn = results from full enumeration, Sim = results from simulations with Latin hypercube sampling. 
3 The percent difference is computed as (Sim - FEn)/FEn. It represents the percent difference between the 
frequency of intersection computed by full enumeration and by simulation. 
4 The composite distributions are computed giving equal weight to the individual experts distributions. 
The computed distribution for the annual frequency of intersection of the proposed repository 
footprint by a dike is shown in Figure 20 for the proposed LA repository footprint. Part (a) of 
Figure 20 shows the computed distributions for the frequency of intersection aggregated over all 
of the 10 PVHA experts interpretations together with the median and mean values obtained for 
each experts interpretation. Part (b) of Figure 20 compares the 5th to 95th percentile range for 
frequency of intersection obtained for each experts interpretation with that for the aggregate 
distributions. 
The computed mean annual frequency of intersection of the proposed repository footprint by a 
dike is 1.7  10-8 for the LA footprint as compared to 1.5  10-8 obtained in the PVHA (CRWMS 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 97 Septemb er 2003 
M&O 1996 [100116], p. 4-10). The computed 5th and 95th percentiles of the uncertainty 
distribution for frequency of intersection are 7.4  10-10 and 5.5  10-8, respectively, as compared 
to 5.4  10-10 and 4.9  10-8 obtained in the PVHA (CRWMS M&O 1996 [100116], p. 4-10). 
Output Data. DTN: LA0303BY831811.001 [163985] 
NOTE: (a) Aggregate distribution and median and means for individual PVHA expert interpretations. (b) 
Range for 5th to 95th percentiles for results from individual PVHA expert interpretations compared to 
range for aggregate distribution. Two-letter code indicates initials of experts from Table 11. 
Figure 20. Annual Frequency of Intersecting the Proposed License Application Repository Footprint 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 98 Septemb er 2003 
The composite uncertainty distributions for frequency of intersection that are the output of these 
calculations for the proposed LA footprint are located in the output file PVHA-4P.DST in 
DTN: LA0302BY831811.001 [162670]. The file consists of a title record, a record giving the 
number of points in the composite distribution, and n records containing the n discrete values of 
frequency of intersection, the associated probability mass, and the cumulative probability (CDF). 
6.5.3.2 Conditional Distributions for Intersection Length, Azimuth, and Number of 
Eruptive Centers Within the Proposed License Application Repository Footprint 
The Latin hypercube sampling process described in Section 6.5.2.2 was used to compute joint 
distributions for length and azimuth of dike intersection at the mean, 5th, and 95th frequencies of 
intersection. At each of these frequencies of intersection distributions for the number of eruptive 
centers within the proposed repository LA footprint conditional on the length and azimuth within 
the repository of the intersecting dike system were developed. The joint distributions are listed 
in three output files (DTN: LA0303BY831811.001 [163985]): file CCSM-LA.CMP provides 
the joint distribution for length and azimuth of dike intersection and conditional distributions for 
the number of eruptive centers corresponding to the mean frequency of intersection; file 
CC05-LA.CMP provides the joint distribution for length and azimuth of dike intersection and 
conditional distributions for the number of eruptive centers corresponding to the 5th-percentile 
frequency of intersection; and file CC95-LA.CMP provides the joint distribution for length and 
azimuth of dike intersection and conditional distributions for the number of eruptive centers 
corresponding to the 95th-percentile frequency of exceedance. Each file consists of a title record, 
a record giving the number of points in the joint distribution for dike intersection length and 
azimuth, and n records containing the n pairs of intersection length and azimuth (LI
m and fn) and 
the joint probability of an intersection having that length and azimuth within the proposed 
repository. Also listed for each LI
m and fn pair is the composite conditional distribution for the 
number of eruptive centers within the proposed repository given the pair LI
m and fn. 
Figures 21, 22, and 23 show the marginal distributions for intersection length, intersection 
azimuth, and number of eruptive centers for the LA footprint, respectively, computed from the 
joint distributions described above. These results are also summarized in Tables 17, 18, and 19. 
The marginal distributions are computed from the joint distributions using software routine 
MARGIN V1.1 (STN: 10271-1.1-00 [148563]) (Figure 2). The results indicate the degree to 
which the distributions for length and azimuth of intersecting dikes and the number of eruptive 
centers vary with frequency of intersection. For example, results listed in Table 17 indicated that 
similar marginal distributions for dike intersection length are obtained at the 5th, mean, and 95th 
frequencies of intersection. The marginal distributions for intersection azimuth obtained at the 
5th, mean, and 95th frequencies of intersection (Table 18) are also similar. 
Figure 23 shows the marginal distributions for the number of eruptive centers within the 
repository footprint obtained using the five alternative approaches for the number and spatial 
distribution of eruptive centers along the length of the dike system. The IUD-UC approach 
produces the lowest probability of one or more eruptive centers within the proposed repository, 
approximately 0.4, and the USRD-FD approach produces the highest probability, approximately 
0.6. The values plotted in Figure 23 are those computed using the five alternative approaches for 
evaluating the number and spatial distribution of eruptive centers under the assumption that the 
presence of the proposed repository opening has no effect on the location of eruptive centers. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 99 Septemb er 2003 
These distributions are listed in the second through sixth columns of Table 19 under the overall 
subheading of Random Location for the formulation of eruptive center spatial distribution. 
The seventh column of Table 19 shows the marginal distribution for the weighted average results 
of the five approaches using the weights described at the end of Section 6.5.2.2 and indic ated in 
the column headings. The eighth column of Table 19 shows the marginal distribution for 
number of eruptive centers within the proposed repository footprint under the assumption that 
the presence of the repository openings results in at least one eruptive center within the proposed 
repository footprint given an intersection. The last column of Table 19 lists the final composite 
marginal distribution, which represents an equally weighted average of the random location 
assumption and the renormalized random distributions with P(rEC = 0) = 0 (eighth column). 
Similar marginal distributions for the number of eruptive centers are obtained at the 5th, mean, 
and 95th frequencies of intersection. 
The results summarized in Tables 17, 18, and 19 indicated that the distributions for intersecting 
dike length, intersecting dike azimuth, and number of eruptive centers within the repository 
footprint show little variation between the 5th, mean, and 95th frequencies of intersection. 
Therefore, the results obtained for the mean frequency of intersection can be used to assess the 
consequences of intrusive and extrusive distribution for all frequencies of intersection. 
Output Data. DTN: LA0303BY831811.001 [163985] 
NOTE: These distributions are conditional on the occurrence on an intersection. 
Figure 21. Marginal Distributions for Dike Intersection Length, LI, for the 5th Percentile, Mean, and 95th 
Percentile Frequency of Intersection 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 100 Septemb er 2003 
Table 17. Marginal Distributions for Dike Intersection Length for the 5th Percentile, Mean, and 95th 
Percentile Frequency of Intersection of the Proposed License Application Footprint 
Probability Mass 
Dike Intersection 
Length 
(km) 
5th Percentile 
Frequency of 
Intersection 
Mean Frequency 
of Intersection 
95th Percentile 
Frequency of 
Intersection 
0.0-0.255 0.1288 0.1088 0.1051 
>0.255-0.505 0.1159 0.1048 0.1012 
>0.505-0.755 0.1114 0.1054 0.1047 
>0.755-1.005 0.1336 0.1128 0.1105 
>1.005-1.255 0.1208 0.1189 0.1137 
>1.255-1.505 0.0821 0.0909 0.0888 
>1.505-1.755 0.0583 0.0674 0.0679 
>1.755-2.005 0.0492 0.0553 0.0591 
>2.005-2.255 0.0382 0.0430 0.0433 
>2.255-2.505 0.0353 0.0421 0.0417 
>2.505-2.755 0.0296 0.0323 0.0324 
>2.755-3.005 0.0255 0.0318 0.0334 
>3.005-3.255 0.0219 0.0263 0.0285 
>3.255-3.505 0.0190 0.0226 0.0230 
>3.505-3.755 0.0104 0.0089 0.0106 
>3.755-4.005 0.0044 0.0055 0.0065 
>4.005-4.255 0.0028 0.0043 0.0046 
>4.255-4.505 0.0025 0.0050 0.0062 
>4.505-4.755 0.0036 0.0028 0.0066 
>4.755-5.005 0.0039 0.0033 0.0031 
>5.005-5.255 0.0016 0.0036 0.0044 
>5.255-5.505 0.0013 0.0042 0.0043 
>5.505-5.755 0.0001 0.0003 0.0003 
Output data. DTN: LA0307BY831811.001 [164713] 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 101 Septemb er 2003 
Output Data. DTN: LA0303BY831811.001 [163985] 
NOTE: These distributions are conditional on the occurrence on an intersection. 
Figure 22. Marginal Distributions for Dike Intersection Azimuth, f, for the 5th Percentile, Mean, and 95th 
Percentile Frequency of Intersection for the Proposed License Application Footprint 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 102 Septemb er 2003 
Table 18. Marginal Distribution for Intersecting Dike Azimuth for the 5th Percentile, Mean, and 95th 
Percentile Frequency of Intersection of the Proposed License Application Footprint 
Probability Mass 
Intersecting Dike 
Azimuth 
() 
5th percentile 
Frequency of 
Intersection 
Mean Frequency 
of Intersection 
95th percentile 
Frequency of 
Intersection 
>-2.5-12.5 0.0560 0.0861 0.1072 
>12.5-22.5 0.1240 0.1485 0.1636 
>22.5-32.5 0.2030 0.2717 0.2491 
>32.5-42.5 0.2015 0.2372 0.2060 
>42.5-52.5 0.1463 0.1146 0.0955 
>52.5-62.5 0.0841 0.0464 0.0402 
>62.5-72.5 0.0431 0.0157 0.0188 
>72.5-82.5 0.0209 0.0053 0.0099 
>82.5-92.5 0.0102 0.0023 0.0055 
>92.5-102.5 0.0043 0.0011 0.0031 
>102.5-112.5 0.0013 0.0005 0.0017 
>112.5-122.5 0.0005 0.0004 0.0009 
>122.5-132.5 0.0019 0.0011 0.0015 
>132.5-142.5 0.0072 0.0037 0.0049 
>142.5-152.5 0.0193 0.0100 0.0145 
>152.5-162.5 0.0327 0.0182 0.0280 
>162.5-172.5 0.0316 0.0230 0.0325 
>172.5-177.5 0.0121 0.0142 0.0170 
Output data. DTN: LA0307BY831811.001 [164713] 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 103 Septemb er 2003 
Output Data. DTN: LA0303BY831811.001 [163985] 
NOTE: IUD = independent; uniformly distributed; USRD = uniformly spaced; randomly distributed; UC = 
uncorrelated length and number of eruptive centers per volcanic event distributions; C = correlated 
length and number of eruptive centers per volcanic event distributions; FD = fixed density for number of 
eruptive centers per volcanic event. 
Figure 23. Marginal Distributions for the Number of Eruptive Centers Within the Proposed Repository 
Footprint, rEC, for the 5th Percentile, Mean, and 95th Percentile Frequency of Intersection 
5th Percentile Hazard 
0 
0.1 
0.2 
0.3 
0.4 
0.5 
0.6 
0.7 
0.8 
0 1 2 3 4 5 6 7 8 9 10 11 12 13 
Number of Eruptive Centers within Repository Footprint 
Probability 
IUD-UC 
USRD-UC 
IUD-C 
USRD-C 
USRD-FD 
Mean Hazard 
0 
0.1 
0.2 
0.3 
0.4 
0.5 
0.6 
0.7 
0.8 
0 1 2 3 4 5 6 7 8 9 10 11 12 13 
Number of Eruptive Centers within Repository Footprint 
Probability 
IUD-UC 
USRD-UC 
IUD-C 
USRD-C 
USRD-FD 
95th Percentile Hazard 
0 
0.1 
0.2 
0.3 
0.4 
0.5 
0.6 
0.7 
0.8 
0 1 2 3 4 5 6 7 8 9 10 11 12 13 
Number of Eruptive Centers within Repository Footprint 
Probability 
IUD-UC 
USRD-UC 
IUD-C 
USRD-C 
USRD-FD

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ANL-MGR-GS-000001 REV 01 104 Septemb er 2003 
Table 19. Marginal Distribution for Number of Eruptive Centers Within the Proposed Repository for the 
5th Percentile, Mean, and 95th Percentile Frequency of Intersection of the Proposed License 
Application Footprint 
Formulation for Eruptive Center Spatial Distribution 
Random Location 
(weight 0.5) 
Repository 
Induces 
Eruptive 
Center 
(weight 0.5) 
Number of 
Eruptive 
Centers with 
Proposed 
Repository 
r.EC 
Independent, 
Uniformly 
Distributed, 
Uncorrelated, 
IUD-UC 
(weight 0.05) 
Uniformly 
Spaced, 
Randomly 
Distributed, 
Uncorrelated, 
USRD-UC 
(weight 0.15) 
Independent, 
Uniformly 
Distributed, 
Correlated, 
IUD-C 
(weight 
0.075) 
Uniformly 
Spaced, 
Randomly 
Distributed, 
Correlated, 
USRD-C 
(weight 
0.225) 
Uniformly 
Spaced, 
Randomly 
Distributed, 
Fixed Density, 
USRD-FD 
(weight 0.5) 
Weighted 
Average 
For 
Random 
Location 
Renormalized 
such that 
P(rEC=0)=0 
Final 
Composite 
Marginal 
Probability 
5th Percentile Frequency of Intersection 
0 0.693 0.672 0.571 0.516 0.391 0.490 0 0.245 
1 0.232 0.264 0.328 0.419 0.369 0.355 0.738 0.546 
2 0.0489 0.0414 0.0775 0.0537 0.102 0.0775 0.140 0.109 
3 0.0108 0.0098 0.0171 0.0088 0.0495 0.0300 0.0539 0.0419 
4 0.00688 0.00566 0.00520 0.00159 0.0301 0.0170 0.0273 0.0222 
5 0.00903 0.00728 0.00105 0.00015 0.0186 0.0109 0.0157 0.0133 
6 0 0 0 0 0.0151 0.00755 0.00985 0.00870 
7 0 0 0 0 0.0120 0.00598 0.00762 0.00680 
8 0 0 0 0 0.00677 0.00339 0.00423 0.00381 
9 0 0 0 0 0.00227 0.00114 0.00134 0.00124 
10 0 0 0 0 0.00269 0.00135 0.00166 0.00151 
11 0 0 0 0 0.00078 0.00039 0.00044 0.00041 
12 0 0 0 0 0.00033 0.00016 0.00018 0.00017 
13 0 0 0 0 0.00005 0.00002 0.00003 0.00002 
Mean Frequency of Intersection 
0 0.590 0.568 0.521 0.477 0.348 0.435 0 0.218 
1 0.312 0.347 0.383 0.454 0.390 0.394 0.740 0.567 
2 0.0661 0.0576 0.0756 0.0585 0.104 0.0829 0.134 0.108 
3 0.0140 0.0129 0.0148 0.0085 0.0540 0.0327 0.0533 0.0430 
4 0.00746 0.00616 0.00477 0.00137 0.0349 0.0194 0.0282 0.0238 
5 0.0103 0.00833 0.00097 0.00012 0.0240 0.0139 0.0187 0.0163 
6 0 0 0 0 0.0181 0.00903 0.0111 0.0101 
7 0 0 0 0 0.01271 0.00636 0.00763 0.00699 
8 0 0 0 0 0.00617 0.00308 0.00362 0.00335 
9 0 0 0 0 0.00269 0.00135 0.00154 0.00144 
10 0 0 0 0 0.00171 0.00086 0.00098 0.00092 
11 0 0 0 0 0.00149 0.00075 0.00086 0.00080 
12 0 0 0 0 0.00084 0.00042 0.00049 0.00045 
13 0 0 0 0 0.00010 0.00005 0.00006 0.00005 
95th Percentile Frequency of Intersection 
0 0.576 0.551 0.511 0.464 0.393 0.451 0 0.225 
1 0.316 0.355 0.385 0.459 0.410 0.406 0.789 0.597 
2 0.0699 0.0628 0.0795 0.0648 0.087 0.0768 0.118 0.0972 
3 0.0169 0.0155 0.0177 0.0102 0.0362 0.0249 0.0393 0.0321 
4 0.00948 0.00765 0.00591 0.00188 0.0242 0.0146 0.0209 0.0177 

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ANL-MGR-GS-000001 REV 01 105 Septemb er 2003 
Table 19. Marginal Distribution for Number of Eruptive Centers Within the Proposed Repository for the 
5th Percentile, Mean, and 95th Percentile Frequency of Intersection of the Proposed License 
Application Footprint (Continued) 
Formulation for Eruptive Center Spatial Distribution 
Random Location 
(weight 0.5) 
Repository 
Induces 
Eruptive 
Center 
(weight 0.5) 
Number of 
Eruptive 
Centers with 
Proposed 
Repository 
r.EC 
Independent, 
Uniformly 
Distributed, 
Uncorrelated, 
IUD-UC 
(weight 0.05) 
Uniformly 
Spaced, 
Randomly 
Distributed, 
Uncorrelated, 
USRD-UC 
(weight 0.15) 
Independent, 
Uniformly 
Distributed, 
Correlated, 
IUD-C 
(weight 
0.075) 
Uniformly 
Spaced, 
Randomly 
Distributed, 
Correlated, 
USRD-C 
(weight 
0.225) 
Uniformly 
Spaced, 
Randomly 
Distributed, 
Fixed Density, 
USRD-FD 
(weight 0.5) 
Weighted 
Average 
For 
Random 
Location 
Renormalized 
such that 
P(rEC=0)=0 
Final 
Composite 
Marginal 
Probability 
5 0.0114 0.00893 0.00126 0.00017 0.0167 0.0104 0.0142 0.0123 
6 0 0 0 0 0.0126 0.00629 0.00764 0.00696 
7 0 0 0 0 0.00940 0.00470 0.00558 0.00514 
8 0 0 0 0 0.00469 0.00234 0.00271 0.00253 
9 0 0 0 0 0.00225 0.00113 0.00126 0.00119 
10 0 0 0 0 0.00173 0.00086 0.00098 0.00092 
11 0 0 0 0 0.00145 0.00073 0.00082 0.00077 
12 0 0 0 0 0.00079 0.00040 0.00045 0.00042 
13 0 0 0 0 0.00007 0.00003 0.00004 0.00004 
Output data. DTN: LA0307BY831811.001 [164713] 
NOTE: Results presented in this table were rounded to at most three significant digits after calculation. 
6.5.4 Impact of 1999 Aeromagnetic Data on Frequency of Intersection 
Anomalies observed in aeromagnetic and ground magnetic data gathered by the USGS and the 
CNWRA, respectively, since completion of the PVHA suggest the possibility that a number of 
basaltic volcanic centers are buried beneath alluvium in Crater Flat and the northern Amargosa 
Desert (Blakely et al. 2000 [151881]; OLeary et al. 2002 [158468]; Hill and Stamatakos 2002 
[159500]). Interpretation of these data indicates that 20 to 24 magnetic anomalies occur within 
Crater Flat and the northern Amargosa Desert that could represent buried basaltic volcanoes 
(OLeary et al. 2002 [158468]; Hill and Stamatakos 2002 [159500]). Of these anomalies, eight 
were known at the time of the PVHA from previous surveys and were considered as possible 
volcanic events as part of the PVHA (Figure 24). 

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ANL-MGR-GS-000001 REV 01 106 Septemb er 2003 
Source: Magnetic Anomaly designations are from Hill and Stamatakos 2002. [159500]; (Coordinates from Hill 
and Stamatakos 2002 [159500]) 
NOTE: MC = Makani Cone; BC = Black Cone; RC = Red Cone; LC = Little Cones; LW = Lathrop Wells. PCF = 
Pliocene Crater Flat. 
Figure 24. Locations of Potential Buried Basalt Inferred from Aeromagnetic Data 
This section summarizes the methodology and results of an evaluation carried out as part of this 
report to determine the effect of the possible presence of buried volcanic centers on the results of 
the PVHA. The results of the evaluation are considered non-Q because the input data 
(OLeary et al. 2002 [158468]; Hill and Stamatakos 2002 [159500]) were not obtained using 
Yucca Mountain Project quality procedures. The results are for information only and are not to 
be used for purposes of assessing repository performance. 

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ANL-MGR-GS-000001 REV 01 107 Septemb er 2003 
Evaluation of the effect on the probability estimate from potential buried volcanic centers 
requires an estimate of the age of possible buried centers and an assessment of the likelihood that 
anomalies or groups of anomalies represent buried basaltic volcanic centers. 
The probable age range of potential buried volcanic centers was estimated by using a range of 
calculated sedimentation rates in Crater Flat and the Amargosa Valley and the modeled depth of 
anomalies from OLeary et al. 2002 [158468]. For two cases, the basalt in Crater Flat 
encountered in drill hole VH-2 and the basalt of Anomaly B, sedimentation rates were calculated 
by dividing the known depth (from drilling) of the buried basalt by the measured age of the 
basalt. These calculations give sedimentation rates of 0.03 and 0.04 mm/yr, respectively. 
A third case, Little Cones, has buried flows that have been characterized by ground magnetic 
surveys (Stamatakos et al. 1997 [138819]). Using a modeled depth to the top of the flows of 
15 m, a flow thickness of 10 m, and an age of 0.77-0.98 m.y. (Stamatakos et al. 1997 [138819], 
p. 328), the calculated sedimentation rate is 0.025-0.32 mm/yr. 
Using the range of calculated sedimentation rates discussed above and the modeled burial depth 
of anomalies (OLeary et al. 2002 [158468]), minimum and maximum ages were estimated for 
individual anomalies. Maximum ages for anomalies range from 2.5 to 8.3 m.y., and minimum 
ages range from 1.25 to 6.25 m.y. The exception to this age range is Anomaly T, which was 
estimated to be approximately 11 m.y. in age. Consideration of magnetic polarity data adds 
another age constraint, and a most likely age was chosen for each anomaly within the age 
range estimated for that anomaly. This approach leads to most likely ages for the anomalies that 
range from 2.6 to 6.3 m.y. All age ranges represent minimum ages (and, thus, are conservative 
for the purposes of volcanic hazard analysis) because they do not account for the thickness of the 
basalt bodies in calculating the depth of sediments deposited after basalt was emplaced. 
The PVHA experts made evaluations of the likelihood that the magnetic anomalies identified at 
that time represented buried volcanic centers. An individual experts confidence that an anomaly 
represented buried basalt generally depended on the experts interpretation of the shape, 
magnetic signature, and geologic setting of the anomaly (CRWMS M&O 1996 [100116]). 
OLeary et al. (2002 [158468]) and Hill and Stamatakos (2002 [159500]) used similar criteria to 
rank their confidence that the 20 to 24 anomalies identified in their reports represent buried 
basalt using a scale of one to four (OLeary et al. 2002 [158468]) and high, medium, and low 
(Hill and Stamatakos 2002 [159500]). Qualitatively, the rankings used in these two reports lead 
to similar conclusions regarding scientific confidence that particular anomalies represent buried 
basalt. The number of magnetic anomalies identified in these reports that may represent buried 
basalt depends upon the resolution of the aeromagnetic data. Hill and Stamatokos 
(2002 [159500]) suggest that basaltic features with areas smaller than 1 km2 are generally 
undetectable using the data presented in OLeary et al. (2002 [158468]). 
The potential impact of the aeromagnetic and ground magnetic data on the probability of igneous 
disruption of the proposed repository was assessed by developing distributions for the number of 
volcanic events represented by the anomalies, assigning these events to the volcanic sources 
defined by the experts in the 1996 PVHA, and calculating the annual frequency of intersection of 
the proposed repository footprint. The distributions for the number of volcanic events were 
developed using the tendency of each expert to group, or not group, aligned anomalies into 
single or multiple volcanic events. Two cases were developed. In the 1996 PVHA, the experts 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 108 Septemb er 2003 
did not consider all of the anomalies identified at that time to be buried volcanic centers. 
Instead, to varying degrees, they factored the likelihood that the anomalies represented buried 
volcanic centers into their assessments of the number of volcanic events that have occurred. 
Case 1 for this study was developed to be consistent with this approach. The distributions for the 
number of volcanic events represented by the magnetic anomalies for Case 1 were developed by 
the authors of this scientific analysis report using the qualitative likelihood that the anomalies 
represent buried volcanic centers discussed above and using each experts tendency for including 
anomalies with various levels of confidence into those experts distributions for volcanic events. 
In Case 2, all anomalies were assumed to be buried volcanic centers, and the distributions for the 
number of volcanic events were developed by the authors of this report based only on each 
experts tendency for grouping aligned volcanic centers into events. 
The PVHA experts considered the time period of interest for computing the rate of volcanic 
events in the YMR to range from the past 1 m.y. to the past 10 m.y., with the most likely time 
period to be the past 4.5 to 5 m.y. With the exception of Anomaly T, the age estimates for the 
anomalies generally fall within the past 6 m.y. For purposes of these sensitivity analyses, it was 
assumed that the ages of 22 anomalies (A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, 1, 2, 
3, and 4) fall within the past 4.5- to 5-m.y. time period. The age of Anomaly T was assumed to 
fall within the past 9- to 10-m.y. time period. Two of the PVHA experts considered a time 
period of the past 2 m.y. The range in age estimates for Anomalies O, 1, and 2 overlaps the 
2-m.y. time period, and, for these sensitivity analyses, these anomalies were given a 50 percent 
probability of being less than 2 m.y. in age. 
Table 20 lists the results of the sensitivity analyses in terms of the mean number of vo lcanic 
events occurring within the time period used by the experts to define the rate of volcanic events. 
For those experts who considered a 5-m.y. time period, the sensitivity analyses indicate an 
approximate 50 percent increase in the mean number of events for Case 1 (which incorporates 
the likelihood that the anomalies represent buried volcanic centers) and an approximate 
100 percent increase in the mean number of events for Case 2 (which assumes that all of the 
anomalies represent buried volcanic centers). 

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ANL-MGR-GS-000001 REV 01 109 Septemb er 2003 
Table 20. Comparison of Mean Number of Volcanic Events for 1996 Probabilistic Volcanic 
Hazard Analysis Assessment with Sensitivity Analysis Values 
Time Period 
Quaternary Plio-Quaternary 
Experta 1996 Case 1b Case 2b 1996 Case 1b Case 2b 
AM - - - 14.5 21.8 27.2 
BC - - - 16.7 24.0 29.7 
GT - - - 14.5 22.3 29.0 
GW - - - 14.8 22.8 30.6 
MK 4.1 4.6 5.6 11.1 17.9 25.6 
MS - - - 14.4 24.5 25.6 
RC - - - 12.0 18.5 24.4 
RF 4.4 5.1 5.9 - - - 
WD 6.6 6.6 6.6 - - - 
WH - - - 15.7 18.4 30.4 
Average 5.0 5.4 6.0 14.2 21.3 27.8 
N/A  For Reference Only 
NOTES a AM = Alexander McBirney; BC = Bruce Crowe; GT = George Thompson; GW = George 
Walker; MK = Mel Kuntz; MS = Michael Sheridan; RC = Richard Carlson; RF = Richard 
Fisher; WD = Wandell Duffield; WH = William Hackett. 
b Case 1 and Case 2 were developed by the authors of this report based on the 1996 
PVHA experts preferences for grouping aligned volcanic centers into volcanic events. 
For the two experts who considered a 2-m.y. time period, the sensitivity analyses result in 
increases of 10 and 20 percent for Case 1 and Case 2, respectively. Duffield considered only a 
1-m.y. time period but assigned low probabilities that some of the anomalies are less than 1 m.y. 
in age (CRWMS M&O 1996 [100116]). Applying this assessment to the larger population of 
anomalies results in less than a 1-percent increase in the mean number of volcanic events. 
For each expert in this sensitivity study, the distributions for the number of volcanic events 
developed were assigned to the appropriate volcanic sources defined by the PVHA experts. In 
general, the magnetic anomalies lie within or slightly to the west of the experts Crater Flat and 
Amargosa Valley sources. Therefore, for these sensitivity analyses, the volcanic events 
represented by the magnetic anomalies were assigned to the experts Crater Flat and Amargosa 
Valley sources (i.e., source zones, Gaussian fields, kernel density functions) rather than to larger 
background source zones. 
Figures 25 and 26 show the results of the sensitivity analyses in terms of the computed 
distributions for the frequency of intersection of the proposed repository footprint by a basaltic 
dike. The footprint used for these analyses is the 70,000-MTU no-backfill repository layout 
(primary-plus-contingency blocks) used in the previous version (Revision 00 ICN 01) of this 
report (CRWMS M&O 2000 [151551]). Use of this footprint results in approximately 6 percent 
lower frequencies of intersections than if the proposed LA footprint had been used to assess the 
impact (based on comparison of the mean annual frequency of intersection from the two 
footprints). The results are summarized in Table 21. The volcanic event count distributions 
developed for sensitivity Case 1 result in a 22-percent increase in the mean annual frequency of 
intersection, and those for sensitivity Case 2 result in a 40-percent increase. The increase in the 
frequency of intersection is less than the increase in the mean number of volcanic events because 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 110 Septemb er 2003 
the additional events are located in the more active volcanic sources to the west of the site. As 
indicated in Figure 17, a significant portion of the volcanic hazard results from the occurrence of 
volcanic events near or to the northeast of the proposed repository, areas in which the estimated 
rate of volcanic events is not greatly affected by inclusion of the additional magnetic anomalies 
in the volcanic event count distributions. 
Table 21. Summary of Computed Frequency of Intersection for 70,000-Metric Tons of Uranium 
No-Backfill Repository Layout (primary + contingency blocks) from Sensitivity Cases 
Annual Frequency of Intersection 
Input Parameters 5th percentile 50th percentile Mean 95th percentile 
1996 PVHA 7.9E-10 9.8E-09 1.6E-08 5.2E-08 
Sensitivity Case 1 7.8E-10 1.0E-08 1.9E-08 6.5E-08 
Sensitivity Case 2 7.9E-10 1.1E-08 2.2E-08 7.6E-08 
NOTE: N/A - Reference only 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 111 Septemb er 2003 
N/A -For Reference Only 
NOTE: Results labeled 1996 use the PVHA volcanic event counts; results labeled Case 1 and Case 2 use the 
volcanic event counts developed in this sensitivity analysis. 
Figure 25. Composite Annual Frequency of Intersection of the Repository Footprint for Sensitivity Cases 
for the Primary-plus-Contingency Block Case of the 70,000-Metric Tons of Uranium 
No-Backfill Layout 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 112 Septemb er 2003 
N/A  For Reference Only 
NOTE: Results labeled 1996 use the PVHA volcanic event counts; results labeled Case 1 and Case 2 use the 
volcanic event counts developed for the sensitivity cases. 
Figure 26. Individual Expert Results for Annual Frequency of Intersection of the Proposed Repository 
Footprint for Sensitivity Cases for the Primary-plus-Contingency Block Case of the 
70,000-Metric Tons of Uranium No-Backfill Layout 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 113 Septemb er 2003 
7. CONCLUSIONS 
7.1 SUMMARY OF SCIENTIFIC ANALYSIS 
The result of the PVHA (CRWMS M&O 1996 [100116]) has been recalculated using PVHA 
outputs to account for the proposed LA repository footprint (the outline of the waste 
emplacement area) and extended to include the probability of an eruption within the proposed 
LA repository footprint, conditio nal on a dike intersection (Table 22). A conceptual framework 
for the probability calculations, based on PVHA outputs and subsequent studies, accounts for 
deep (mantle) and shallow (structural control) processes that influence volcanic event 
distribution and recurrence rate in the YMR. The framework presented here emphasizes the 
close correlation between the distribution of volcanic events and areas of crustal extension and 
faulting in the YMR, and within this context, the appropriateness of volcanic source zone 
boundaries defined in the PVHA. It also emphasizes the appropriate selection of parameter 
distributions that affect probability models and provides support for comparison of alternative 
scenarios and parameter selection, within the framework of the volcanic history of the YMR. 
Alternative models presented by Connor et al. (2000 [149935]) that result in higher eruption 
probabilities (10-7 versus 1.310-8 per year) than those presented here are found to employ input 
parameters that either represent extreme values (e.g., event length) or assume a specific geologic 
control (i.e., crustal density) on spatial distribution while not considering more defensible and 
observable controls (i.e., crustal extension and structure). Spatial density models weighted by 
crustal density result in higher event frequencies at the proposed repository site, while the same 
models weighted by an alternative geologic control such as cumulative crustal extension across 
the Crater Flat structural domain would likely lead to decreased event frequencies at the site. 
Connor et al. (2000 [149935]) state that the highest value (10-7 per year) in their range of 
calculated probability values (10-810-7 per year) cannot be considered more or less likely than 
any other value they have calculated using alternative probability models. The analysis in this 
report suggests that the choice of input parameters used by Connor et al. (2000 [149935]) 
compared to those used in the PVHA logically places their highest probability value at the 
extreme upper tail of a probability distribution. 
The annual frequency of intersection of the proposed repository footprint by a dike or dike 
system associated with a volcanic event and the annual frequency of a volcanic event producing 
one or more eruptive centers within the proposed repository have been recalculated, based on the 
current proposed repository footprint. These results are summarized in Table 22. The annual 
frequency of disruption of the repository by one or more eruptive centers is obtained by 
multiplying the frequency of intersection from Figure 20 by the conditional probability of the 
occurrence of at least one eruptive center (1 minus the conditional probability of 0 centers) from 
the right-hand column of Table 19. It is important to note that the reported values represent the 
annual frequencies of intrusive and extrusive disruption of the repository waste emplacement 
footprint by a volcanic event includes the possibility for multiple parallel dikes (see definition of 
volcanic event at the beginning of Section 6.5). For assessing the consequences of igneous 
intrusion, users of the results of this scientific analysis must consider the distribution for the 
number of parallel dikes associated with a volcanic event. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 114 Septemb er 2003 
Conditional distributions for the length and azimuth of the intersecting dike and the number of 
eruptive centers occurring within the proposed repository footprint are developed for the three 
values of frequency of intersection in Table 22. These distributions are very similar for the three 
levels of frequency of intersection. Because of this similarity, it is appropriate to use the 
conditional distributions obtained for the mean frequency of intersection to perform consequence 
analyses and as input to TSPA, as described below in Section 7.2. 
The inputs to this scientific analysis report are the results of an expert elicitation conducted in a 
manner consistent with the guidance in the Branch Technical Position on Expert Elicitation 
(Kotra et al. 1996 [100909]). The PVHA experts explicitly quantified the uncertainties in their 
interpretations and they are represented in the outputs of this report in the form of probability 
distributions. Thus, it is concluded that the results of this report form an appropriate basis for the 
evaluation of the consequences of volcanic hazards in the YMR. YMRP (NRC 2003 [163274]) 
acceptance criteria have been met as described in Attachment I of this report. 
Table 22. Summary Frequencies of Disruptive Volcanic Events for the License Application Footprint 
Annual Frequency of 
Intersection of Proposed 
Repository by a Volcanic 
Event 
Composite Conditional 
Probability of at Least 
One Eruptive Center 
Annual Frequency of 
Occurrence of One or 
More Eruptive Centers 
within Proposed 
Repository 
7.410-10 (5th percentile) 0.75 5.610-10 
1.710-8 (mean) 0.78 1.310-8 
5.510-8 (95th percentile) 0.77 4.310-8 
DTN: LA0307BY831811.001 [164713] (Output data) 
NOTE: Results presented in this table were rounded to two significant digits after 
calculation. 
7.2 OUTPUTS BASED ON THE PROPOSED LICENSE APPLICATION FOOTPRINT 
(BLOCKS 1, 2, 3, AND 5) 
The outputs of this scientific analysis report based on the proposed LA Footprint are described in 
detail in Section 6.5.3. They are summarized as the following. 
1. A discrete probability distribution for the annual frequency of intersection of the 
proposed repository emplacement area footprint by a dike or dike system. This 
distribution is given in output file PVHA-4PA.DST (DTN: LA0307BY831811.001 
[164713]). The file contains three columns of data. The first column contains discrete 
values for the annual frequency of intersection. The second column contains the 
probability mass associated with each frequency of intersection. The third column 
contains the cumulative probability that the frequency of intersection is equal to or 
lower than the corresponding value in the third first. 
2. A discrete probability distribution for the annual frequency of disruption of the 
proposed repository emplacement area footprint by one or more eruptive centers. This 
distribution is obtained by multiplying the first column of output file PVHA-4PA.DST 
(DTN: LA0302BY831811.001 [162670]) by 0.782, the conditional probability of 
disruption by at least one eruptive center, given intersection of the repository. As 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 115 Septemb er 2003 
discussed in Sections 6.5.3.2 and 7.1, it is considered appropriate to use the 
conditional probability obtained for the mean frequency of intersection to define the 
full distribution for frequency of extrusive disruption. 
3. Conditional joint probability distributions for length and azimuth of an intersecting 
dike, and number of eruptive centers within the proposed repository LA 
footprint, output files CCSM-LA.CMP, CC05-LA.CMP, and CC95-LA.CMP 
(DTN: LA0302BY831811.001 [162670]). As discussed in Sections 6.5.3.2 and 7.1, it 
is considered appropriate to use the distributions obtained for the mean frequency of 
intersection (output file CCSM-LA.CMP) to evaluate consequences at all frequencies 
of intersection. 
Because the proposed LA footprint is the current proposed repository design, the outputs from 
the calculations based on this particular repository layout and presented in this report will be 
used as input to revisions of the Number of Waste Packages Hit by Igneous Intrusion report 
(BSC 2003 [161851]) and as inputs to TSPA-LA. 
7.3 UNCERTAINTIES 
The data and parameter inputs to the PVHA, as well as their uncertainty, were defined as part of 
the expert elicitation process. All of the uncertainties defined by the elicitation process were 
fully propagated through the probability models and are reflected in the final probability 
distribution. Selection of particular parameter values, ranges, and bounding assumptions for 
conceptual models were arrived at through the process of expert elicitation. The contributions to 
uncertainty from each of the PVHA components are described in CRWMS M&O (1996 
[100116], Section 4.2) and Section 6.3.1.5 of this scientific analysis report. 
8. INPUTS AND REFERENCES 
8.1 DOCUMENTS CITED 
The following is a list of the references cited in this document. Column 1 represents the unique 
six-digit numerical identifier (the Document Input Reference System [DIRS] number), which is 
placed in the text following the reference callout (e.g., BSC 2002 [155950]). The purpose of 
these numbers is to assist the reader in locating a specific reference in the DIRS database. 
Within the reference list, multiple sources by the same author and date (e.g., BSC 2002) are 
alphabetically by title. 
160533 AP-SV.1Q, Rev. 0, ICN 3. Control of the Electronic Management of Information. 
Washington, D.C.: U.S. Department of Energy, Office of Civilian Radioactive Waste 
Management. ACC: MOL.20020917.0133. 
151881 Blakely, R.J.; Langenheim, V.E.; Ponce, D.A.; and Dixon, G.L. 2000. Aeromagnetic 
Survey of the Amargosa Desert, Nevada and California: A Tool for Understanding 
Near-Surface Geology and Hydrology. Open-File Report 00-188. Denver, Colorado: 
U.S. Geological Survey. TIC: 248767. 

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ANL-MGR-GS-000001 REV 01 116 Septemb er 2003 
100022 Brocher, T.M.; Hunter, W.C.; and Langenheim, V.E. 1998. Implications of Seismic 
Reflection and Potential Field Geophysical Data on the Structural Framework of the 
Yucca Mountain-Crater Flat Region, Nevada. Geological Society of America 
Bulletin, 110 (8), 947-971. Boulder, Colorado: Geological Society of America. 
TIC: 238643. 
147772 Brocoum, S.J. 1997. Evaluation of Data Provided at U.S. Department of Energy 
(DOE) and U.S. Nuclear Regulatory Commission (NRC) Igneous Activity Technical 
Exchange, February 25-26, 1997. Letter from S.J. Brocoum (DOE/OCRWM) to 
J.T. Greeves (NRC), June 4, 1997, with enclosure. ACC: MOL.19970722.0276; 
MOL.19970722.0277. 
160313 BSC (Bechtel SAIC Company) 2002. Scientific Processes Guidelines Manual. 
MIS-WIS-MD-000001 REV 01. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: MOL.20020923.0176. 
159527 BSC 2002. Repository Design, Repository/PA IED Subsurface Facilities Plan Sht. 
1 of 5, Sht. 2. of 5, Sht. 3 of 5, Sht. 4 of 5, and Sht. 5 of 5. DWG-MGR-MD-000003 
REV A. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: MOL.20020601.0194. 
158966 BSC 2002. The Enhanced Plan for Features, Events, and Processes (FEPs) at Yucca 
Mountain. TDR-WIS-PA-000005 REV 00. Las Vegas, Nevada: Bechtel SAIC 
Company. ACC: MOL.20020417.0385. 
161315 BSC 2002. Technical Work Plan for: Igneous Activity Analysis for Disruptive 
Events. TWP-WIS-MD-000007 REV 02. Las Vegas, Nevada: Bechtel SAIC 
Company. ACC: MOL.20030107.0009. 
161838 BSC 2003. Characterize Eruptive Processes at Yucca Mountain, Nevada. 
ANL-MGR-GS-000002 REV 01. Las Vegas, Nevada: Bechtel SAIC Company. 
161851 BSC 2003. Number of Waste Packages Hit by Igneous Intrusion. ANL-MGR-GS- 
000003 REV 00. Las Vegas, Nevada: Bechtel SAIC Company. 
162289 BSC (Bechtel SAIC Company) 2003. Repository Design, Repository/PA IED 
Subsurface Facilities. 800-IED-EBS0-00401-000-00C. Las Vegas, Nevada: Bechtel 
SAIC Company. ACC: ENG.20030303.0002. 
101859 Byers, F.M., Jr. and Barnes, H. 1967. Geologic Map of the Paiute Ridge 
Quadrangle, Nye and Lincoln Counties, Nevada. Map GQ-577. Washington, D.C.: 
U.S. Geological Survey. ACC: HQS.19880517.1104. 
161770 Canori, G.F. and Leitner, M.M. 2003. Project Requirements Document. TER-MGRMD-
000001 REV 01. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: DOC.20030404.0003. 

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ANL-MGR-GS-000001 REV 01 117 Septemb er 2003 
102646 Connor, C.B. and Hill, B.E. 1995. Three Nonhomogeneous Poisson Models for the 
Probability of Basaltic Volcanism: Application to the Yucca Mountain Region, 
Nevada. Journal of Geophysical Research, 100 (B6), 10,107-10,125. 
Washington, D.C.: American Geophysical Union. TIC: 237682. 
135969 Connor, C.B.; Stamatakos, J.; Ferrill, D.; Hill, B.E.; Magsino, S.B.L.; La Femina, P.; 
and Martin, R.H. 1997. Integrating Structural Models into Probabilistic Volcanic 
Hazard Analyses: An Example from Yucca Mountain, NV. Abstracts with 
Programs  Geological Society of America, 28, (7), A-192. Boulder, Colorado: 
Geological Society of America. TIC: 247409. 
149935 Connor, C.B.; Stamatakos, J.A.; Ferrill, D.A.; Hill, B.E.; Ofoegbu, G.I.; Conway, 
F.M.; Sagar, B.; and Trapp, J. 2000. Geologic Factors Controlling Patterns of 
Small-Volume Basaltic Volcanism: Application to a Volcanic Hazards Assessment at 
Yucca Mountain, Nevada. Journal of Geophysical Research, 105, (B1), 417432. 
Washington, D.C.: American Geophysical Union. TIC: 247906. 
100973 Crowe, B.M. and Perry, F.V. 1990. Volcanic Probability Calculations for the 
Yucca Mountain Site: Estimation of Volcanic Rates. Proceedings of the Topical 
Meeting on Nuclear Waste Isolation in the Unsaturated Zone, FOCUS 89, 
September 17-21, 1989, Las Vegas, Nevada. Pages 326-334. La Grange Park, 
Illinois: American Nuclear Society. TIC: 212738. 
102741 Crowe, B.M.; Johnson, M.E.; and Beckman, R.J. 1982. Calculation of the 
Probability of Volcanic Disruption of a High-Level Radioactive Waste Repository 
Within Southern Nevada, USA. Radioactive Waste Management and the Nuclear 
Fuel Cycle, 3 (2), 167190. New York, New York: Harwood Academic Publishers. 
TIC: 222179. 
100026 Crowe, B.M.; Perry, F.V.; Valentine, G.A.; Wallmann, P.C.; and Kossik, R. 1993. 
Simulation Modeling of the Probability of Magmatic Disruption of the Potential 
Yucca Mountain Site. Proceedings of the Topical Meeting on Site Characterization 
and Model Validation, Focus 93, September 26-29,1993. Pages 182-191. 
La Grange Park, Illinois: American Nuclear Society. TIC: 102245. 
100110 Crowe, B.; Perry, F.; Geissman, J.; McFadden, L.; Wells, S.; Murrell, M.; Poths, J.; 
Valentine, G.A.; Bowker, L.; and Finnegan, K. 1995. Status of Volcanism Studies 
for the Yucca Mountain Site Characterization Project. LA-12908-MS. Los Alamos, 
New Mexico: Los Alamos National Laboratory. ACC: HQO.19951115.0017. 
100116 CRWMS M&O (Civilian Radioactive Waste Management System Management and 
Operating Contractor). 1996. Probabilistic Volcanic Hazard Analysis for Yucca 
Mountain, Nevada. BA0000000-01717-2200-00082, Rev 0. Las Vegas, Nevada: 
CRWMS M&O. ACC: MOL.19971201.0221. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 118 Septemb er 2003 
106102 CRWMS M&O 1998. Disruptive Events. Chapter 10 of Total System 
Performance AssessmentViability Assessment (TSPA-VA) Analyses Technical Basis 
Document. B00000000-01717-4301-00010, REV 00. Las Vegas, Nevada: CRWMS 
M&O. ACC: MOL.19980724.0399. 
100129 CRWMS M&O 1998. Geochemistry. Book 3 - Sectio n 6 of Yucca Mountain Site 
Description. B00000000-01717-5700-00019 REV 00. Las Vegas, Nevada: 
CRWMS M&O. ACC: MOL.19980729.0052. 
105347 CRWMS M&O 1998. Synthesis of Volcanism Studies for the Yucca Mountain Site 
Characterization Project. Deliverable 3781MR1. Las Vegas, Nevada: CRWMS 
M&O. ACC: MOL.19990511.0400. 
151551 CRWMS M&O 2000. Characterize Framework for Igneous Activity at Yucca 
Mountain, Nevada. ANL-MGR-GS-000001 REV 00 ICN 01. Las Vegas, Nevada: 
CRWMS M&O. ACC: MOL.20001221.0001. 
151553 CRWMS M&O 2000. Features, Events, and Processes: Disruptive Events. 
ANL-WIS-MD-000005 REV 00 ICN 1. Las Vegas, Nevada: CRWMS M&O. 
ACC: MOL.20001218.0007. 
153246 CRWMS M&O 2000. Total System Performance Assessment for the Site 
Recommendation. TDR-WIS-PA-000001 REV 00 ICN 01. Las Vegas, Nevada: 
CRWMS M&O. ACC: MOL.20001220.0045. 
100027 Day, W.C.; Dickerson, R.P.; Potter, C.J.; Sweetkind, D.S.; San Juan, C.A.; Drake, 
R.M., II; and Fridrich, C.J. 1998. Bedrock Geologic Map of the Yucca Mountain 
Area, Nye County, Nevada. Geologic Investigations Series I-2627. 
Denver, Colorado: U.S. Geological Survey. ACC: MOL.19981014.0301. 
145370 Delaney, P.T. and Gartner, A.E. 1997. Physical Processes of Shallow Mafic Dike 
Emplacement Near the San Rafael Swell, Utah. Geological Society of America 
Bulletin, 109 (9), 11771192. Boulder, Colorado: Geological Society of America. 
TIC: 247421. 
100550 DOE (U.S. Department of Energy). 1998. Total System Performance Assessment. 
Volume 3 of Viability Assessment of a Repository at Yucca Mountain. DOE/RW- 
0508. Washington, D.C.: U.S. Department of Energy, Office of Civilian Radioactive 
Waste Management. ACC: MOL.19981007.0030. 
147778 Earthfield Technology. 1995. Summary Report: Magnetic and Gravity Study of the 
Yucca Mountain Area, Nevada. Houston, Texas: Earthfield Technology. 
ACC: MOL.20000228.0374. 
105284 Farmer, G.L.; Perry, F.V.; Semken, S.; Crowe, B.; Curtis, D.; and DePaolo, D.J. 
1989. Isotopic Evidence on the Structure and Origin of Subcontinental Lithospheric 
Mantle in Southern Nevada. Journal of Geophysical Research, 94, (B6), 7885-7898. 
Washington, D.C.: American Geophysical Union. TIC: 201800. 

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ANL-MGR-GS-000001 REV 01 119 Septemb er 2003 
105078 Feighner, M.A. and Majer, E.L. 1996. Results of the Analysis of the Timber Mt., 
Lathrop Wells, and Yucca Mt. Aeromagnetic Data. Milestone SPT23KM4. 
Berkeley, California: Lawrence Berkeley National Laboratory. 
ACC: MOL.19971204.0767. 
105315 Ferrill, D.A.; Stamatakos, J.A.; Jones, S.M.; Rahe, B.; McKague, H.L.; Martin, R.H.; 
and Morris, A.P. 1996. Quaternary Slip History of the Bare Mountain Fault 
(Nevada) from the Morphology and Distribution of Alluvial Fan Deposits. Geology, 
24, (6), 559562. Boulder, Colorado: Geological Society of America. TIC: 234557. 
154365 Freeze, G.A.; Brodsky, N.S.; and Swift, P.N. 2001. The Development of Information 
Catalogued in REV00 of the YMP FEP Database. TDR-WIS-MD-000003 REV 00 
ICN 01. Las Vegas, Nevada: Bechtel SAIC Company. 
ACC: MOL.20010301.0237. 
118942 Fridrich, C.J. 1999. Tectonic Evolution of the Crater Flat Basin, Yucca Mountain 
Region, Nevada. Chapter 7 of Cenozoic Basins of the Death Valley Region. Wright, 
L.A. and Troxel, B.W., eds. Special Paper 333. Boulder, Colorado: Geological 
Society of America. TIC: 248054. 
107333 Fridrich, C.J.; Whitney, J.W.; Hudson, M.R.; and Crowe, B.M. 1999. Space-Time 
Patterns of Late Cenozoic Extension, Vertical Axis Rotation, and Volcanism in the 
Crater Flat Basin, Southwest Nevada. Chapter 8 of Cenozoic Basins of the Death 
Valley Region. Wright, L.A., and Troxel, B.W., eds. Special Paper 333. 
pp. 197-212. Boulder, Colorado: Geological Society of America. TIC: 248054. 
107255 Heizler, M.T.; Perry, F.V.; Crowe, B.M.; Peters, L.; and Appelt, R. 1999. The Age 
of Lathrop Wells Volcanic Center: An 40Ar/39Ar Dating Investigation. Journal of 
Geophysical Research, 104 (B1), 767804. Washington, D.C.: American 
Geophysical Union. TIC: 243399. 
159500 Hill, B.E. and Stamatakos, J.A. 2002. Evaluation of Geophysical Information Used 
to Detect and Characterize Buried Volcanic Features in the Yucca Mountain Region. 
San Antonio, Texas: Center for Nuclear Waste Regulatory Analyses. TIC: 252846. 
140152 Ho, C.-H. and Smith, E.I. 1998. A Spatia l-Temporal/3-D Model for Volcanic 
Hazard Assessment: Application to the Yucca Mountain Region, Nevada. 
Mathematical Geology, 30 (5), 497510. New York, New York: Plenum Publishing 
Corporation. TIC: 245110. 
106194 Hudson, M.R.; Minor, S.A.; and Fridrich, C.J. 1996. The Distribution, Timing, and 
Character of Steep-Axis Rotations in a Broad Zone of Dextral Shear in Southwestern 
Nevada. Abstracts with Programs, 28, (7), A-451. Boulder, Colorado: Geological 
Society of America. TIC: 234723. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 120 Septemb er 2003 
100909 Kotra, J.P.; Lee, M.P.; Eisenberg, N.A.; and De Wispelare, A.R. 1996. Branch 
Technical Position on the Use of Expert Elicitation in the High-Level Radioactive 
Waste Program. NUREG-1563. Washington, D.C.: U.S. Nuclear Regulatory 
Commission. TIC: 226832. 
148622 Langenheim, V.E.; Kirchoff-Stein, K.S., and Oliver, H.W. 1993. Geophysical 
Investigations of Buried Volcanic Centers Near Yucca Mountain, Southwest 
Nevada. High-Level Radioactive Waste Management, Proceedings of the Fourth 
Annual International Conference, Las Vegas, Nevada, April 26-30, 1993. 2, 
1840-1846. La Grange Park, Illinois: American Nuclear Society. TIC: 208542. 
162310 Livaccari, R.F. and Perry, F.V. 1993. Isotopic Evidence for Preservation of 
Cordilleran Lithospheric Mantle During the Sevier-Laramide Orogeny, Western 
United States. Geology, 21, 719722. 
147781 Magsino, S.L.; Connor, C.B.; Hill, B.E.; Stamatakos, J.A.; La Femina, P.C.; Sims, 
D.A.; and Maratin, R.H. 1998. CNWRA Ground Magnetic Surveys in the Yucca 
Mountain Region, Nevada (1996-1997). CNWRA 98-001. San Antonio, Texas: 
Center for Nuclear Waste Regulatory Analyses. TIC: 247807. 
127905 McKay, M.D.; Beckman, R.J.; and Conover, W.J. 1979. A Comparison of Three 
Methods for Selecting Values of Input Variables in the Analysis of Output from a 
Computer Code. Technometrics, 21, (2), 239245. Alexandria, Virginia: American 
Statistical Association. TIC: 221741. 
163274 NRC (U.S. Nuclear Regulatory Commision) 2003. Yucca Mountain Review 
Plan,Final Report. NUREG-1804, Rev. 2. Washington, D.C.: U.S. Nuclear 
Regulatory Commision, Office of Nuclear Material Safety and Safeguards. 
TIC: 254568. 
158468 OLeary, D.W.; Mankinen, E.A.; Blakely, R.J.; Langenheim, V.E.; and Ponce, D.A. 
2002. Aeromagnetic Expression of Buried Basaltic Volcanoes Near Yucca Mountain, 
Nevada. Open-File Report 02-020. Denver, Colorado: U.S. Geological Survey. 
ACC: MOL.20020627.0225. 
159502 Perry, F.V. and Bowker, L.M. 1998. Petrologic and Geochemical Constraints on 
Basaltic Volcanism in the Great Basin. Chapter 4 of Volcanism Studies: Final 
Report for the Yucca Mountain Project. Perry, F.V.; Crowe, B.M.; Valentine, G.A.; 
and Bowker, L.M., eds. LA-13478. Los Alamos, New Mexico: Los Alamos 
National Laboratory. TIC: 247225. 
162311 Perry, F.V.; Baldridge, W.S.; and DePaolo, D.J. 1987. Role of Asthenosphere and 
Lithosphere in the Genesis of Late Cenozoic Basaltic Rocks from the Rio Grande Rift 
and Adjacent Regions of the Southwestern United States. Journal of Geophysical 
Research, 92, 91939213. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 121 Septemb er 2003 
106634 Ratcliff, C.D.; Geissman, J.W.; Perry, F.V.; Crowe, B.M.; and Zeitler, P.K. 1994. 
Paleomagnetic Record of a Geomagnetic Field Reversal from Late Miocene Mafic 
Intrusions, Southern Nevada. Science, 266, 412-416. Washington, D.C.: American 
Association for the Advancement of Science. TIC: 234818. 
119693 Reamer, C.W. 1999. Issue Resolution Status Report (Key Technical Issue: Igneous 
Activity. Revision 2.) Letter from C.W. Reamer (NRC) to Dr. S. Brocoum 
(DOE/YMSCO), July 16, 1999 with enclosure. ACC: MOL.19990810.0639. 
106708 Rosenbaum, J.G.; Hudson, M.R.; and Scott, R.B. 1991. Paleomagnetic Constraints 
on the Geometry and Timing of Deformation at Yucca Mountain, Nevada. Journal 
of Geophysical Research, 96, (B2), 19631979. Washington, D.C.: American 
Geophysical Union. TIC: 225126. 
145359 Savage, J.C.; Connor, C.B.; Stamatakos, J.A.; Ferrill, D.A.; Hill, B.E.; Davis, J.L; 
Wernicke, B.P.; and Bennett, R.A. 1998. Detecting Strain in the Yucca Mountain 
Area, Nevada. Science, 282, (5391), 1007b. Washington, D.C.: American 
Association for the Advancement of Science. TIC: 243445. 
118952 Savage, J.C.; Svarc, J.L.; and Prescott, W.H. 1999. Strain Accumulation at Yucca 
Mountain, Nevada, 19831998. Journal of Geophysical Research, 104 (B8), 
1762717631. Washington, D.C.: American Geophysical Union. TIC: 245645. 
100075 Sawyer, D.A.; Fleck, R.J.; Lanphere, M.A.; Warren, R.G.; Broxton, D.E.; and 
Hudson, M.R. 1994. Episodic Caldera Volcanism in the Miocene Southwestern 
Nevada Volcanic Field: Revised Stratigraphic Framework, 40Ar/39Ar Geochronology, 
and Implications for Magmatism and Extension. Geological Society of America 
Bulletin, 106, (10), 13041318. Boulder, Colorado: Geological Society of America. 
TIC: 222523. 
101019 Smith, E.I.; Feuerbach, D.L.; Nauman, T.R.; and Faulds, J.E. 1990. The Area of 
Most Recent Volcanism Near Yucca Mountain, Nevada: Implications for Volcanic 
Risk Assessment. High-Level Radioactive Waste Management, Proceedings of the 
International Topical Meeting, Las Vegas, Nevada, April 8-12, 1990. 1, 8190. 
La Grange Park, Illinois: American Nuclear Society. TIC: 202058. 
158735 Smith, E.I.; Keenan, D.L.; and Plank, T. 2002. Episodic Volcanism and Hot 
Mantle: Implications for Volcanic Hazard Studies at the Proposed Nuclear Waste 
Repository at Yucca Mountain, Nevada. GSA Today, 12, (4), 410. 
Boulder, Colorado: Geological Society of America. TIC: 253146. 
138819 Stamatakos, J.A.; Connor, C.B.; and Martin, R.H. 1997. Quaternary Basin 
Evolution and Basaltic Volcanism of Crater Flat, Nevada, from Detailed Ground 
Magnetic Surveys of the Little Cones. Journal of Geology, 105, 319-330. 
Chicago, Illinois: University of Chicago. TIC: 245108. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 122 Septemb er 2003 
107250 Wernicke, B.P.; Christiansen, R.L.; England, P.C.; and Sonder, L.J. 1987. 
Tectonomagmatic Evolution of Cenozoic Extension in the North American 
Cordillera. Continental Extensional Tectonics. Coward, M.P.; Dewey, J.F.; and 
Hancock, P.L., eds. Special Publication No. 28, Pages 203221. Oxford, England: 
Geological Society. TIC: 225180. 
103485 Wernicke, B.; Davis, J.L.; Bennett, R.A.; Elosegui, P.; Abolins, M.J.; Brady, R.J.; 
House, M.A.; Niemi, N.A.; and Snow, J.K. 1998. Anomalous Strain Accumulation 
in the Yucca Mountain Area, Nevada. Science, 279, 20962100. New York, New 
York: American Association for the Advancement of Science. TIC: 235956. 
136262 Yogodzinski, G.M. and Smith, E.I. 1995. Isotopic Domains and the Area of Interest 
for Volcanic Hazard Assessment in the Yucca Mountain Area. Transactions of the 
American Geophysical Union, 76 (46), F669. Washington, D.C.: American 
Geophysical Union. TIC: 237939. 
8.2 CODES, STANDARDS, REGULATIONS, AND PROCEDURES 
164105 AP-SI.1Q, Rev. 5, ICN 1. Software Management. Washington, D.C.: 
U.S. Department of Energy, Office of Civilian Radioactive Waste Management. 
ACC: DOC.20030708.0001. 
164179 AP-SIII.9Q, Rev. 1, ICN 0. Scientific Analyses. Washington, D.C.: U.S. Department 
of Energy, Office of Civilian Radioactive Waste Management. 
ACC: DOC.20030708.0002. 
156605 10 CFR 63. Energy: Disposal of High-Level Radioactive Wastes in a Geologic 
Repository at Yucca Mountain, Nevada. Readily available. 
8.3 DATA, LISTED BY DATA TRACKING NUMBER 
149593 LA0004FP831811.002. Volume of Volcanic Centers in the Yucca Mountain Region. 
Submittal date: 04/14/2000. (Data are used for reference only). 
164712 LA0009FP831811.004. Summary Frequencies of Disruptive Volcanic Events. 
Submittal date; 09\05\2000. 
152659 LA0009FP831811.004. Data Summaries Supporting Computation of Volcanic Event 
Intersection Frequencies for the 70,000 MTU Repository Layout. Submittal date: 
09/14/2000. 
144279 LAFP831811AQ97.001. Chemical and Geochronology Data for the Revision and 
Final Publication of the Volcanism Synthesis Report. Submittal date: 08/29/1997. 
(Data are used for reference only). 
148234 MO0002PVHA0082.000. Probabilistic Volcanic Hazard Analysis for Yucca 
Mountain, Nevada. Submittal date: 02/17/2000. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 123 Septemb er 2003 
149605 MO0003YMP98126.001. Quaternary and Pliocene Basalt. Submittal date: 
03/02/2000. (Data are used for reference only). 
8.4 SOFTWARE 
152614 Dynamic Graphics. 1998. Software Code: EARTHVISION. 5.1. Silicon Graphics 
Indigo R4000. 10174-5.1-00. 
148560 LANL (Los Alamos National Laboratory). 2000. Software Routine: CFRAC.FOR 
V1.0. V1.0. 10254-1.0-00. 
148617 LANL. 2000. Software Routine: COMBDELD.FOR V1.0. V1.0. 10288-1.0-00. 
148562 LANL. 2000. Software Routine: COMBSF.FOR V1.0. V1.0. 10255-1.0-00. 
148561 LANL. 2000. Software Routine: COMBSM.FOR V1.0. V1.0. 10256-1.0-00. 
148535 LANL. 2000. Software Routine: CPDI.FOR V1.0. V1.0. 10257-1.0-00. 
148534 LANL. 2000. Software Routine: DCPELD.FOR V1.0. V1.0. 10258-1.0-00. 
148559 LANL. 2000. Software Routine: DILECDLH.FOR V1.0. V1.0. 10259-1.0-00. 
148558 LANL. 2000. Software Routine: DLECD.FOR V1.0. V1.0. 10260-1.0-00. 
148541 LANL. 2000. Software Routine: FIT2CNTR.FOR V1.0. V1.0. 10261-1.0-00. 
148532 LANL. 2000. Software Routine: FITCD.FOR V1.0. V1.0. 10262-1.0-00. 
148540 LANL. 2000. Software Routine: FITFIELD.FOR V1.0. V1.0. 10263-1.0-00. 
148557 LANL. 2000. Software Routine: FITIDSR.FOR V1.0. V1.0. 10264-1.0-00. 
148567 LANL. 2000. Software Routine: FKVH.FOR V1.0. V1.0. 10265-1.0-00. 
148546 LANL. 2000. Software Routine: FKVHLH.FOR V1.0. V1.0. 10266-1.0-00. 
148538 LANL. 2000. Software Routine: FKVPVH.FOR V1.0. V1.0. 10267-1.0-00. 
148551 LANL. 2000. Software Routine: FKVPVHLH.FOR V1.0. V1.0. 10268-1.0-00. 
148543 LANL. 2000. Software Routine: FPFGVH.FOR V1.0. V1.0. 10269-1.0-00. 
148553 LANL. 2000. Software Routine: FPFGVHLH.FOR V1.0. V1.0. 10270-1.0-00. 
148563 LANL. 2000. Software Routine: MARGIN.FOR V1.0. V1.0. 10271-1.0-00. 
148555 LANL. 2000. Software Routine: NECPDS.FOR V1.0. V1.0. 10272-1.0-00. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 124 Septemb er 2003 
148542 LANL. 2000. Software Routine: PFGVH.FOR V1.0. V1.0. 10273-1.0-00. 
148552 LANL. 2000. Software Routine: PFGVHLH.FOR V1.0. V1.0. 10274-1.0-00. 
148533 LANL. 2000. Software Routine: SFCD.FOR V1.0. V1.0. 10275-1.0-00. 
148571 LANL. 2000. Software Routine: SFIDSR.FOR V1.0. V1.0. 10276-1.0-00. 
148536 LANL. 2000. Software Routine: UZVH.FOR V1.0. V1.0. 10277-1.0-00. 
148545 LANL. 2000. Software Routine: UZVHLH.FOR V1.0. V1.0. 10278-1.0-00. 
148537 LANL. 2000. Software Routine: UZVPVH.FOR V1.0. V1.0. 10279-1.0-00. 
148547 LANL. 2000. Software Routine: UZVPVHLH.FOR V1.0. V1.0. 10280-1.0-00. 
148554 LANL. 2000. Software Routine: VHTIELHS.FOR V1.0. V1.0. 10281-1.0-00. 
148544 LANL. 2000. Software Routine: VHTREE.FOR V1.0. V1.0. 10282-1.0-00. 
148539 LANL. 2000. Software Routine: ZBCKVH.FOR V1.0. V1.0. 10283-1.0-00. 
148550 LANL. 2000. Software Routine: ZBCKVHLH.FOR V1.0. V1.0. 10284-1.0-00. 
8.5 OUTPUT DATA 
164712 LA0009FP831811.001. Compilation and Summaries of Data Supporting 
Computation of Volcanic Event Intersection Frequencies. Submittal date: 
09/01/2000. 
164714 LA0009FP831811.002. Summary Frequencies of Disruptive Volcanic Events. 
Submittal date: 09/05/2000. 
162670 LA0302BY831811.001. Summary Frequencies of Disruptive Volcanic Events. 
Submittal date: 02/05/03. 
163985 LA0303BY831811.001. Data for tables and figures used in ANL-MGR-GS-000001, 
REV01. Submittal date: 04/07/03. 
164713 LA0307BY831811.001. Formatted output data for TSPA. Submittal date: 07/29/03

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 I-1 September 2003 
ATTACHMENT I 
ADDRESSING YUCCA MOUNTAIN REVIEW PLAN FINAL REPORT ACCEPTANCE 
CRITERIA RELATED TO THE DEFINITION OF EVENTS WITH PROBABILITIES 
GREATER THAN 10-8 PER YEAR AND VOLCANIC DISRUPTION OF WASTE 
PACKAGES 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 I-2 September 2003 
INTENTIONALLY LEFT BLANK 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 I-3 September 2003 
ATTACHMENT I 
ADDRESSING YUCCA MOUNTAIN REVIEW PLAN FINAL REPORT ACCEPTANCE 
CRITERIA RELATED TO THE DEFINITION OF EVENTS WITH PROBABILITIES 
GREATER THAN 10-8 PER YEAR AND VOLCANIC DISRUPTION OF WASTE 
PACKAGES 
The probability of intersection of the repository by an ascending basaltic dike has been estimated 
to be 1.7  10-8 per year. Hence, to meet the requirements of 10 CFR 63.114(d), the probability 
of intersection has been identified as an event that must be evaluated as part of the analysis of 
repository postclosure performance. Section 1.5.2 of the YMRP (NRC 2003 [163274]) describes 
the review methods that apply to the description of site characterization activities, and 
Section 1.5.3 provides the acceptance criteria. Section 2.2.1.2.2.3 contains Acceptance Criteria 
related to the review of LA information about identification of events with probabilities greater 
than 10-8 per year. The following information identifies sections of this report that contain 
information relevant to future igneous events at Yucca Mountain. 
Section 1.5.2 Review Method 2: Summary of Site Characterization Results 
Review Method specifies that the LA must contain an overview of geology, consistent with other 
site characterization summaries, that includes 
(f) A summary of regional geomorphic, tectonic, seismic, and volcanic models 
(i.e., conceptual, technical basis, interpretation of data), with particular 
emphasis on those features, events, and processes that may have an effect on 
the repository operations and safety. 
FEPs associated with igneous activity and addressed by information in this report are identified 
in Section 6.1.2. The analysis report describes the volcanic history of the YMR and separates the 
Miocene eruptions of huge volumes of silicic tephra from the Pliocene and Quaternary eruptions 
of very modest amounts of basalt that ended with the eruption(s) at the Lathrop Wells cone about 
80,000 years ago. Characteristics of the Crater Flat structural domain are described in 
Section 6.4.1. The correlation of volcanism with features of the structural domain is described in 
Section 6.4.1.5. The relationship of volcanic source zones described in the Probabilistic 
Volcanic Hazards Analysis for Yucca Mountain, Nevada (PVHA) to the structural domain are 
described in Section 6.4.2. 
(i) A summary evaluation of volcanic probability 
The PVHA established that the annual probability of intersection of the repository by a basaltic 
dike is very low but still large enough that volcanism must be considered in the TSPA-LA. The 
estimate of the annual probability of intersection of the repository by an ascending basaltic dike 
was done using an expert elicitation process described in the PVHA. Topics of special interest 
include (a) discussion of PVHA results and uncertainty (Section 6.3.1.5), (b) consideration of 
alternative conceptual models (Section 6.3.1.6), (c) discussion of the significance of buried 
volcanic centers on PVHA results (Section 6.3.1.7), (d) discussion of alternative estimates of 
intersection probabilities, (e) discussion of the definitions and parameters of a volcanic event and 

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ANL-MGR-GS-000001 REV 01 I-4 September 2003 
implications for alternative probability calculations (Section 6.3.2), and (f) discussion of 
conceptual models of volcanism and formulation of probability models (Section 6.3.3). 
Section 1.5.3: Acceptance Criterion 2: The General Information Section of the License 
Application contains an adequate description of site characterization results. 
(1) A sufficient understanding is provided of current features and processes 
present in the Yucca Mountain region. 
FEPs associated with igneous activity and addressed by information in this report are identified 
in Section 6.1.2. The analysis report describes the volcanic history of the YMR and separates the 
Miocene eruptions of huge volumes of silicic tephra from the Pliocene and Quaternary eruptions 
of very modest amounts of basalt that ended with the eruption(s) at the Lathrop Wells cone about 
80,000 years ago. Characteristics of the Crater Flat structural domain are described in 
Section 6.4.1. The correlation of volcanism with features of the structural domain is described in 
Section 6.4.1.5. The relationship of volcanic source zones described in the Probabilistic 
Volcanic Hazards Analysis for Yucca Mountain, Nevada (PVHA) to the structural domain are 
described in Section 6.4.2. 
(2) An adequate understanding is provided of future events and processes likely 
to be present in the Yucca Mountain region that could affect repository 
safety. 
The PVHA established that the annual probability of intersection of the repository by a basaltic 
dike is very low but still large enough that volcanism must be considered in the TSPA-LA. The 
estimate of the annual probability of intersection of the repository by an ascending basaltic dike 
was done using an expert elicitation process described in the PVHA. Topics of special interest 
include (a) discussion of PVHA results and uncertainty (Section 6.3.1.5), (b) consideration of 
alternative conceptual models (Section 6.3.1.6), (c) discussion of the significance of buried 
volcanic centers on PVHA results (Section 6.3.1.7), (d) discussion of alternative estimates of 
intersection probabilities, (e) discussion of the definitions and parameters of a volcanic event and 
implications for alternative probability calculations (Section 6.3.2), and (f) discussion of 
conceptual models of volcanism and formulation of probability models (Section 6.3.3). 
For TSPA-LA, volcanic disruption of the repository will be modeled by two disruption 
scenarios. The first is a direct release scenario, which features a basaltic eruption through the 
repository, and ejection and dispersal of contaminated ash to the location of the reasonably 
maximally exposed individual. The second is an indirect release scenario, which features 
intrusion of a basaltic dike into the repository without eruption, damage to waste packages and 
exposure of the waste to transport by normal groundwater mechanisms. In each case, the dose is 
multiplied by the annual probability to provide a probability-weighted mean annual dose. The 
annual probability is documented in this report, and other reports document the other parameters 
needed to complete the models for the two scenarios. 

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Section 2.2.1.2.2.3 Identification of Events with Probabilities Greater Than 10-8 Per Year 
Acceptance Criterion 1: Events Are Adequately Defined. 
(1) Events or event classes are defined without ambiguity and used consistently in 
probability models, such that probabilities for each event or event class are 
estimated separately. 
For the PVHA, an expert panel was convened in 1995 to review all pertinent data relating to 
volcanism at Yucca Mountain and, based on these data, to quantify both the annual probability 
and associated uncertainty of a volcanic event intersecting a proposed repository sited at Yucca 
Mountain. The data the experts reviewed was comprehensive, consisting of two decades of data 
collected by volcanologists who conducted studies to quantify the probability that a future 
volcanic eruption would disrupt the proposed repository. PVHA methods and results are 
summarized in Section 6.3.1.5, and Section 6.3.2 describes how the experts defined a volcanic 
event. Based on the descrip tion in Section 6.3.2, although the experts defined a volcanic event 
differently, the product of the expert elicitation process was an unambiguous definition of a 
volcanic event, and the descriptions in Sections 6.3.2 and 6.3.3 show how the definitions were 
consistently used in the development and evaluation of probability models that supported the 
estimate of the probability of intersection of the proposed repository by a future igneous event. 
(2) Probabilities of intrusive and extrusive igneous events are calculated 
separately. 
Section 6.5.3 describes the results of the estimation of the probability of intersection of the LA 
repository footprint by an ascending basaltic dike. The section also describes the results of the 
estimation of the number of eruptive centers that could occur within the repository footprint. 
Probability values, presented in Table 22, show the annual frequency of intersection of the 
repository by a dike, the conditional probability of at least one eruptive center (given 
intersection), and the annual frequency of occurrence of one or more eruptive centers within the 
proposed repository. 
Acceptance Criterion 2: Probability Estimates For Future Events Are Supported By Appropriate 
Technical Bases. 
(1) Probabilities for future natural events have considered past patterns of the 
natural events in the Yucca Mountain region considering the likely future 
conditions and interactions of the natural and engineered system. These 
probability estimates have specifically included igneous events. 
Section 6.2 describes the volcanic history of the YMR. Section 6.3.1 describes the PVHA 
process and includes documentation of the measures used to include information about past 
patterns of igneous activity in the YMR were incorporated into alternative spatial and temporal 
distributions of potential future volcanic activity in the region (Section 6.3.1.3). Section 6.3.1.7 
describes the methods used to evaluate the significance of buried volcanic centers on the PVHA 
results, and Section 6.3.1.8 describes the measures used to include alternative estimates of the 
intersection probability. Section 6.3.2 includes examples of how information about vents and 
vent alignments in the YMR were incorporated into the probability calculations. 

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Acceptance Criterion 3: Probability Model Support Is Adequate. 
(1) Probability models are justified through comparison with output from 
detailed process- level models and/or empirical observations (e.g., laboratory 
testing, field measurements, or natural analogs, including Yucca Mountain 
site data). Specifically: 
(a) For infrequent events, the U.S. Department of Energy justifies, to the 
extent appropriate, proposed probability models with data from 
reasonably analogous systems. Analog systems should contain 
significantly more events that the Yucca Mountain system, to provide 
reasonable evaluations of probability model performance. 
Section 6.3.1.3 describes the temporal and spatial aspects of probability models and the methods 
that were used to ensure that alternative spatial and temporal models were considered by the 
experts and included in the development of probability models. Section 6.3.1.6 describes the 
consideration of alternative conceptual models of the tectonic environment of Yucca Mountain 
that have emerged since the PVHA was completed. Section 6.3.1.7 describes the methods used 
to consider the significance of buried volcanic centers on the PVHA results. Section 6.3.1.8 
describes the alternative estimates of intersection probability and provides comments about the 
relevance of each of the models to estimating the probability of intersection. Section 6.3.2 
describes definitions and parameters of a volcanic event and describes implications of these 
elements for alternative probability calculations. Section 6.3.2.1 specifically addresses use of 
analog information and describes evidence from analog sites related to determining whether 
dikes or dike systems can reach the near-surface without any portion of the system erupting. 
Data from the analog systems shows that field observations do not support the multipliers 
assigned for undetected intrusive events by the NRC. Rather, the analog information supports 
the interpretation that the intrusion/extrusion ratio is close to 1. 
(b) The U.S. Department of Energy justifies, to the extent appropria te, the 
ability of probability models to produce results consistent with the 
timing and characteristics (e.g., location and magnitude) of successive 
past events in the Yucca Mountain system. 
The DOE probability estimate for intersection of the proposed repository by a basaltic dike is a 
combined estimate developed from inputs of 10 experts but modified to reflect the current 
design. The experts models were based on the igneous characteristics of the YMR; hence, the 
probability models they developed were consistent with the timing and characteristics of past 
events in the YMR. The information used by the experts and the results of their deliberations are 
extensively documented in the PVHA (CRWMS M&O 1996 [100116]). The ability of the 
probability model to produce results consistent with timing and characteristics of past events is 
described in detail in Section 6.5.3, and the effects of new aeromagnetic information on the 
hazard estimate is evaluated in Section 6.5.4. 
(c) The U.S. Department of Energy probability models for natural events 
use underlying geologic bases (e.g., tectonic models) that are consistent 

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with other relevant features, events, and processes evaluated, using 
Section 2.2.1.2.1 
Consistency of experts models with tectonic models is discussed in Section 6.4, which presents 
a detailed description of the Crater Flat structural domain. Consideration of relevant features, 
events and processes is discussed in Section 6.1.2. 
Acceptance Criterion 4: Probability Model Parameters Have Been Adequately Established. 
(1) Parameters used in probability models are technically justified and 
documented by the U.S. Department of Energy. Specifically: 
(a) Parameters for probability models are constrained by data from the 
Yucca Mountain region and engineered repository system to the extent 
practical. 
Section 6.2 describes the volcanic history of the YMR. Section 6.3.1 describes the PVHA 
process and includes documentation of the measures used to include information about past 
patterns of igneous activity in the YMR were incorporated into alternative spatial and temporal 
distributions of potential future volcanic activity in the region (Section 6.3.1.3). Section 6.3.1.7 
describes the methods used to evaluate the significance of buried volcanic centers on the PVHA 
results, and Section 6.3.1.8 describes the measures used to include alternative estimates of the 
intersection probability. Section 6.3.2 includes examples of how information about vents and 
vent alignments in the YMR were incorporated into the probability calculations. 
(b) The U.S. Department of Energy appropriately establishes reasonable and 
consistent correlations between parameters. 
The volcanic history of the YMR is described in Section 6.2. The correlations between 
volcanism and the internal structure and boundaries of the Crater Flat basin are described in 
Section 6.4.1.5, and the relationship between Crater Flat structural features and the probability of 
dike intersection with the repository is described in Section 6.4.2. The reasonableness and 
consistency of the relationship between intrusive and extrusive event, and the effects of 
consideration of alternative models of the relationship based on analog information, is described 
in detail in Section 6.3.2.1. Alternative event (dike) lengths and their consistency with data from 
the YMR and with data from analogs are considered in Section 6.3.2.2. Conceptual models of 
volcanism and the use of these models in the development of probability models are described in 
Section 6.3.3. 
(c) Where sufficient data do not exist, the definition of parameter values and 
conceptual models is based on appropriate use of other sources, such as 
expert elicitation conducted in accordance with appropriate guidance. 
The DOE probability estimate is based on the results of formal elicitations of 10 experts 
(Section 6.3.1.1). The data considered by the experts was described in detail in the PVHA report 
(CRWMS M&O 1996 [100116], e.g., Table 3-1). The development of the probability estimate is 
summarized in Section 6.3 of this report, and the elicitation process is summarized in Section 
6.3.1.4. Elicitation results are extensively documented in the PVHA report (CRWMS 

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M&O 1996 [100116], Sections 4.1 and 4.2) and are summarized in this report in Section 6.3.1.5. 
DOE and NRC guidance relevant to the elicitation process and adherence to that guidance during 
the elicitation process was described in the PVHA (CRWMS M&O 1996 [100116], 
Section 2.1.1). 
Acceptance Criterion 5: Uncertainty In Event Probability Is Adequately Evaluated. 
(1) Probability values appropriately reflect uncertainties. Specifically: 
(a) The U.S. Department of Energy provides a technical basis for 
probability values used, and the values account for the uncertainty in the 
probability estimates. 
The technical basis for the probability values described in this report are extensively documented 
in Sections 6.3.2 and 6.4, and the PVHA process is summarized in Section 6.3.1. The 
formulations and methods used to recalculate the frequency of intersection, develop distributions 
for length and orientation of dikes, and estimate the number of eruptive centers within the 
proposed repository footprint are described in Sections 6.5.1 and 6.5.2. The results of the 
calculations are described in Section 6.5.3. 
Uncertainties in the PVHA elicitation process are summarized in Section 6.3.1.5, and 
uncertainties in the technical basis supporting the probability values calculated in this report are 
described in Sections 6.3.2 and 6.3.3. The correlation of volcanism in the YMR with the Crater 
Flat structural domain is discussed in Section 6.4.1.5, and the relationship of the PVHA volcanic 
source zones to Crater Flat structural features and the probability of dike intersection is described 
in Section 6.4.2. Propagation of uncertainties in the analyses are specifically described in 
Section 6.5.3 and are shown, for example, in Figure 20. 
(b) The uncertainty for reported probability values adequately reflects the 
influence of parameter uncertainty on the range of model results 
(i.e., precision) and the model uncertainty, as it affects the timing and 
magnitude of past events (i.e., accuracy). 
Propagation of uncertainties in the analyses are specifically described in Section 6.5.3 and are 
shown, for example, in Figure 20. Methods to include uncertainties associated with specific 
parameter are described in the formulation of the probability models in Section 6.5.1. 
Acceptance criteria related to the volcanic disruption of waste packages are presented in 
Section 2.2.1.3.10.3 of the YMRP (NRC 2003 [163274] NUREG-1804). Because this section of 
the review plan addresses the consequences of an igneous event intersecting the repository, the 
applicability of the information in this report to the acceptance criteria is limited. Information in 
this report about the segment lengths and orientations of dikes that intersect the repository, the 
number of eruptive centers that could form along a dike segment within the repository footprint, 
and the spacing between centers is needed to evaluate eruptive processes. However, this report 
does not address issues related to the nature of the possible interactions between a dike and 
repository drifts; nor does this report address waste package damage caused by exposure to 
magmatic conditions or the incorporation of such damage models into TSPA-LA. 

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Acceptance Criterion 1: System Description And Model Integration Are Adequate. 
(1) Total system performance assessment adequately incorporates important 
design features, physical phenomena, and couplings, and uses consistent and 
appropriate assumptions throughout the volcanic disruption of waste packages 
abstraction process. 
The element is not addressed by information in this report. Information about the effects of 
exposure of waste packages to the environmental conditions attending intersection of the 
repository by a basaltic dike will be provided in a new report, Igneous Intrusion Impacts on 
Waste Package and Waste Form. 
(2) Models used to assess volcanic disruption of waste packages are consistent 
with physical processes generally interpreted from igneous features in the 
Yucca Mountain region and/or observed at active igneous systems. 
Information in this report addresses the relationship between an ascending dike and the number 
of eruptive centers that could occur within the repository footprint (Section 6.5.3). The 
formulations and implementation methods needed to support the analyses are described in 
Sections 6.5.1 and 6.5.2, respectively. Models that are used to support the analysis of the effects 
of exposure of waste packages to the environmental conditions attending intersection of the 
repository by a basaltic dike will be described in a new report, Igneous Intrusion Impacts on 
Waste Package and Waste Form. 
(3) Models account for changes in igneous processes that may occur from 
interaction with engineered repository systems. 
Changes in igneous processes that may occur from interactions with the engineered repository 
systems are not addressed in this report. Changes in igneous processes will be addressed in the 
update of the report, Dike Propagation Near Drifts and in the new report, Igneous Intrusion 
Impacts on Waste Package and Waste Form. 
(4) Guidance in NUREG-1297 and NUREG-1298 (Altman et al. 1998 a, b) or 
other acceptable approaches is followed. 
This acceptance criterion is not applicable to this report. The information in this report was not 
developed using peer review methods (NUREG-1297), and no preexisting data was qualified 
(NUREG-1298) to support the analyses in this report. 
Acceptance Criterion 2: Data Are Sufficient For Model Justification. 
(1) Parameter values used in the license application to evaluate volcanic 
disruption of waste packages are sufficient and adequately justified. Adequate 
descriptions of how the data were used, interpreted, and appropriately 
synthesized into the parameters are provided. 
The parameters developed in this report and needed in the analysis of volcanic disruption of 
waste packages are the results of calculations of the length and orientation of dikes and the 

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ANL-MGR-GS-000001 REV 01 I-10 September 2003 
number of eruptive centers within the repository. These parameters are documented in 
Section 6.5.3. 
(2) Data used to model processes affecting volcanic disruption of waste packages 
are derived from appropriate techniques. These techniques may include sitespecific 
field measurements, natural analog investigations, and laboratory 
experiments. 
Information about, and modeling of, processes affecting volcanic disruption of waste packages 
will be provided in the following analysis reports: 
  Characterize Eruptive Processes and Ash Redistribution at Yucca Mountain, Nevada 
  Dike Propagation Near Drifts 
  Igneous Intrusion Impacts on Waste Package and Waste Form. 
Provides the results of calculations of the length and orientation of dikes and the number of 
eruptive centers within the repository. These parameters are documented in Section 6.5.3. 
(3) Sufficient data are available to integrate features, events, and processes, 
relevant to volcanic disruption of waste packages into process-level models, 
including determination of appropriate interrelationships and parameter 
correlations. 
Table 9 identifies the features, events and processes (FEPs) that are included in this analysis 
report and provides a summary of the disposition of each FEP in the TSPA-LA. However, this 
report does not provide that FEPs disposition documentation. That documentation will be 
provided in the update of the disruptive events FEPs analysis report (CRWMS M&O 2000 
[151553]). 
(4) Where sufficient data do not exist, the definition of parameter values and 
associated conceptual models is based on appropriate use of expert elicitation, 
conducted in accordance with NUREG-1563 (Kotra et al 1996). If other 
approaches are used, the U.S. Department of Energy adequately justifies their 
use. 
The DOE probability estimate is based on the results of formal elicitations of 10 experts 
(Section 6.3.1.1). The data considered by the experts was described in detail in the PVHA report 
(CRWMS M&O 1996 [100116], e.g., Table 3-1). The development of the probability estimate is 
summarized in Section 6.3 of this report, and the elicitation process is summarized in Section 
6.3.1.4. Elicitation results are extensively documented in the PVHA report (CRWMS 
M&O 1996 [100116], Sections 4.1 and 4.2) and are summarized in this report in Section 6.3.1.5. 
DOE and NRC guidance relevant to the elicitation process and adherence to that guidance during 
the elicitation process was described in the PVHA (CRWMS M&O 1996 [100116], 
Section 2.1.1). 
Acceptance Criterion 3: Data Uncertainty Is Characterized And Propagated Through The Model 
Abstraction. 

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(1) Models use parameter values, assumed ranges, probability distributions, and 
bounding assumptions that are technically defensible, and reasonably account 
for uncertainties and variabilities, and do not result in an under-representation 
of the risk estimate. 
The formulations support the probability estimate and propagate parameter uncertainties, 
methods used to implement the analyses, and results of the analyses are described in detail in 
Sections 6.5.1, 6.5.2, and 6.5.3, respectively, of this report. In addition, the definitions and 
parameters of a volcanic event and their implications for alternative probability calculations are 
described in Section 6.3.2. PVHA results and associated uncertainties are discussed in 
Section 6.5.1.3. Consideration of alternative probability models in the PVHA process is 
described in Section 6.5.1.4, and the significance of buried volcanic centers on the PVHA results 
is described in Section 6.5.1.5. Alternative estimates of the intersection probability are described 
in Section 6.5.1.6. The robustness of the estimate of the probability of intersection has been 
demonstrated through sensitivity analyses (e.g., Brocoum 1997 [147772]), and some published 
estimates of the probability of intersection of the repository by a dike are presented in Table 13. 
(2) Parameter uncertainty accounts quantitatively for the uncertainty in parameter 
values observed in site data and the available literature (i.e., data precision), 
and the uncertainty in abstracting parameter values to process-level models 
(i.e., data accuracy). 
The uncertainties associated with the temporal and spatial aspects of models of the probability of 
intersection are described in Section 6.3.1.3. PVHA results and uncertainty are described in 
Section 6.3.1.5. Similarly, the formulatio ns, implementation, and results of the recalculation of 
the frequency of intersection and the development of distributions for length and orientation of 
dikes are explained in Sections 6.5.1, 6.5.2, and 6.5.3, respectively. These sections also explain 
the development of the probability distributions for the number of eruptive center that could 
occur within the repository. The process for abstracting the recalculated values is not addressed 
in this report. 
(3) Where sufficient data do not exist, the definition of parameter values and 
associated uncertainty is based on appropriate use of expert elicitation, 
conducted in accordance with NUREG-1563 (Kotra et al 1996). If other 
approaches are used, the U.S. Department of Energy adequately justifies their 
use. 
The DOE probability estimate is based on the results of formal elicitations of 10 experts 
(Section 6.3.1.1). The data considered by the experts was described in detail in the PVHA report 
(CRWMS M&O 1996 [100116], e.g., Table 3-1). The development of the probability estimate is 
summarized in Section 6.3 of this report, and the elicitation process is summarized in Section 
6.3.1.4. Elicitation results are extensively documented in the PVHA report (CRWMS 
M&O 1996 [100116], Sections 4.1 and 4.2) and are summarized in this report in Section 6.3.1.5. 
DOE and NRC guidance relevant to the elicitation process and adherence to that guidance during 
the elicitation process was described in the PVHA (CRWMS M&O 1996 [100116], 
Section 2.1.1). 

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Acceptance Criterion 4: Model Uncertainty Is Characterized And Propagated Through The 
Model Abstraction. 
(1) Alternative modeling approaches to volcanic disruption of the waste package 
are considered and are consistent with available data and current scientific 
understandings, and the results and limitations are appropriately considered in 
the abstraction. 
This report does not address modeling of the volcanic disruption of waste packages. That 
modeling will be described in the report, Igneous Intrusion Impacts on Waste Package and 
Waste Form. 
(2) Uncertainties in abstracted models are adequately defined and documented, 
and effects of these uncertainties are assessed in the total system performance. 
This report does not address abstractions of models and propagation of uncertainty through the 
abstraction process. 
(3) Consideration of conceptual model uncertainty is consistent with available site 
characterization data, laboratory experiments, field measurements, natural 
analog information and process- level modeling studies; and the treatment of 
conceptual model uncertainty does not result in an under-representation of the 
risk estimate. 
This report does not directly address the processes and associated models of volcanic disruption 
of waste packages. The processes and modeling will be described in the report, Igneous 
Intrusion Impacts on Waste Package and Waste Form. 
Uncertainties in conceptual models used to estimate the probability of intersection of the 
repository, distributions of dike length and orientation, and the number of eruptive centers within 
the proposed repository are explained in Section 6.5.1, which describes the formulation of the 
analyses. 
Acceptance Criterion 5: Model Abstraction Output Is Supported By Objective Comparisons. 
This report does not address model abstraction. 

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ATTACHMENT II 
DEVELOPMENT OF FOOTPRINT POLYGON 
FOR THE PROPOSED REPOSITORY 

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INTENTIONALLY LEFT BLANK 

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ATTACHMENT II 
DEVELOPMENT OF FOOTPRINT POLYGON 
FOR THE PROPOSED REPOSITORY 
The coordinates of the emplacement drifts for the LA repository design were obtained from the 
Repository/PA IED Subsurface Facilities Plan (BSC 2002 [159527]). These coordinates are 
given in terms of the Nevada State Plane Coordinate System, Central Zone. The coordinate 
system used in the PVHA hazard assessment is UTM. The Nevada State Plane coordinates for 
the emplacement drifts were transformed to UTM (Zone 11) using the coordinate conversion 
utility in EarthVision 5.1 (STN: 10174-5.1-00 [152614]). The transformed coordinates are 
listed in Table II-1. 
The calculations performed in this scientific analysis input data from files that contain the 
vertices of a polygon for the proposed repository footprint. For the purpose of this analysis, the 
repository footprint is defined as the outline of the waste emplacement area. A polygon was 
constructed to encompass the emplacement drifts in panels 1, 2, 3, and 5 of the LA repository 
design. A buffer zone was added around the emplacement area defined by the drift coordinates 
in Table II-1 to account for the effect of eruptive conduit size on the calculation of the frequency 
of dike intersection and the distribution for number of eruptive centers within the repository 
footprint. The mean of the distribution for conduit diameter given in CRWMS M&O (2000 
[151551]) is approximately 52.2 meters. Adding the emplacement drift half-width of 
2.75 meters gives a buffer zone width of 55 meters. The resulting polygon vertices were placed 
in input file LA2002.FP used in the calculations presented in this report. The footprint polygon 
file is listed below and is shown in Figure 16, Section 6.5. 
**** File: LA2002.fp**** 
LA 2002 Footprint Panels 1, 2, 3, & 5 
31 
547.741 4078.280 
547.735 4077.339 
547.755 4076.323 
547.840 4076.095 
547.909 4076.060 
548.354 4076.207 
548.389 4076.276 
548.468 4076.473 
548.530 4077.601 
548.577 4078.554 
548.619 4079.420 
548.688 4079.474 
549.066 4079.595 
549.101 4079.664 
549.216 4080.213 
549.662 4081.128 
549.584 4081.272 
549.441 4081.365 
548.997 4081.219 
549.018 4081.512 
548.949 4081.547 
548.434 4081.375 
547.959 4081.134 
547.782 4080.990 
547.658 4080.810 

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547.394 4080.211 
547.328 4079.167 
547.384 4078.588 
547.418 4078.513 
547.528 4078.410 
547.741 4078.280 
Table II-1. Proposed Repository Drift Coordinates for License Application 
Design 
East Side West Side 
Zone Drift 
UTM 
Easting 
(km) 
UTM 
Northing 
(km) 
UTM 
Easting 
(km) 
UTM 
Northing 
(km) 
2 1 548.966 4081.495 548.434 4081.320 
2 2 548.962 4081.408 548.392 4081.221 
3 2 548.364 4081.212 547.959 4081.079 
2 3 548.921 4081.310 548.351 4081.122 
3 3 548.323 4081.113 547.782 4080.935 
2 4 548.879 4081.211 548.309 4081.023 
3 4 548.281 4081.014 547.711 4080.827 
2 1 549.441 4081.310 548.997 4081.164 
2 5 548.837 4081.112 548.267 4080.925 
3 5 548.239 4080.915 547.669 4080.728 
3 6 547.627 4080.629 548.198 4080.816 
2 6 548.226 4080.826 548.796 4081.013 
2 2 548.956 4081.065 549.532 4081.255 
2 3 549.582 4081.186 548.914 4080.966 
2 7 548.754 4080.913 548.184 4080.726 
3 7 548.156 4080.717 547.586 4080.529 
3 8 547.544 4080.431 548.114 4080.618 
2 8 548.142 4080.627 548.713 4080.815 
2 4 548.872 4080.868 549.610 4081.110 
2 5 549.563 4081.009 548.831 4080.769 
2 9 548.671 4080.716 548.101 4080.528 
3 9 548.073 4080.519 547.503 4080.332 
3 10 547.446 4080.228 548.032 4080.421 
2 10 548.061 4080.430 548.626 4080.616 
2 6 548.770 4080.664 549.511 4080.907 
2 7 549.459 4080.805 548.738 4080.567 
2 11 548.622 4080.529 548.046 4080.340 
3 11 547.994 4080.323 547.425 4080.136 
3 12 547.421 4080.049 547.990 4080.236 
2 12 548.042 4080.253 548.618 4080.443 
2 8 548.735 4080.481 549.408 4080.703 
2 9 549.356 4080.601 548.730 4080.394 
2 13 548.613 4080.356 548.038 4080.167 
3 13 547.986 4080.150 547.417 4079.963 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 II-5 September 2003 
Table II-1. Proposed Repository Drift Coordinates for License 
Application Design (Continued) 
East Side West Side 
Zone Drift 
UTM 
Easting 
(km) 
UTM 
Northing 
(km) 
UTM 
Easting 
(km) 
UTM 
Northing 
(km) 
3 14 547.412 4079.876 547.981 4080.063 
2 14 548.033 4080.080 548.609 4080.269 
2 10 548.726 4080.307 549.304 4080.498 
2 11 549.253 4080.395 548.722 4080.221 
2 15 548.605 4080.183 548.030 4079.993 
3 15 547.978 4079.977 547.407 4079.789 
3 16 547.404 4079.703 547.973 4079.890 
2 16 548.025 4079.907 548.601 4080.096 
2 12 548.718 4080.134 549.201 4080.293 
2 13 549.164 4080.196 548.713 4080.048 
2 17 548.596 4080.009 548.021 4079.820 
3 17 547.969 4079.803 547.399 4079.616 
3 18 547.395 4079.529 547.965 4079.717 
2 18 548.016 4079.733 548.593 4079.923 
2 14 548.710 4079.962 549.142 4080.104 
2 15 549.115 4080.010 548.705 4079.875 
2 19 548.588 4079.836 548.012 4079.647 
3 19 547.961 4079.630 547.391 4079.443 
3 20 547.387 4079.356 547.956 4079.543 
2 20 548.008 4079.560 548.584 4079.750 
2 16 548.701 4079.789 549.106 4079.921 
2 17 549.087 4079.830 548.696 4079.702 
2 21 548.580 4079.663 548.003 4079.474 
3 21 547.951 4079.457 547.382 4079.269 
3 22 547.381 4079.184 547.948 4079.370 
2 22 548.000 4079.387 548.575 4079.576 
2 18 548.693 4079.615 549.067 4079.738 
2 19 549.049 4079.647 548.688 4079.529 
2 23 548.571 4079.490 547.995 4079.300 
3 23 547.946 4079.284 547.389 4079.101 
3 24 547.396 4079.018 547.962 4079.204 
1 1 548.112 4079.254 548.566 4079.403 
1 2 548.563 4079.316 548.012 4079.135 
3 25 547.959 4079.118 547.403 4078.935 
3 26 547.411 4078.852 547.954 4079.031 
1 3 548.006 4079.048 548.558 4079.230 
1 4 548.554 4079.143 548.002 4078.961 
3 27 547.950 4078.944 547.419 4078.770 
3 28 547.426 4078.687 547.946 4078.858 
1 5 548.003 4078.877 548.550 4079.056 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 II-6 September 2003 
Table II-1. Proposed Repository Drift Coordinates for License 
Application Design (Continued) 
East Side West Side 
Zone Drift 
UTM 
Easting 
(km) 
UTM 
Northing 
(km) 
UTM 
Easting 
(km) 
UTM 
Northing 
(km) 
1 6 548.546 4078.970 548.044 4078.805 
3 29 547.944 4078.772 547.437 4078.605 
3 30 547.470 4078.531 547.977 4078.697 
1 7 548.541 4078.883 548.128 4078.747 
3 31 548.074 4078.645 547.528 4078.465 
1 8 548.538 4078.796 548.215 4078.691 
5 1 548.525 4078.537 547.794 4078.297 
5 2 547.793 4078.211 548.520 4078.450 
5 3 548.516 4078.363 547.791 4078.125 
5 4 547.790 4078.040 548.511 4078.277 
5 5 548.508 4078.190 547.789 4077.954 
5 6 547.788 4077.869 548.503 4078.103 
5 7 548.499 4078.017 547.786 4077.783 
5 8 547.786 4077.697 548.495 4077.930 
5 9 548.491 4077.843 547.784 4077.612 
5 10 547.783 4077.526 548.486 4077.757 
5 11 548.483 4077.670 547.785 4077.441 
5 12 547.787 4077.356 548.478 4077.583 
5 13 548.473 4077.497 547.788 4077.272 
5 14 547.789 4077.187 548.469 4077.410 
5 15 548.465 4077.324 547.792 4077.102 
5 16 547.793 4077.018 548.461 4077.237 
5 17 548.456 4077.150 547.795 4076.933 
5 18 547.800 4076.849 548.453 4077.064 
5 19 548.448 4076.977 547.805 4076.766 
5 20 547.807 4076.681 548.444 4076.890 
5 21 548.440 4076.804 547.807 4076.596 
5 22 547.805 4076.510 548.436 4076.717 
5 23 548.431 4076.630 547.806 4076.425 
5 24 547.807 4076.340 548.428 4076.544 
5 25 548.416 4076.455 547.815 4076.257 
5 26 547.843 4076.181 548.381 4076.358 
5 27 548.337 4076.259 547.892 4076.113 
OUTPUT DATA. DTN: LA0303BY831811.001 [163985] 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-1 September 2003 
ATTACHMENT III 
DEVELOPMENT OF DISTRIBUTIONS FOR NUMBER OF 
ERUPTIVE CENTERS PER VOLCANIC EVENT AND AVERAGE SPACING 
BETWEEN ERUPTIVE CENTERS 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-2 September 2003 
INTENTIONALLY LEFT BLANK 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-3 September 2003 
ATTACHMENT III 
DEVELOPMENT OF DISTRIBUTIONS FOR NUMBER OF 
ERUPTIVE CENTERS PER VOLCANIC EVENT AND AVERAGE SPACING 
BETWEEN ERUPTIVE CENTERS 
III.1 INTRODUCTION 
This attachment presents the derivation of discrete distributions for the number of eruptive 
centers per volcanic event, nEC, and the average spacing between eruptive centers. These 
assessments are derived from the PVHA experts assessments of the number of volcanic events 
at the three Quaternary volcanic centers in the site region, Lathrop Wells (LW), Sleeping Butte 
(SB), and Northwest Crater Flat (NWCF) using the first two assumptions described in Section 5. 
As defined in the PVHA (CRWMS M&O 1996 [100116]), the number of eruptive centers at 
each of these sites is: two at Sleeping Butte (Little Black Peak and Hidden Cone); five at Crater 
Flat (Little Cones southwest, Little Cones northeast, Red Cone, Black Cone, and Makani Cone); 
and one at Lathrop Wells. 
III.2 ILLUSTRATION OF THE PROCESS 
The process is illustrated using the assessments of Alex McBirney (AM) [from Table AM-1, 
p. AM-13 of Appendix E in CRWMS M&O (1996 100116])]. For Lathrop Wells (LW), AM 
assigned probabilities of 0.3, 0.2, 0.4, and 0.1 to there having been 1, 2, 3, or 4 volcanic events, 
respectively. If only one event occurred, then the data from LW are one event with one eruptive 
center per event (nEC = 1). If there were two events, then the data are two events with nEC = 1. 
For the three and four volcanic eve nt scenarios the data are three events with nEC = 1 and four 
events with nEC = 1, respectively. These assessments are summarized in Table III-1. 
For Sleeping Butte (SB), AM assigned probabilities of 0.05, 0.8, and 0.15 to there being 1, 2, or 
3 volcanic events, respectively. For the one event scenario, the data are one event with nEC = 2 
(Hidden Cone and Little Black Peak). For the two-event scenario, the data are two events with 
nEC = 1. For the three-event scenario, the data are three events with nEC = 1. 
For Northwest Crater Flat (NWCF), AM assigned probabilities of 0.9, 0.05, 0.025, 0.015, and 
0.01 to there having been 1, 2, 3, 4, or 5 volcanic events, respectively. For the one event 
scenario, the data are one event with nEC = 5 (Little Cones SW, Little Cones NE, Red Cone, 
Black Cone, and Makani Cone). For the two-event scenario, AM linked Little Cones (SW and 
NE), Red Cone, and Black Cone into one event and considered Makani Cone to be the second 
event. Thus, the data are one event with nEC = 4 and one event with nEC = 1. For the three-event 
scenario, AM considered Red Cone and Black Cone to be one event, Little Cones SW and NE to 
be one event, and Makani Cone to be the third event. Thus, the data are two events with nEC = 2 
and one event with nEC = 1. For the four-event scenario, AM considered Little Cones SW and 
NE to be one event, and Red Cone, Black Cone, and Makani Cone to each be separate events. 
Thus, the data are one event with nEC = 2 and four events with nEC = 1. Finally, for the 
five-event scenario, the data are five events with nEC = 1. 
The PVHA experts defined their assessments at each of the volcanic centers to be independent of 
the assessments at the other centers. As a result, for the assessments from Alex McBirney, there 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-4 September 2003 
are 435 = 60 possible combined scenarios for the number of Quaternary volcanic events. 
Each of these combined scenarios represents a possible empirical data set for evaluating the 
distribution for nEC. For example, if LW scenario 1, SB scenario 1, and NWCF scenario 1 are 
the correct assessments for the number of events, then the combined data set consists of one 
event with nEC = 1, one event with nEC = 2, and one event with nEC = 5. The resulting empirical 
distribution defining the relative frequency for various values of nEC is: 
333 . 0 3 / 1 ) 5 ( 
0 3 / 0 ) 4 ( 
0 3 / 0 ) 3 ( 
333 . 0 3 / 1 ) 2 ( 
333 . 0 3 / 1 ) 1 ( 
= = = 
= = = 
= = = 
= = = 
= = = 
EC
EC 
EC 
EC 
EC 
n P 
n P 
n P
n P 
n P 
The joint probability that this combined scenario represents the correct data is the product of the 
three independent probabilities for each scenario and is equal to 0.30.050.9 = 0.0135. There 
are 59 other possible combined data sets, each resulting in an empirical distribution for nEC. The 
weighted average of these is used to represent the expected distribution for nEC based on the 
assessments of Alex McBirney. 
A similar process is followed to compute the average spacing between eruptive centers. 
Whenever a volcanic event is defined to contain more than one of the eruptive centers, then the 
assessment provides a data point that can be used to evaluate the average spacing between 
eruptive centers. In the above combined scenario, there are two volcanic events with multiple 
eruptive centers. The single event at Sleeping Butte consists of eruptive centers at Little Black 
Peak and Hidden Cone. These cones are located 2.45 kilometers apart. The single event at 
Crater Flat consists of five eruptive centers. The distance between Makani Cone and Little 
Cones SW is 11.19 kilometers. Dividing this by 4, which is the number of intervals between 
eruptive centers, gives an average spacing of 2.80 kilometers. Thus, the combined scenario 
provides an average value of 2.6 kilometers based on two data points. The process is repeated 
for the 59 other scenarios, and the weighted average provides the expected average spacing 
between eruptive centers. In performing this calculation, those scenarios that result in only 
volcanic events with no multiple eruptive centers are removed from the weighting process. 
Calculation of Empirical Distribution for Average Spacing of Eruptive Centers 
Both the previous revision to this scientific analysis report and this current revision incorporate 
the empirical distribution for the average spacing between eruptive centers into the calculation of 
the conditional probability for the number of eruptive centers within the repository footprint. For 
the example scenario presented in the previous paragraph, the empirical distribution consists of a 
sample of two points, 2.45 kilometers with a probability of 0.5 and 2.80 kilometers, with a 
probability of 0.5. This distribution is weighted by the probability for the scenario of 0.0135. 
Repeating the process for the 59 other scenarios, weighting each empirical distribution by its 
scenario probability provides a composite empirical distribution for the average spacing between 
eruptive centers in future volcanic events. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-5 September 2003 
III.3 CALCULATION INPUT AND RESULTS 
The inputs to the calculation are the distributions for the number of volcanic events represented 
by the mapped Quaternary volcanoes defined by the PVHA experts and the locations of the 
volcanoes. Tables III-1 through III-10 summarize the interpretations of the assessments made by 
the 10 PVHA experts. 
Table III-1. Assessments from Alex McBirneys Volcanic Hazard Model 
Number of Events with nEC = Volcanic 
Center Scenario 
Number of 
Events * Probability 1 2 3 4 5 
Lathrop Wells 1 1 
LW 
0.3 1 
2 2 
LW, LW 
0.2 2 
3 3 
LW, LW, LW 
0.4 3 
4 4 
LW, LW, LW, 
LW 
0.1 4 
Sleeping 
Butte 
1 1 
LBP+HC 
0.05 1 
2 2 
LBP, HC 
0.8 2 
3 3 
LBP, HC, ? 
0.15 3 
Crater Flat 1 1 
MC+BC+RC+ 
LCne+LCsw 
0.9 1 
2 2 
MC, BC+RC+ 
LCne+LCsw 
0.05 1 1 
3 3 
MC, BC+RC, 
LCne+LCsw 
0.025 1 2 
4 4 
MC, BC, RC, 
LCne+LCsw 
0.015 3 1 
5 5 
MC, BC, RC, 
LCne, LCsw 
0.01 5 
DTN: MO0002PVHA0082.000 [148234] 
Source: CRWMS M&O (1996 [100116], Appendix E, Table AM-1, p. AM-13) 
NOTE: *LW = Lathrop Wells; HC = Hidden Cone; LBP = Little Black Peak; MC = Makani Cone; 
BC = Black Cone; RC = Red Cone; Lcne = Little Cones North East; LCsw = Little 
Cones southwest, ? undetected. A + indicates eruptive centers considered to be part 
of a single volcanic event. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-6 September 2003 
Table III-2. Assessments from Bruce Crowes Volcanic Hazard Model 
Number of Events with nEC = Volcanic 
Center Scenario 
Number of 
Events * Probability 1 2 3 4 5 
Lathrop Wells 1 1 
LW 
0.9 1 
2 2 
LW, LW 
0.06 2 
3 3 
LW, LW, LW 
0.03 3 
4 4 
LW, LW, LW, 
LW 
0.01 4 
Sleeping Butte 1 1 
LBP+HC 
0.35 1 
2 2 
LBP, HC 
0.45 2 
3 3 
LBP, HC, ? 
0.2 3 
Crater Flat 1 1 
MC+BC+RC+ 
LCne+LCsw 
0.1 1 
2 2 
MC+BC, 
RC+LCne+LC 
sw 
0.1 1 1 
3 3 
MC, BC+RC, 
LCne+LCsw 
0.45 1 2 
4 4 
MC, BC, RC, 
LCne+LCsw 
0.2 3 1 
5 5 
MC, BC, RC, 
Lcne, LCsw 
0.1 5 
6 6 
MC, BC, RC, 
Lcne, LCsw, ? 
0.025 6 
7 7 
MC, BC, RC, 
Lcne, LCsw, 
?, ? 
0.025 7 
DTN: MO0002PVHA0082.000 [148234] 
Source: CRWMS M&O (1996 [100116], Appendix E, Table BC-3, p. BC-39) 
NOTE: * LW = Lathrop Wells; HC = Hidden Cone; LBP = Little Black Peak; MC = Makani 
Cone; BC = Black Cone; RC = Red Cone; Lcne = Little Cones North East; LCsw = 
Little Cones southwest, ? undetected. A + indicates eruptive centers considered to be 
part of a single volcanic event. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-7 September 2003 
Table III-3. Assessments from George Thompsons Volcanic Hazard Model 
Number of Events with nEC = Volcanic 
Center Scenario 
Number of 
Events* Probability 1 2 3 4 5 
Lathrop Wells 1 1 
LW 
0.75 1 
2 2 
LW, LW 
0.09 2 
3 3 
LW, LW, LW 
0.08 3 
4 4 
LW, LW, LW, 
LW 
0.08 4 
Sleeping Butte 1 1 
LBP+HC 
0.35 1 
2 2 
LBP, HC 
0.65 2 
Crater Flat 1 1 
MC+BC+RC+ 
LCne+LCsw 
0.2 1 
2 2 
MC, BC+RC+ 
LCne+LCsw 
0.15 1 1 
3 3 
MC, BC+RC, 
LCne+LCsw 
0.1 1 2 
4 4 
MC, BC, RC, 
LCne+LCsw 
0.5 3 1 
5 5 
MC, BC, RC, 
Lcne, LCsw 
0.05 5 
DTN: MO0002PVHA0082.000 [148234] 
Source: CRWMS M&O (1996 [100116], Appendix E, Table GT-1, p. GT-11) 
NOTE: * LW = Lathrop Wells; HC = Hidden Cone; LBP = Little Black Peak; MC = Makani 
Cone; BC = Black Cone; RC = Red Cone; Lcne = Little Cones North East; LCsw = 
Little Cones southwest, ? undetected. A + indicates eruptive centers considered to 
be part of a single volcanic event. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-8 September 2003 
Table III-4. Assessments from George Walkers Volcanic Hazard Model 
Number of Events with nEC = 
Volcanic 
Center Scenario 
Number of 
Events* Probability 1 2 3 4 5 
Lathrop Wells 1 1 
LW 
0.9 1 
2 2 
LW, LW 
0.07 2 
3 3 
LW, LW, LW 
0.02 3 
4 4 
LW, LW, LW, LW 
0.01 4 
Sleeping Butte 1 1 
LBP+HC 
0.4 1 
2 2 
LBP, HC 
0.6 2 
Crater Flat 1 1 
MC+BC+RC+ 
LCne+LCsw 
0.1 1 
3 3 
MC, BC+RC, 
LCne+LCsw 
0.35 1 2 
4 4 
MC, BC, RC, 
LCne+LCsw 
0.55 3 1 
DTN: MO0002PVHA0082.000 [148234] 
Source: CRWMS M&O (1996 [100116], Appendix E, Table GW-1, p. GW-11). 
NOTE: * LW = Lathrop Wells; HC = Hidden Cone; LBP = Little Black Peak; MC = Makani 
Cone; BC=Black Cone; RC = Red Cone; Lcne = Little Cones North East; LCsw = 
Little Cones southwest, ? undetected. A + indicates eruptive centers considered to 
be part of a single volcanic event. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-9 September 2003 
Table III-5. Assessments from Mel Kuntzs Volcanic Hazard Model 
Number of Events with nEC = Volcanic 
Center Scenario 
Number of 
Events * Probability 1 2 3 4 5 
Lathrop Wells 1 1 
LW 
0.95 1 
2 2 
LW, LW 
0.03 2 
3 3 
LW, LW, LW 
0.019 3 
4 4 
LW, LW, LW, 
LW 
0.001 4 
Sleeping 
Butte 
1 1 
LBP+HC 
0.6 1 
2 2 
LBP, HC 
0.3 2 
3 3 
LBP, HC, ? 
0.1 3 
Crater Flat 1 1 
MC+BC+RC+ 
LCne+LCsw 
0.6 1 
2 2 
MC, BC+RC+ 
LCne+LCsw 
0.3 1 1 
3 3 
MC, BC+RC, 
LCne+LCsw 
0.05 1 2 
4 4 
MC, BC, RC, 
LCne+LCsw 
0.05 3 1 
DTN: MO0002PVHA0082.000 [148234] 
Source: CRWMS M&O (1996 [100116], Appendix E, Table MK-1, p. MK-18). 
NOTE: * LW = Lathrop Wells; HC = Hidden Cone; LBP = Little Black Peak; M = Makani Cone; 
BC = Black Cone; RC = Red Cone; Lcne = Little Cones North East; LCsw = Little 
Cones southwest, ? undetected. A + indicates eruptive centers considered to be part 
of a single volcanic event. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-10 September 2003 
Table III-6. Assessments from Michael Sheridans Volcanic Hazard Model 
Number of Events with nEC = Volcanic 
Center Scenario 
Number of 
Events * Probability 1 2 3 4 5 
Lathrop Wells 1 1 
LW 
0.9 1 
2 2 
LW, LW 
0.1 2 
Sleeping Butte 1 1 
LBP+HC 
0.67 1 
2 2 
LBP, HC 
0.33 2 
Crater Flat 1 1 
MC+BC+RC+ 
LCne+LCsw 
0.7 1 
2 2 
MC, BC+RC+ 
LCne+LCsw 
0.2 1 4 
3 3 
MC, BC+RC, 
LCne+LCsw 
0.1 1 2 2 
DTN: MO0002PVHA0082.000 [148234] 
Source: CRWMS M&O (1996 [100116], Appendix E, Table MS-1, p. MS-16 and from text on 
pages MS-6 to MS-7). 
NOTE: * LW = Lathrop Wells; HC = Hidden Cone; LBP = Little Black Peak; MC = Makani 
Cone; BC = Black Cone; RC = Red Cone; Lcne = Little Cones North East; LCsw = 
Little Cones southwest, ? undetected. A + indicates eruptive centers considered to 
be part of a single volcanic event. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-11 September 2003 
Table III-7. Assessments from Richard Carlsons Volcanic Hazard Model 
Number of Events with nEC = Volcanic 
Center Scenario 
Number of 
Events * Probability 1 2 3 4 5 
Lathrop Wells 1 1 
LW 
0.95 1 
2 2 
LW, LW 
0.05 2 
Sleeping 
Butte 
1 1 
LBP+HC 
0.7 1 
2 2 
LBP, HC 
0.2 2 
3 3 
LBP, HC, ? 
0.1 3 
Crater Flat 1 1 
MC+BC+RC+ 
LCne+LCsw 
0.6 1 
3 3 
MC, BC+RC, 
LCne+LCsw 
0.3 1 2 
5 5 
MC, BC, RC, 
Lcne, LCsw 
0.01 5 
DTN: MO0002PVHA0082.000 [148234] 
Source: CRWMS M&O (1996 [100116], Appendix E, Table RC-1, p. RC-16). 
NOTE: * LW = Lathrop Wells; HC = Hidden Cone; LBP = Little Black Peak; MC = Makani 
Cone; BC = Black Cone; RC = Red Cone; Lcne = Little Cones North East; LCsw = 
Little Cones southwest, ? undetected. A + indicates eruptive centers considered to 
be part of a single volcanic event. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-12 September 2003 
Table III-8. Assessments from Richard Fishers Volcanic Hazard Model 
Number of Events with nEC = Volcanic 
Center Scenario 
Number of 
Events * 
Probabilit 
y 1 2 3 4 5 
Lathrop Wells 1 1 
LW 
0.6 1 
2 2 
LW, LW 
0.3 2 
3 3 0.05 3 
4 4 0.05 4 
Sleeping Butte 1 1 
LBP+HC 
0.7 1 
2 2 
LBP, HC 
0.25 2 
3 3 
LBP, HC, HC 
0.05 3 
Crater Flat 1 1 
MC+BC+RC+ 
LCne+LCsw 
0.8 1 
2 2 
MC+BC, 
RC+LCne+LCs 
w 
0.05 1 1 
3 3 
MC, BC+RC, 
LCne+LCsw 
0.05 1 2 
4 4 
MC, BC, RC, 
LCne+LCsw 
0.1 3 1 
DTN: MO0002PVHA0082.000 [148234] 
Source: CRWMS M&O (1996 [100116], Appendix E, Table RF-1, p. RF-12). 
NOTE: * LW = Lathrop Wells; HC = Hidden Cone; LBP = Little Black Peak; MC = Makani 
Cone; BC = Black Cone; RC = Red Cone; LCne = Little Cones North East; LCsw = 
Little Cones southwest, ? undetected. A + indicates eruptive centers considered to 
be part of a single volcanic event. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-13 September 2003 
Table III-9. Assessments from Wendell Duffields Volcanic Hazard Model 
Number of Events with nEC = Volcanic 
Center Scenario 
Number of 
Events* Probability 1 2 3 4 5 
Lathrop Wells 1 1 
LW 
0.9 1 
2 2 
LW, LW 
0.1 2 
Sleeping 
Butte 
1 1 
LBP+HC 
0.05 1 
2 2 
LBP, HC 
0.95 2 
Crater Flat 1 1 
MC+BC+RC+ 
LCne+LCsw 
0.07 1 
2 2 
MC+BC+RC, 
LCne+LCsw 
0.14 1 1 
3 3 
MC, BC+RC, 
LCne+LCsw 
0.26 1 2 
4 4 
MC, BC, RC, 
LCne+LCsw 
0.34 3 1 
5 5 
MC, BC, RC, 
Lcne, LCsw 
0.19 5 
DTN: MO0002PVHA0082.000 [148234] 
Source: CRWMS M&O (1996 [100116], Appendix E, Table WD-1, pp. WD-11 and page 
WD-5). 
NOTE: * LW = Lathrop Wells; HC = Hidden Cone; LBP = Little Black Peak; MC = Makani 
Cone; BC = Black Cone; RC = Red Cone; Lcne = Little Cones North East; LCsw = 
Little Cones southwest, ? undetected. A + indicates eruptive centers considered to 
be part of a single volcanic event. 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-14 September 2003 
Table III-10. Assessments from William Hacketts Volcanic Hazard Model 
Number of Events with nEC = Volcanic 
Center Scenario 
Number of 
Events* Probability 1 2 3 4 5 
Lathrop Wells 1 1 
LW 
0.4 1 
2 2 
LW, LW 
0.1 2 
3 3 
LW, LW, LW 
0.4 3 
4 4 
LW, LW, LW, 
LW 
0.05 4 
5 5 
LW, LW, LW, 
LW, LW 
0.05 5 
Sleeping 
Butte 
1 1 
LBP+HC 
0.4 1 
2 2 
LBP, HC 
0.5 2 
3 3 
LBP, HC, ? 
0.1 3 
Crater Flat 1 1 
MC+BC+RC+ 
LCne+LCsw 
0.1 1 
2 2 
MC+BC+RC, 
LCne+LCsw 
0.3 1 1 
3 3 
MC, BC+RC, 
LCne+LCsw 
0.4 1 2 
4 4 
MC, BC, RC, 
LCne+LCsw 
0.1 3 1 
5 5 
MC, BC, RC, 
Lcne, LCsw 
0.05 5 
6 6 
MC, BC, RC, 
Lcne, LCsw, ? 
0.05 6 
DTN: MO0002PVHA0082.000 [148234] 
Source: CRWMS M&O (1996 [100116], Appendix E, Table WH-1, pp. WH-16). 
NOTE: * LW = Lathrop Wells; HC = Hidden Cone; LBP = Little Black Peak; MC = Makani 
Cone; BC = Black Cone; RC = Red Cone; Lcne = Little Cones North East; LCsw = 
Little Cones southwest, ? undetected. A + indicates eruptive centers considered to 
be part of a single volcanic event. 
The locations of the Quaternary volcanoes are listed in Table III-11. These values were used in 
the PVHA calculation (CRWMS M&O 1996 [100116]) and were taken from Connor and Hill 
(1995 [102646]). 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-15 September 2003 
Table III-11. Volcano Locations 
UTM East (km) UTM North (km) Volcano 
543.780 4060.380 Lathrop Wells 
523.230 4112.530 Hidden Cone 
522.130 4110.340 Little Black Peak Cone 
540.330 4079.130 Makani Cone (North Cone) 
538.840 4073.990 Black Cone 
537.450 4071.470 Red Cone 
535.500 4069.490 Little Cone northwest 
535.131 4069.220 Little Cone southeast 
DTN: MO0002PVHA0082.000 [148234] 
The calculation of the distribution for the number of eruptive centers per volcanic event and the 
average spacing between eruptive centers was performed using the software routine NECPDS 
V1.0 (STN: 10272-1.0-00 [148555]). The data in Tables III-1 through III-11 were used to 
create the following input files. The resulting output files are listed after each input file. 
**** File: AMNECPDS.IN **** 
vxy.dat 
amnecpds.out 
AM no ec on dikes at LW, SB, NWCF 
4 0.3 0.2 0.4 0.1 
1 1 1 
2 1 1 1 1 
3 1 1 1 1 1 1 
4 1 1 1 1 1 1 1 1 
3 0.05 0.8 0.15 
1 2 2 3 
2 1 2 1 3 
3 1 2 1 3 1 3 
5 0.9 0.05 0.025 0.015 0.01 
1 5 4 5 6 7 8 
2 4 5 6 7 8 1 4 
3 2 7 8 2 5 6 1 4 
4 2 7 8 1 5 1 6 1 4 
5 1 4 1 5 1 6 1 7 1 8 
q 
**** File: AMNECPDS.OUT **** 
AM no ec on dikes at LW, SB, NWCF 
NEC 1 2 3 4 5 
0.797067 0.020689 0.000000 0.008057 0.174188 
average spacing = 2.69 
**** File: BCNECPDS.IN **** 
vxy.dat 
bcnecpds.out 
BC no ec on dikes at LW, SB, NWCF 
4 0.9 0.06 0.03 0.01 
1 1 1 
2 1 1 1 1 
3 1 1 1 1 1 1 
4 1 1 1 1 1 1 1 1 
3 0.35 0.45 0.2 
1 2 2 3 
2 1 2 1 3 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-16 September 2003 
3 1 2 1 3 1 3 
7 0.1 0.1 0.45 0.2 0.1 0.025 0.025 
1 5 4 5 6 7 8 
2 3 6 7 8 2 4 5 
3 2 7 8 2 5 6 1 4 
4 2 7 8 1 4 1 5 1 6 
5 1 4 1 5 1 6 1 7 1 8 
6 1 4 1 5 1 6 1 7 1 8 1 8 
7 1 4 1 5 1 6 1 7 1 8 1 8 1 8 
q 
**** File: BCNECPDS.OUT **** 
BC no ec on dikes at LW, SB, NWCF 
NEC 1 2 3 4 5 
0.681609 0.271645 0.020588 0.000000 0.026158 
average spacing = 1.87 
**** File: GTNECPDS.IN **** 
vxy.dat 
GTnecpds.out 
GT no ec on dikes at LW, SB, NWCF 
4 0.75 0.09 0.08 0.08 
1 1 1 
2 1 1 1 1 
3 1 1 1 1 1 1 
4 1 1 1 1 1 1 1 1 
2 0.35 0.65 
1 2 2 3 
2 1 2 1 3 
5 0.2 0.15 0.1 0.5 0.05 
1 5 4 5 6 7 8 
2 4 5 6 7 8 1 4 
3 2 7 8 2 5 6 1 4 
4 2 7 8 1 5 1 6 1 4 
5 1 4 1 5 1 6 1 7 1 8 
q 
**** File: GTNECPDS.OUT **** 
GT no ec on dikes at LW, SB, NWCF 
NEC 1 2 3 4 5 
0.744308 0.174364 0.000000 0.030266 0.051062 
average spacing = 1.53 
**** File: GWNECPDS.IN **** 
vxy.dat 
gwnecpds.out 
GW no ec on dikes at LW, SB, NWCF 
4 0.9 0.07 0.02 0.01 
1 1 1 
2 1 1 1 1 
3 1 1 1 1 1 1 
4 1 1 1 1 1 1 1 1 
2 0.4 0.6 
1 2 2 3 
2 1 2 1 3 
3 0.1 0.35 0.55 
1 5 4 5 6 7 8 
3 2 7 8 2 5 6 1 4 
4 2 7 8 1 4 1 5 1 6 
q 
**** File: GWNECPDS.OUT **** 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-17 September 2003 
GW no ec on dikes at LW, SB, NWCF 
NEC 1 2 3 4 5 
0.690211 0.282237 0.000000 0.000000 0.027552 
average spacing = 1.36 
**** File: MKNECPDS.IN **** 
vxy.dat 
MKnecpds.out 
MK no ec on dikes at LW, SB, NWCF 
4 0.95 0.03 0.019 0.001 
1 1 1 
2 1 1 1 1 
3 1 1 1 1 1 1 
4 1 1 1 1 1 1 1 1 
3 0.6 0.3 0.1 
1 2 2 3 
2 1 2 1 3 
3 1 2 1 3 1 3 
4 0.6 0.3 0.05 0.05 
1 5 4 5 6 7 8 
2 4 5 6 7 8 1 4 
3 2 7 8 2 5 6 1 4 
4 2 7 8 1 4 1 5 1 6 
q 
**** File: MKNECPDS.OUT **** 
MK no ec on dikes at LW, SB, NWCF 
NEC 1 2 3 4 5 
0.559011 0.199381 0.000000 0.067184 0.174424 
average spacing = 2.40 
**** File: MSNECPDS.IN **** 
vxy.dat 
MSnecpds.out 
MS no ec on dikes at LW, SB, NWCF 
2 0.9 0.1 
1 1 1 
2 1 1 1 1 
2 0.67 0.33 
1 2 2 3 
2 1 2 1 3 
3 0.7 0.2 0.1 
1 5 4 5 6 7 8 
2 4 5 6 7 8 1 4 
3 2 7 8 2 5 6 1 4 
q 
**** File: MSNECPDS.OUT **** 
MS no ec on dikes at LW, SB, NWCF 
NEC 1 2 3 4 5 
0.509542 0.235628 0.000000 0.045810 0.209020 
average spacing = 2.49 
**** File: RCNECPDS.IN **** 
vxy.dat 
RCnecpds.out 
RC no ec on dikes at LW, SB, NWCF 
2 0.95 0.05 
1 1 1 
2 1 1 1 1 
3 0.7 0.2 0.1 
1 2 2 3 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-18 September 2003 
2 1 2 1 3 
3 1 2 1 3 1 3 
3 0.6 0.3 0.1 
1 5 4 5 6 7 8 
3 2 7 8 2 5 6 1 4 
5 1 4 1 5 1 6 1 7 1 8 
q 
**** File: RCNECPDS.OUT **** 
RC no ec on dikes at LW, SB, NWCF 
NEC 1 2 3 4 5 
0.518637 0.301513 0.000000 0.000000 0.179850 
average spacing = 2.40 
**** File: RFNECPDS.IN **** 
vxy.dat 
RFnecpds.out 
RF no ec on dikes at LW, SB, NWCF 
4 0.6 0.3 0.05 0.05 
1 1 1 
2 1 1 1 1 
3 1 1 1 1 1 1 
4 1 1 1 1 1 1 1 1 
3 0.7 0.25 0.05 
1 2 2 3 
2 1 2 1 3 
3 1 2 1 3 1 3 
4 0.8 0.05 0.05 0.1 
1 5 4 5 6 7 8 
2 3 6 7 8 2 4 5 
3 2 7 8 2 5 6 1 4 
4 2 7 8 1 4 1 5 1 6 
q 
**** File: RFNECPDS.OUT **** 
RF no ec on dikes at LW, SB, NWCF 
NEC 1 2 3 4 5 
0.540624 0.232107 0.010571 0.000000 0.216698 
average spacing = 2.51 
**** File: WDNECPDS.IN **** 
vxy.dat 
WDnecpds.out 
WD no ec on dikes at LW, SB, NWCF 
2 0.9 0.1 
1 1 1 
2 1 1 1 1 
2 0.05 0.95 
1 2 2 3 
2 1 2 1 3 
5 0.07 0.14 0.26 0.34 0.19 
1 5 4 5 6 7 8 
2 2 7 8 3 4 5 6 
3 2 7 8 2 5 6 1 4 
4 2 7 8 1 4 1 5 1 6 
5 1 4 1 5 1 6 1 7 1 8 
q 
**** File: WDNECPDS.OUT **** 
WD no ec on dikes at LW, SB, NWCF 
NEC 1 2 3 4 5 
0.782655 0.172043 0.027872 0.000000 0.017430 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-19 September 2003 
average spacing = 1.40 
**** File: WHNECPDS.IN **** 
vxy.dat 
WHnecpds.out 
WH no ec on dikes at LW, SB, NWCF 
5 0.4 0.1 0.4 0.05 0.05 
1 1 1 
2 1 1 1 1 
3 1 1 1 1 1 1 
4 1 1 1 1 1 1 1 1 
5 1 1 1 1 1 1 1 1 1 1 
3 0.4 0.5 0.1 
1 2 2 3 
2 1 2 1 3 
3 1 2 1 3 1 3 
6 0.1 0.3 0.4 0.1 0.05 0.05 
1 5 4 5 6 7 8 
2 3 4 5 6 2 7 8 
3 2 5 6 2 7 8 1 4 
4 2 7 8 1 4 1 5 1 6 
5 1 4 1 5 1 6 1 7 1 8 
6 1 4 1 5 1 6 1 7 1 8 1 8 
q 
**** File: WHNECPDS.OUT **** 
WH no ec on dikes at LW, SB, NWCF 
NEC 1 2 3 4 5 
0.668581 0.256513 0.053095 0.000000 0.021812 
average spacing = 1.97 
The distributions for nEC for each expert are plotted in Figure III-1. The expected value for the 
average spacing between eruptive centers computed from each PVHA experts hazard model is 
listed in Table III-12. 
Table III-12. Summary of Expected Average Spacing Between Eruptive Centers Calculation 
Results 
PVHA Expert 
Expected Average Spacing 
Between Eruptive Centers (km) 
Alex McBirney (AM) 2.7 
Bruce Crowe (BC) 1.9 
George Thompson (GT) 1.5 
George Walker (GW) 1.4 
Mel Kuntz (MK) 2.4 
Michael Sheridan (MS) 2.5 
Richard Carlson (RC) 2.4 
Richard Fisher (RF) 2.5 
Wendell Duffield (WD) 1.4 
William Hackett (WH) 2.0 
Output Data. DTN: LA0009FP831811.001 [164712] 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-20 September 2003 
0 
0.1 
0.2 
0.3 
0.4 
0.5 
0.6 
0.7 
0.8 
0.9 
1 2 3 4 5 
Number of Eruptive Centers per Volcanic Event 
Probability 
AM 
BC 
GT 
GW 
MK 
MS 
RC 
RF 
WD 
WH 
Output Data. DTN: LA0009FP831811.001 [164712] 
NOTE: The two-letter code indicates the PVHA experts initials from Table III-12. 
Figure III-1. Distributions for Number of Eruptive Centers per Volcanic Event, nEC, Derived from the 
Probabilistic Volcanic Hazard Analysis Experts Interpretations 
Computed Empirical Distributions for Average Spacing of Eruptive Centers 
The calculation of the empirical distribution for the average spacing between eruptive centers 
was performed using the software routine NECPDS V1.1 (STN: 10272-1.1-00 [148555]). The 
software routine uses the same input files listed above and outputs all of the same data plus the 
empirical distribution for average spacing of eruptive centers. The resulting output files are 
listed below. 
**** File: AMNECPDS.OUT **** 
AM no ec on dikes at LW, SB, NWCF 
NEC 1 2 3 4 5 
0.797067 0.020689 0.000000 0.008057 0.174188 
average spacing = 2.69 
Average spacing distribution 
5 0.46 0.0272 2.01 0.0492 2.45 0.0253 2.80 0.8859 2.88 0.0124 
average spacing from distribution = 2.69 
**** File: BCNECPDS.OUT **** 
BC no ec on dikes at LW, SB, NWCF 
NEC 1 2 3 4 5 
0.681609 0.271645 0.020588 0.000000 0.026158 
average spacing = 1.87 
Average spacing distribution 
6 0.46 0.4030 1.62 0.0489 2.45 0.1874 2.80 0.0914 2.88 0.2202 5.35 0.0489 
average spacing from distribution = 1.88 
**** File: GTNECPDS.OUT **** 
GT no ec on dikes at LW, SB, NWCF 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-21 September 2003 
NEC 1 2 3 4 5 
0.744308 0.174364 0.000000 0.030266 0.051062 
average spacing = 1.53 
Average spacing distribution 
5 0.46 0.4720 2.01 0.1279 2.45 0.1839 2.80 0.1705 2.88 0.0457 
average spacing from distribution = 1.53 
**** File: GWNECPDS.OUT **** 
GW no ec on dikes at LW, SB, NWCF 
NEC 1 2 3 4 5 
0.690211 0.282237 0.000000 0.000000 0.027552 
average spacing = 1.36 
Average spacing distribution 
4 0.46 0.5917 2.45 0.1767 2.80 0.0800 2.88 0.1517 
average spacing from distribution = 1.37 
**** File: MKNECPDS.OUT **** 
MK no ec on dikes at LW, SB, NWCF 
NEC 1 2 3 4 5 
0.559011 0.199381 0.000000 0.067184 0.174424 
average spacing = 2.40 
Average spacing distribution 
5 0.46 0.0550 2.01 0.2100 2.45 0.2950 2.80 0.4200 2.88 0.0200 
average spacing from distribution = 2.40 
**** File: MSNECPDS.OUT **** 
MS no ec on dikes at LW, SB, NWCF 
NEC 1 2 3 4 5 
0.509542 0.235628 0.000000 0.045810 0.209020 
average spacing = 2.49 
Average spacing distribution 
5 0.46 0.0388 2.01 0.1330 2.45 0.3238 2.80 0.4655 2.88 0.0388 
average spacing from distribution = 2.49 
**** File: RCNECPDS.OUT **** 
RC no ec on dikes at LW, SB, NWCF 
NEC 1 2 3 4 5 
0.518637 0.301513 0.000000 0.000000 0.179850 
average spacing = 2.40 
Average spacing distribution 
4 0.46 0.1186 2.45 0.3608 2.80 0.4021 2.88 0.1186 
average spacing from distribution = 2.41 
**** File: RFNECPDS.OUT **** 
RF no ec on dikes at LW, SB, NWCF 
NEC 1 2 3 4 5 
0.540624 0.232107 0.010571 0.000000 0.216698 
average spacing = 2.51 
Average spacing distribution 
6 0.46 0.0842 1.62 0.0192 2.45 0.3383 2.80 0.5200 2.88 0.0192 5.35 0.0192 
average spacing from distribution = 2.51 
**** File: WDNECPDS.OUT **** 
WD no ec on dikes at LW, SB, NWCF 
NEC 1 2 3 4 5 
0.782655 0.172043 0.027872 0.000000 0.017430 
average spacing = 1.40 
Average spacing distribution 
5 0.46 0.6445 2.45 0.0322 2.80 0.0833 2.88 0.1560 4.09 0.0840 
average spacing from distribution = 1.40 
**** File: WHNECPDS.OUT **** 

Characterize Framework for Igneous Activity at Yucca Mountain, Nevada 
ANL-MGR-GS-000001 REV 01 III-22 September 2003 
WH no ec on dikes at LW, SB, NWCF 
NEC 1 2 3 4 5 
0.668581 0.256513 0.053095 0.000000 0.021812 
average spacing = 1.97 
Average spacing distribution 
5 0.46 0.4078 2.45 0.1844 2.80 0.0851 2.88 0.1844 4.09 0.1383 
average spacing from distribution = 1.97 
The empirical distributions for the average spacing between eruptive centers computed from 
each PVHA experts hazard model are listed in Table III-13. 
Table III-13. Empirical Distribution for Average Spacing Between Eruptive Centers Calculation Results 
PVHA Expert 
Empirical Distribution for Average Spacing 
between Eruptive Centers (km) 
Alex McBirney (AM) 0.46 (0.0272), 2.01 (0.0492 ), 2.45 (0.0253 ), 
2.80 (0.8859 ), 2.88 (0.0124) 
Bruce Crowe (BC) 0.46 (0.4031), 1.62 (0.0489), 2.45 (0.1874), 
2.80 (0.0914), 2.88 (0.2203), 5.35 (0.0489) 
George Thompson (GT) 0.46 (0.4720), 2.01 (0.1279), 2.45 (0.1839), 
2.80 (0.1705), 2.88 (0.0457) 
George Walker (GW) 0.46 (0.5916), 2.45 (0.1767), 2.80 (0.0800), 
2.88 (0.1517) 
Mel Kuntz (MK) 0.46 (0.0550), 2.01 (0.2100), 2.45 (0.2950), 
2.80 (0.4200), 2.88 (0.0200) 
Michael Sheridan (MS) 0.46 (0.0388), 2.01 (0.1330), 2.45 (0.3238), 
2.80 (0.4656), 2.88 (0.0388) 
Richard Carlson (RC) 0.46 (0.1186), 2.45 (0.3608), 2.80 (0.4020), 
2.88 (0.1186) 
Richard Fisher (RF) 0.46 (0.0842), 1.62 (0.0192), 2.45 (0.3383), 
2.80 (0.5199), 2.88 (0.0192), 5.35 (0.0192) 
Wendell Duffield (WD) 0.46 (0.6445), 2.45 (0.0322), 2.80 (0.0833), 
2.88 (0.1560), 4.09 (0.0840) 
William Hackett (WH) 0.46 (0.4078), 2.45 (0.1844), 2.80 (0.0851), 
2.88 (0.1844), 4.09 (0.1383) 
Output Data. DTN: LA0009FP831811.002 [164714] 
NOTE: The values in ( ) are the empirical probability for the preceding 
value of average spacing.