Catalog of Earthquake Hypocenters at Alaskan 

Volcanoes: January 1 through December 31, 2011

Data Series 730

U.S. Department of the Interior

U.S. Geological Survey

Catalog of Earthquake Hypocenters at 

Alaskan Volcanoes: January 1 through 

December 31, 2011

By James P. Dixon, U.S. Geological Survey, Scott D. Stihler, University of Alaska 

Fairbanks, John A. Power, U.S. Geological Survey, and Cheryl K. Searcy, U.S. 

Geological Survey

Data Series 730

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2012

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Suggested citation:

Dixon, J.P., Stihler, S.D., Power, J.A., and Searcy, C.K., 2012, Catalog of earthquake hypocenters at Alaskan Volcanoes: 

January 1 through December 31, 2011: U.S. Geological Survey Data Series 730, 82 p.
iii

Contents

Abstract ..........................................................................................................................................................1

Introduction.....................................................................................................................................................1

Instrumentation..............................................................................................................................................1

Data Acquisition and Processing................................................................................................................7

Seismic Velocity Models ..............................................................................................................................8

Seismicity........................................................................................................................................................9

Summary........................................................................................................................................................11

Acknowledgments.......................................................................................................................................11

References Cited..........................................................................................................................................11

Appendix A. Maps of Monitored Volcanoes with Earthquake Hypocenters Calculated in 2011....13

Appendix B. Parameters for Alaska Volcano Observatory Seismograph Stations in 2011 .............43

Appendix C. Locations of the Alaska Volcano Observatory Seismograph Stations in 2011............49

Appendix D. Operational Status for Alaska Volcano Observatory Stations in 2011 .........................65

Appendix E. Seismic Velocity Models Used in Locating the Earthquakes in 2011............................71

Appendix F. Location of Volcanic Zones Modeled Using Multiple Cylinders.....................................77

Appendix G. Previous Alaska Volcano Observatory Earthquake Catalogs........................................79

Appendix H. Selected Papers Published in 2011 Using Alaska Volcano Observatory Data ...........81

Figures

Figure 1. Location of volcanoes mentioned in this report.......................................... 2

Figure 2. Number of AVO seismograph stations by type and year .............................. 2

Figure 4. Log-log plot of representative displacement response curves for the AVO

broadband stations using a CMG-6TD (black) or CMG-40T (red) seismometer...... 5

Figure 3. Log-log plot of representative displacement response curves for AVO

short-period stations using a L4 (black), S13 (red), or L22 (green) seismometer ... 5

Figure 5. Graph showing estimate of the network operational status ........................... 6

Figure 6. Graph showing comparison of earthquakes, by magnitude (ML), that are

uniquely located by AVO staff (green) and those located independently by both

AVO and AEIC staff (yellow) in 2011 ...................................................... 8

Figure 7. Graph showing number of earthquakes located per year in the AVO catalog

(black line) and number of monitored volcanoes per year (green bars) ............ 9

Tables

Table 1. Number of permanent AVO seismograph stations by type and network in 2011 ... 3

Table 2. Number of AVO seismograph stations by type and year .............................. 4

Table 3. Volcano subnetwork designators ......................................................... 7

Table 4. Alaska Volcano Observatory event description codes ................................. 7

Table 5. Number of earthquakes located for each seismograph subnetwork in 2011 

within 20 km of the volcanic centers in each subnetwork ........................... 10

Table 6. Number of earthquakes located per year in the AVO earthquake catalog ......... 11
iv

Conversion Factors and Datum

Conversion Factors 

Multiply By To obtain

kilometer (km) 0.6214 mile (mi)

meter (m) 3.281 foot (ft) 

Datum

Horizontal coordinate information is referenced to North American Datum of 1927 (NAD 27). 
Abstract 

Between January 1 and December 31, 2011, the Alaska 

Volcano Observatory (AVO) located 4,364 earthquakes, 

of which 3,651 occurred within 20 kilometers of the 33 

volcanoes with seismograph subnetworks. There was no 

significant seismic activity above background levels in 2011 

at these instrumented volcanic centers. This catalog includes 

locations, magnitudes, and statistics of the earthquakes located 

in 2011 with the station parameters, velocity models, and other 

files used to locate these earthquakes. 

Introduction

The Alaska Volcano Observatory (AVO), established 

in 1988 as a cooperative program of the U.S. Geological 

Survey, the Geophysical Institute at the University of Alaska 

Fairbanks, and the Alaska Division of Geological and 

Geophysical Surveys, monitors historically active volcanoes 

in Alaska (fig. 1). The primary objectives of the AVO seismic 

program are the real-time seismic monitoring of active and 

potentially hazardous Alaskan volcanoes and the investigation 

of seismic processes associated with active volcanism. 

This catalog describes the (1) location of seismic 

instrumentation deployed in the field; (2) earthquake 

detection, recording, analysis, and data archival systems; 

(3) seismic velocity models used for earthquake locations; 

and (4) summary of earthquakes located in 2011. A summary 

of earthquake origin times, hypocenters, magnitudes, phase 

arrival times, location quality statistics, daily station usage 

statistics, all files used to determine the earthquake locations 

in 2011, and metadata file in the format of a dataless Standard 

for the Exchange of Earthquake Data (SEED) volume (SEED 

Manual, 2010) for the AVO seismograph network are included 

in a data supplement to this report.

Instrumentation

The permanent AVO seismograph network is composed 

of 24 subnetworks each with 4 to 20 seismograph stations and 

10 regional seismograph stations for a total of 201 stations 

(tables 1 and 2; fig. 2). Six broadband seismograph stations 

were added to the AVO seismograph networks in 2011. Four 

were co-located with short-period sensors (AKS, NCT, RED, 

and MSW), one was added to the Spurr subnetwork (SPNN), 

and one to the Redoubt subnetwork (RDSO). Seismic station 

AUSE was relocated and renamed AUJK. Seismograph station 

SPNW was removed.

Thirty-three of the 52 historically active volcanic 

centers in Alaska (Schaefer and others, 2009) were monitored 

with a seismograph network in 2011. Three of the 33 were 

not included on the formal list of permanently monitored 

volcanoes in the AVO weekly update at the end of the year. To 

be included on the monitored list in the AVO weekly update, 

the seismic subnetwork on the volcano must be in place long 

enough to determine the background seismicity level, typically 

6 months, and have had no prolonged station outages. Loss of 

data due to telemetry outages since their installation in 2005 

has prevented Little Sitkin and Mount Cerberus, the active 

vent on Semisopochnoi Island, from being added to list of 

permanently monitored volcanoes. Korovin was delisted in 

October 2011 and was not on the formal list of permanently 

monitored volcanoes on December 31, 2011. 

The single-component short-period seismograph stations 

were equipped with either Mark Products L4 or TeledyneGeotech S13 seismometers with a natural period of 1 Hz. 

AVO also operated three-component, short-period instruments 

during 2011. Such sites used Mark Products L22, L4, or S13 

seismometers. The L22 seismometer has a natural period of 

2 Hz. Broadband stations were operated with either a Guralp 

CMG-40T seismometer (frequency range: 0.033–50 Hz), 

Guralp CMG-6TD seismometer (frequency range: 0.033–

50 Hz), or Nanometrics Trillium 40 seismometer (frequency 

range: 0.025–50 Hz). The Augustine strong motion station 

(AU22) used a REFTEK 130-ANSS/02 strong motion sensor 

(frequency range: DC–500 Hz). 

Catalog of Earthquake Hypocenters at Alaskan Volcanoes: 

January 1 through December 31, 2011

By James P. Dixon1, Scott D. Stihler2, John A. Power3, and Cheryl Searcy3

1

U.S. Geological Survey, Volcano Science Center, 903 Koyukuk Drive, Fairbanks, AK 99775.

2

 University of Alaska Fairbanks, Geophysical Institute, 903 Koyukuk Drive, Fairbanks, AK 99775.

3

 U.S. Geological Survey, Volcano Science Center, 4210 University Drive, Anchorage, AK 99508.
2 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure 1. Location of volcanoes mentioned in this report.

170 W 

178 E 

52 N 

56 N 

60 N 

64 N 

158 W 

150 W 

2 

1 

5 

4 

3 

7 8 

10 

12 9 

13 11 

14 

15 

16 

17 

19 

18 

20 

22 21 24 

23 25 

26 

30 31 32 

27 

34 

28

0 200 400 mi 

0 200 400 km 

 

BERING SEA 

Aleutian Islands 

Amchitka Is. 

Adak 

ALASKA 

GULF OF ALASKA 

PACIFIC OCEAN 

Anchorage 

1. Wrangell 

2. Spurr 

3. Redoubt 

4. Iliamna 

5. Augustine 

6. Fourpeaked 

 7. Snowy 

 8. Griggs 

 9. Katmai 

10. Novarupta 

11. Trident 

12. Mageik 

13. Martin 

14. Ugashik-Peulik 

15. Ukinrek Maars 

16. Aniakchak 

17. Veniaminof 

18. Pavlof 

19. Dutton 

20. Isanostski 

21. Shishaldin 

22. Fisher 

23. Westdahl 

24. Akutan 

25. Makushin 

26. Okmok 

27. Cleveland 

28. Korovin 

29. Great Sitkin 

30. Kanaga 

31. Tanaga 

32. Gareloi 

33. Cerberus 

34. Little Sitkin 

Unalaska 

Volcano monitored by real-time seismic network and

listed in the AVO weekly update at the end of 2011. 

Fairbanks 

Canada 

United

States

Akutan Cold Bay 

King Cove 

Homer 

Kenai 

Port Heiden 

King Salmon 

Tolsona 

162 W 

146 W 

178 W 

174 W 

 

Volcano monitored by real-time seismic network 

and was not listed in the AVO weekly update 

at the end of 2011. 

Volcano unmonitored by real-time seismic network 

and listed in an AVO weekly update in 2011. 

29 

Atka 

27 

34 33 34 

34 

6

Figure 2. Number of AVO seismograph stations by type and year.

1990 1995 2010 

0

50

100

150

200

250

Strong Motion

Broadband

Short-period,

three-component

Short-period,

single-component

Number of seismograph stations 

2000 2005 
 3

Subnetwork

Number of 

seismograph 

stations in each 

subnetwork

Number 

of station 

components 

in each 

subnetwork

Number 

of singlecomponent 

short-period 

stations

Number 

of threecomponent 

short-period 

stations

Number 

of threecomponent 

broadband 

stations

Number 

of threecomponent 

strong motion 

stations

Akutan 13 29 5 1 7 0

Aniakchak 6 8 5 1 0 0

Augustine 10 19 9 1 1 1

Cerberus 6 8 5 1 0 0

Dutton 5 5 5 0 0 0

Fourpeaked 4 7 4 0 0 0

Gareloi 6 8 5 1 0 0

Great Sitkin 6 8 5 1 0 0

Iliamna 6 8 5 1 0 0

Kanaga 6 6 6 0 0 0

Katmai 20 30 15 3 2 0

Korovin 7 9 6 1 0 0

Little Sitkin 4 6 3 1 0 0

Makushin 7 12 6 1 1 0

Okmok 13 21 9 0 4 0

Pavlof 7 9 6 1 0 0

Peulik 7 9 6 1 0 0

Redoubt 12 31 6 2 6 0

Shishaldin 7 11 5 1 1 0

Spurr 18 32 11 1 6 0

Tanaga 6 8 5 1 0 0

Veniaminof 9 9 9 0 0 0

Westdahl 6 8 5 1 0 0

Wrangell 4 6 3 1 0 0

Regional 

Stations

10 12 9 0 1 0

Totals 205 319 158 22 29 1

Table 1. Number of permanent AVO seismograph stations by type and network in 2011.
4 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Year

Number of 

stations in 

the AVO 

seismograph 

network

Number of 

components 

in the AVO 

seismograph 

network

Number 

of singlecomponent 

short-period 

stations

Number 

of threecomponent 

short-period 

stations

Number 

of threecomponent 

broadband 

stations

Number 

of threecomponent 

strong motion 

stations

1988 25 29 23 2 0 0

1989 28 32 26 2 0 0

1990 42 49 39 3 0 0

1991 36 42 33 3 0 0

1992 39 46 36 3 0 0

1993 44 51 41 3 0 0

1994 47 58 42 5 0 0

1995 57 67 52 5 0 0

1996 60 79 49 10 1 0

1997 93 125 83 12 2 0

1998 109 142 94 14 2 0

1999 122 156 106 14 2 0

2000 126 162 108 16 2 0

2001 139 177 120 17 3 0

2002 141 179 124 16 2 0

2003 161 217 135 18 9 0

2004 183 255 149 20 15 0

2005 189 266 151 23 15 0

2006 191 275 154 23 15 1

2007 194 281 154 22 17 1

2008 194 281 154 22 17 1

2009 197 291 155 22 19 1

2010 201 303 155 22 23 1

2011 205 319 158 22 29 1

Table 2. Number of AVO seismograph stations by type and year..

The majority of the short-period stations were digitized at 

100 samples per second (sps). The Cerberus and Little Sitkin 

subnetworks were recorded at 50 sps due to limitations in data 

rates using very small aperture terminal telemetry between the 

recording hubs located on Amchitka Island and Anchorage. 

Broadband stations were digitized at 50 sps with the exception 

of AUL, which is recorded at 100 sps. Each seismograph 

station is individually set to record above the noise level at 

each site and the range of calibration curves for short-period 

and broadband seismometers used in the AVO network are 

shown in figures 3 and 4. Calibration information for each 

station is found in a metadata file in the form of a dataless 

SEED volume included in a data supplement to this report.

Data from short-period seismograph stations were 

telemetered using voltage-controlled oscillators (VCOs) to 

transform the signals generated by the seismometer from 

a voltage to a frequency-modulated carrier suitable for 

transmission over a radio link or telephone circuit. AVO used 

VCOs developed by McChesney (1999) to modulate signals 

in the field with one exception. Seismograph station NCG 

used an A1VCO, a VCO that employs gain-ranging to increase 

the dymanic range that can be recorded. Gain-ranging VCOs 

are not needed with state of the art digitizers and are being 

replaced when possible. Signals were transmitted via UHF and 

VHF radio to communication hubs located in Adak, Akutan, 

Amchitka Island, Anchorage, Atka, Cold Bay, Homer, Kenai, 

King Cove, King Salmon, Port Heiden, Sourdough, Tolsona, 

and Unalaska (fig. 1). 
Instrumentation 5

Figure 3. Log-log plot of representative displacement response curves for AVO 

short-period stations using a L4 (black), S13 (red), or L22 (green) seismometer

Figure 4. Log-log plot of representative displacement response curves for the AVO broadband 

stations using a CMG-6TD (black) or CMG-40T (red) seismometer

40

0.10 1.00 10.00

160

100.00

20

60

100

140

120

Frequency (Hz)

80

System Amplitude Response (dB)

160

60

100

140

120

80

System Amplitude Response (dB)

180

0.01 0.10 1.00 10.00 100.00

Frequency (Hz)

40

20

60
6 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Data were then digitized at the Adak, Amchitka Island, 

Homer, Kenai, King Salmon, and Unalaska communication 

hubs and directed to AVO offices via high-speed digital 

circuits. From all other hubs (Akutan, Cold Bay, Port Heiden, 

Sourdough, and Tolsona), analog signals were relayed via 

leased telephone circuits to AVO offices in Anchorage or 

Fairbanks where the signals were subsequently digitized. Data 

from broadband seismograph stations were digitized at the 

station site and transmitted digitally using spread spectrum 

radios to communication hubs in Akutan, Anchorage, Homer, 

and King Salmon, and Unalaska. These data were forwarded 

to AVO offices in Fairbanks and Anchorage via high-speed 

digital circuits.

Fairbanks

Anchorage

Little Sitkin

Semisopochnoi

Gareloi

Tanaga

Kanaga

Great Sitkin

Korovin

Okmok

Makushin

Akutan

Westdahl

Fisher

Isonotski

Shishaldin

Dutton

Pavlof

Veniaminof

Aniakchak

Ukinrek

Peulik

Martin

Mageik

Novarupta

Trident

Griggs

Katmai

Snowy

Fourpeaked

Augustine

Iliamna

Redoubt

Spurr

Wrangell

4+ stations working

1-3 stations working

0 stations working

Outage Snapshot

Not monitored

Mar 2011

Jun 2011

Sept 2011

Dec 2011

Figure 5. Graph showing estimate of the network operational status

Earthquakes located in 2011 with the AVO seismograph 

network are shown in appendix A. Locations and descriptions 

for all AVO stations operated during 2011 are contained in 

appendix B. Maps showing the locations of stations with 

respect to individual volcanoes are contained in appendix C. 

Estimates of each station’s operational status for the catalog 

period are shown in figure 5 and appendix D. Other station 

information are available as part of the data supplement to this 

report.
Data Acquisition and Processing 7

Data Acquisition and Processing

Data acquisition for the AVO seismograph network 

was accomplished with duplicate EARTHWORM systems 

(Johnson and others, 1995) located in Anchorage and 

Fairbanks. Data were recorded in both continuous and event 

detection modes. Event detected data were collected using 

the EARTHWORM modules Carlstatrig and Carlsubtrig, 

with the Carlstatrig parameters set as follows: Long-termaverage (LTA) time = 8 seconds, Ratio = 2.3, and Quiet = 4. 

Three station triggers from the Carlstatrig module are required 

for an event to trigger Carlsubtrig to create an event record. 

Carlsubtrig was modified such that a two-letter code (table 3) 

was appended to the filename of each trigger to identify the 

first subnetwork that triggered. If four or more subnetworks 

triggered on the same event, all data were saved in a single 

trigger and tagged as a regional event. All data are saved in 

Seismic Analysis Code (SAC) format (Goldstein and others, 

1999).

Volcano 

subnetwork

Network 

code Volcanoes monitored

Akutan ak Akutan Volcano

Aniakchak an Aniakchak Crater

Augustine au Augustine Volcano

Cerberus ce Mount Cerberus

Dutton dt Mount Dutton

Iliamna il Iliamna Volcano

Fourpeaked fo Fourpeaked Mountain

Gareloi ga Mount Gareloi

Great Sitkin gs Great Sitkin Volcano

Kanaga ki Kanaga Volcano

Katmai ka Mount Griggs, Mount Katmai, 

Mount Mageik and Mount 

Martin, Novarupta, Snowy 

Mountain, and Trident Volcano

Korovin ko Korovin Volcano

Little Sitkin ls Little Sitkin Volcano

Makushin ma Makushin Volcano

Okmok ok Okmok Caldera

Pavlof pv Pavlof Volcano

Peulik pl Ugashik-Peulik and Ukinrek Maars

Redoubt rd Redoubt Volcano

Regional Event rg none

Shishaldin sh Fisher Caldera, Isanotski Peaks, and 

Shishaldin Volcano

Spurr sp Mount Spurr

Tanaga ta Tanaga Volcano

Veniaminof vn Mount Veniaminof

Westdahl we Fisher Caldera, and Westdahl Peak

Wrangell wa Mount Wrangell

Table 3. Volcano subnetwork designators.

Event classification Classification code

Volcano-Tectonic (VT) a

Low-Frequency (LF) b

Hybrid h

Shore-Ice i

Cause unknown x

Regional-Volcanic R

Regional-Tectonic E

Teleseismic T

Glacier G

Calibrations C

Other non-seismic O

Table 4. Alaska Volcano Observatory event description codes..

[Lower case letters refer to triggered events that are located. Upper case letters 

are used for triggered events that are not typically located]

Event triggers were processed daily using the interactive 

seismic data analysis program XPICK (Robinson, 1990) 

and the earthquake location program HYPOELLIPSE (Lahr, 

1999). Each event trigger was visually inspected and false 

triggers were deleted. Each subsequent event was identified 

by a description code (table 4) modified after Lahr and others 

(1994), and stored as a comment in the event location pick 

file. Earthquakes with a P-wave and S-wave separation of 

greater than 5 seconds on the closest station were assumed 

to come from non-volcanic sources and typically were not 

located. Each hypocenter was checked using a computer 

algorithm that identified events that did not meet the following 

minimum parameters: three P-phases, two S-phases, and 

standard hypocentral errors less than 15 km, as defined by 

Lahr (1999). If upon reevaluation, the minimum parameters 

could not be met, the event was removed from the final 

catalog listing. The average root-mean-square travel-time 

error was 0.14 seconds and the average vertical and horizontal 

hypocentral errors were 1.4 and 2.1 km, respectively. For the 

earthquakes appearing in the 2011 AVO catalog, 95 percent of 

the earthquakes had an average root-mean-square travel-time 

error less than 0.32. 

At the time of this report’s publication, all hypocentral 

locations of earthquakes in the AVO seismic catalog have 

been made available as part of the Advanced National Seismic 

System (ANSS) catalog. AVO earthquake hypocentral 

locations are currently being added on a daily basis to the 

ANSS catalog after a quality check is performed. The same 

seismograph stations data are available to AVO and the Alaska 

Earthquake Information Center (AEIC) and both organizations 

independently locate some of the same earthquakes. The 

criteria for which earthquakes are located differ for both 

organizations with the overlapping earthquake locations 

comprising 15 percent (561 out of 4,364 earthquiakes) of the 

AVO total (fig. 6). Any earthquake which is both located by 

AVO and AEIC is assigned the AEIC location in the ANSS 

catalog.
8 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Additional data from seismograph stations operated by 

AEIC, Global Seismograph Network, and West Coast and 

Alaska Tsunami Warning Center (WCATWC) were routinely 

utilized in event detection and location. Station parameters for 

the WCATWC and AEIC stations used by AVO in 2011 are 

provided in appendix B.

Seismic Velocity Models

During 2011, AVO used 13 local volcano-specific seismic 

velocity models and a regional seismic velocity model to 

locate earthquakes at Alaskan volcanoes. All velocity models 

were one-dimensional models utilizing horizontal layers to 

approximate the local seismic velocity structure. Each model, 

with one exception, assumed a series of constant velocity 

layers. The single exception was the Akutan velocity model 

(Power and others, 1996), which had a velocity gradient in a 

layer overlying a half-space of constant velocity. 

One or more vertical cylindrical volumes were used 

to model the volcanic source zones for all volcanoes where 

a local velocity model was used. Earthquakes within these 

cylindrical volumes were located with a local model and 

earthquakes outside of the cylindrical volumes were located 

with the regional model. The top of each cylinder was set at 

3 km above sea level and the bottom was set at a depth of 

50 km below sea level. All cylindrical volumes had a radius 

of 20 km with the exception of the cylinders centered on 

Shishaldin and Mount Veniaminof. The cylinder centered 

on Shishaldin had a radius of 30 km in order to encompass 

Fisher Caldera and Isanotski Peaks. The cylinder centered on 

Veniaminof also had a radius of 30 km because of the large 

size of the volcanic edifice. 

The Akutan, Augustine (Power, 1988), Iliamna (Roman 

and others, 2001), Makushin (Searcy, written commun., 2010), 

Okmok (Masterlark and others, 2010), Tanaga (J.A. Power, 

written commun., 2005), Veniaminof (Sánchez, 2005) and 

Westdahl (Dixon and others, 2005) velocity models were 

used to locate hypocenters that fell within cylindrical volumes 

described above, centered on each respective volcano. Five 

overlapping cylinders defined the volume in which the 

Spurr velocity model (Jolly and others, 1994) was used, four 

overlapping cylinders defined the volume for the Redoubt 

velocity model (Lahr and others, 1994), and four overlapping 

cylinders defined the volume for the Katmai model (Searcy, 

2003). The Andreanof velocity model, modified from that in 

Toth and Kisslinger (1984), was used to locate earthquakes 

within a volume defined by three cylinders centered on 

Kanaga Volcano, Mount Moffet, and Great Sitkin Volcano. 

Figure 6. Graph showing comparison of earthquakes, by magnitude (ML), that are uniquely located by AVO staff (green) and those 

located independently by both AVO and AEIC staff (yellow) in 2011

−1 0 1 2 3 4

0

50

100

150

200

250

300

350

400

Magnitude (ML)

Unique to AVO

Shared by AEIC

Number of earthquakes
Seismicity 9

The Cold Bay velocity model (McNutt and Jacob, 1986) was 

used to locate earthquakes that fell within cylindrical volumes 

centered on Mount Dutton, Pavlof Volcano, and Shishaldin 

Volcano. Earthquakes located at Fisher and Isanotski fell 

within the cylindrical volume centered on Shishaldin 

Volcano. Specific velocity models for Aniakchak Crater, 

Mount Cerberus, Fourpeaked Mountain, Mount Gareloi, 

Korovin Volcano, Little Sitkin Volcano, Mount Peulik, and 

Mount Wrangell were not available in 2011 and the regional 

velocity model (Fogleman and others, 1993) was used to 

locate earthquakes near these volcanoes. The cylindrical 

model parameters, regional velocity model, and volcanospecific models used to locate earthquakes in this report are 

summarized in appendix E. Figures showing the volcanic 

source zones modeled by multiple cylinders are shown in 

appendix F.

Seismicity

In 2011, the AVO located 4,364 earthquakes at the 

33 volcanic centers with seismograph subnetworks (fig. 7; 

appendix A). An additional 7,281 events were not located, 

consisting of earthquakes that do not meet the location 

criteria, glacier earthquakes, rockfalls and shore ice events. 

The 4,364 earthquakes located in 2011 represent an increase 

from the 3,405 earthquakes located in 2010 (Dixon and 

others, 2011). Of the earthquakes located in 2011, 84 percent 

(3,651 earthquakes) were located within 20 km of a monitored 

volcanic center. The numbers of located earthquakes 

associated with volcanic centers during the last 2 years are 

shown in table 5. The numbers of located earthquakes in the 

AVO catalog by year are shown in table 6. 

0

5

10

15

20

25

30

35

0 

1000 

2000 

3000 

4000 

5000 

6000 

7000 

8000 

9000 

10000 

1990 2006 

Number of monitored volcanoes

Number of located earthquakes 

Year 

1994 1998 2002 2010 

Figure 7. Graph showing number of earthquakes located per year in the AVO catalog (black line) and number of 

monitored volcanoes per year (green bars)
10 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Using the 2011 earthquake catalog, the magnitude of 

completeness (Mc) for each subnetwork was calculated with 

the exception of seven subnetworks (table 5). The Cerberus, 

Gareloi, Kanaga, Okmok, Pavlof, Veniaminof, and Wrangell 

subnetworks had insufficient numbers of located earthquakes 

in 2011 to calculate a Mc. Mc is the magnitude threshold 

above which we are reasonably certain that an event of Mc 

or greater was detected. The Mc was determined using a 

maximum likelihood estimate of the inflection point in the 

frequency magnitude distribution using the seismology 

analysis software ZMAP (Wiemer, 2001). The Mc ranged 

from 0.3 to 1.4 for the individual subnetworks.

The seismicity at the seismically monitored volcanoes 

showed few deviations from the background level of 

seismicity. Seismicity at Aniakchak, Augustine, Fourpeaked, 

Korovin, Makushin, Shishaldin, and Westdahl were the only 

areas in which increases over the 2010 levels were noted. The 

trend of increasing number of earthquakes at Westdahl Peak 

Volcano subnetwork Earthquakes 

located in 2010

Earthquakes 

located in 2011

2011 

VT

2011

LF

2011

Other

2011

Mc

2002–2011 

MC

Akutan 42 77 66 11 0 0.3 0.3

Aniakchak 12 55 4 51 0 1.4 1.4

Augustine 25 48 46 0 2 0.3 0.1

Cerberus 24 0 0 0 0 – –

Dutton 29 32 32 0 0 1.0 1.0

Fourpeaked 22 90 88 2 0 0.6 0.5

Gareloi 24 23 23 0 0 - 1.2

Great Sitkin 49 25 23 2 0 0.3 0.6

Iliamna 76 54 54 0 0 0.6 -0.4

Kanaga 43 21 21 0 0 – 1.2

Katmai Cluster 965 1,288 1,259 29 0 0.5 0.6

Korovin 32 117 104 12 1 0.7 0.7

Little Sitkin 49 0 0 0 0 – 0.6

Makushin 94 198 197 1 0 0.4 0.7

Okmok 15 23 19 4 0 – 0.9

Pavlof 19 13 6 7 0 – 1.0

Peulik 18 34 34 0 0 1.2 0.9

Redoubt 410 162 123 39 0 0.3 0.4

Shishaldin 195 591 102 489 0 0.6 0.5

Spurr 490 531 531 0 0 0.3 0.2

Tanaga 82 106 97 1 8 1.5 1.1

Veniaminof 22 7 6 1 0 – 1.5

Westdahl 109 156 109 47 0 1.1 1.1

Wrangell 0 0 0 0 0 – 0.9

Totals 2,846 3,651 2,944 696 11 – –

Table 5. Number of earthquakes located for each seismograph subnetwork in 2011 within 20 km of the volcanic centers in 

each subnetwork.. 

[The totals for 2011 are broken into three event types: volcanic-tectonic (VT), low-frequency (LF) and other (all other possible event types shown 

in table 4). Magnitude of completeness (Mc) for AVO seismograph subnetworks using data from 2011 and the period March 2002–December 2011. 

Approximately 25 earthquakes are needed to calculate a Mc]

continued into 2011, a trend that has been ongoing for several 

years. In 2010, the proportion of LF to VT events increased 

when compared to 2009. In 2011, the proportion remains 

the same. The increase in seismicity at Aniakchak is a result 

of a significant number of deep LF events (depths greater 

than 10 km), typically occurring in small bursts of activity, 

throughout 2011. The activity at Augustine, Fourpeaked, 

Korovin, and Shishaldin are well within the annual seismicity 

seen in previous years. The increase in Makushin seismicity 

has coincided with a decrease in the Mc and is easily 

explained by AVO’s ability to located smaller events that went 

unlocated in 2010.

The only subnetwork that saw a decrease in the number 

of located events was the Redoubt network. Redoubt erupted 

in 2009 and the number of located earthquakes at Redoubt 

is still slowly decreasing over time. The numbers of located 

earthquakes at all other subnetworks were similar to that in 

preceding years or have been effected by station outages. 
References Cited 11

Year

Number of 

earthquakes 

located 

per year

Number of 

earthquakes 

located per 

year within 

20 km of 

a volcano

Volcanoes with 

an AVO 

seismograph 

network

1989 911 892 4

1990 3,285 3,148 4

1991 1,119 1,064 4

1992 2,184 2,104 4

1993 697 592 4

1994 441 407 4

1995 850 760 4

1996 6,466 4,259 14

1997 2,930 1,783 17

1998 2,873 1,886 20

1999 2,769 2,343 22

2000 1,551 1,225 22

2001 1,427 1,122 23

2002 7,242 6,578 24

2003 3,911 3,264 27

2004 6,928 6,105 30

2005 9,012 8,146 32

2006 8,666 7,782 33

2007 6,664 5,660 33

2008 7,097 5,318 33

2009 8,829 7,438 33

2010 3,405 2,846 33

2011 4,364 3,651 33

Table 6. Number of earthquakes located per year in the AVO 

earthquake catalog. . Acknowledgments

The contents of this report reflect a great deal of hard 

work by a large number of people including AVO, Alaska 

Earthquake Information Center (AEIC), and USGS personnel 

and various students, interns, and volunteers. We thank the 

AEIC and the West Coast and Alaska Tsunami Warning 

Center for the use of their data. We thank Max Kaufman of 

the University of Alaska Fairbanks and Amy Wright of the 

University of Washington for formal reviews of the text and 

figures.

References Cited

Dixon, J.P., Power, J.A., and Stihler, S.D., 2005, Seismic 

observations of Westdahl Volcano and Western Unimak 

Island, Alaska: 1999-2005, [abs.]: American Geophysical 

Union Transactions, v. 86, Fall Meeting Supplement, 

Abstract S11b-0169.

Dixon, J.P., and Stihler, S.D, Power, J.A., and Searcy, Cheryl, 

2011, Catalog of earthquake hypocenters at Alaskan 

Volcanoes: January 1 through December 31, 2010: U.S. 

Geological Survey Data Series 645, 82 p.

Fogleman, K.A., Lahr, J.C., Stephens, C.D., and Page, R.A., 

1993, Earthquake locations determined by the southern 

Alaska seismograph network for October 1971 through May 

1989: U.S. Geological Survey Open-File Report 93-309, 

54 p.

Goldstein, P., Dodge, D., and Firpo, M., 1999, SAC2000: 

Signal processing and analysis tools for seismologists and 

engineers, in Lee, W.H.K., Kanamori, H., Jennings, P.P., 

Kisslinger, C., eds., International Handbook of Engineers 

and Engineering Seismology, v. 81B, San Diego, CA, 

Academic Press, p. 1613-1614.

Johnson, C.E., Bittenbinder, A., Bogaert, D., Dietz, L., and 

Kohler, W., 1995, EARTHWORM: A flexible approach to 

seismograph network processing: Incorporated Research 

Institutions for Seismology Newsletter, v. 14, no. 2, p. 1-4.

Jolly, A.D., Page, R.A., and Power, J.A., 1994, Seismicity and 

stress in the vicinity of Mt. Spurr volcano, south-central 

Alaska: Journal of Geophysical Research, v. 99, p. 15305-

15318.

Lahr, J.C., 1999, HYPOELLIPSE: A computer program for 

determining local earthquake hypocentral parameters, 

magnitude, and first motion pattern: U.S. Geological Survey 

Open-File Report 99-23, 116 p.

Summary

Between January 1 and December 31, 2011, AVO 

located 4,364 earthquakes, of which 3,651 occurred at or 

near volcanoes in Alaska. There was no significant volcanic 

seismicity noted in 2011. 

Available for download with this report is a compressed 

Unix tar-file containing a summary listing of earthquake 

hypocenters and all necessary HYPOELLIPSE input files to 

recalculate the hypocenters including station locations and 

calibrations, seismic velocity models, and phase information. 

A metadata file in the form of a dataless SEED volume for the 

AVO Seismograph network is included in the data supplement. 

The reader should refer to Lahr (1999) for information on 

file formats and instructions for configuring and running the 

location program HYPOELLIPSE. Continuous waveform 

data for selected AVO seismograph stations are archived and 

available through the Incorporated Research Institutions for 

Seismology (IRIS) (http://www.iris.edu/hq/). Archives of 

waveform data are maintained on DVD-ROM at AVO offices 

in Fairbanks and Anchorage. 

AVO earthquake catalogs for 1989–2010 are listed in 

appendix G. Selected papers published in 2011 that utilized 

AVO seismic data are listed in appendix H.
12 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Lahr, J.C., Chouet, B.A., Stephens, C.D., Power, J.A., and 

Page, R.A., 1994, Earthquake classification, location, and 

error analysis in a volcanic environment: Implications for 

the magmatic system of the 1989–90 eruptions at Redoubt 

Volcano, Alaska: Journal of Volcanology and Geothermal 

Research, v. 62, p. 137-152.

Masterlark, T., Haney, M., Dickinson, H., Fournier, T., and 

Searcy, C., 2010, Rheological and structural controls on the 

deformation of Okmok Volcano, Alaska: FEMs, InSAR, 

and ambient noise tomography: Journal of Geophysical 

Research, v. 115, B02409, doi:10.1029/2009JB006324.

McChesney, P.J., 1999, McVCO Handbook 1999: U.S. 

Geological Survey Open-File Report 99-361, 48 p.

McNutt, S.R., and Jacob, K.H, 1986, Determination of largescale velocity structure of the crust and upper mantle in the 

vicinity of Pavlof Volcano, Alaska: Journal of Geophysical 

Research, v. 91, p. 5013-5022.

Power, J.A., 1988, Seismicity associated with the 1986 

eruption of Augustine Volcano, Alaska: Fairbanks, 

University of Alaska Fairbanks, Masters Thesis, 149 p.

Power, J.A., Paskievitch, J.F., Richter, D.H., McGimsey, R.G., 

Stelling, P., Jolly, A.D., and Fletcher, H.J., 1996, 1996 

seismicity and ground deformation at Akutan Volcano: 

American Geophysical Union Transactions, v. 77, p. F514.

Robinson, M., 1990, XPICK user manual, version 2.7: 

University of Alaska Fairbanks, Seismology Lab, 

Geophysical Institute, 93 p.

Roman, D.C., Power, J.A., Moran, S.C., Cashman, K.V., and 

Stihler, S.D., 2001, Unrest at Iliamna Volcano, Alaska in 

1996, Evidence for a magmatic intrusion [abs.]: American 

Geophysical Union Transactions, v. 82, p. F1329.

Sánchez, J.J., 2005, Volcano seismology from around the 

World: Case studies from Mount Pinatubo (Philippines), 

Galeras (Columbia), Mount Wrangell and Mount 

Veniaminof (Alaska): Fairbanks, University of Alaska 

Fairbanks, Ph.D. dissertation, 208 p. 

Schaefer, J.R., Cameron, C.E., and Nye, C.J., 2009, 

Historically active volcanoes of Alaska: Alaska Division 

of Geological and Geophysical Surveys Miscellaneous 

Publication 133, 1 sheet, scale 1:3,000,000.

Searcy, C.K., 2003, Station corrections for the Katmai Region 

seismograph network: U.S. Geological Survey Open-File 

Report 03-403, 16 p. 

SEED Manual 2010, Standard for the Exchange of Earthquake 

Data, Reference Manual, SEED Format Version 2.4, 

Incorporation Research Institution for Seismology, 212 p.

Toth, T., and Kisslinger, C., 1984, Revised focal depths and 

velocity model for local earthquakes in the Adak seismic 

zone: Bulletin of the Seismological Society of America, v. 

74, p. 1349-1360. 

Wiemer, S., 2001, A software package to analyze seismicity: 

ZMAP: Seismological Research Letters, v. 72, p. 373-382.
Appendix A 13

Appendix A. Maps of Monitored Volcanoes with Earthquake Hypocenters 

Calculated in 2011. 

Figure A1. Summary plots of earthquakes located near Mount Wrangell in 2011. Open circles indicate hypocenters 

shallower than 20 km with symbols scaled with magnitude. Permanent seismograph stations are shown by open 

squares and labeled by station code. Solid triangles are used to show volcanic centers. Vertical exaggeration is x1.5. 

See appendix B for station information.
14 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure A2. Summary plots of earthquakes located near Mount Spurr in 2011. Open circles indicate hypocenters 

shallower than 20 km and open triangles indicate hypocenters with depths of 20 km and deeper. Hypocenter symbols 

are scaled with magnitude. Permanent seismograph stations are shown by open squares and labeled by station code.

Solid triangles are used to show volcanic centers. Vertical exaggeration is x0.6. See appendix B for station information.
Appendix A 15

Figure A3. Summary plots of earthquakes located near Redoubt Volcano in 2011. Open circles indicate hypocenters 

shallower than 20 km and open triangles indicate hypocenters with depths of 20 km and deeper. Hypocenter symbols 

are scaled with magnitude. Permanent seismograph stations are shown by open squares and labeled by station code.

Solid triangles are used to show volcanic centers. Vertical exaggeration is x0.6. See appendix B for station information.
16 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure A4. Summary plots of earthquakes located near Iliamna Volcano in 2011. Open circles indicate hypocenters

shallower than 20 km and open triangles indicate hypocenters with depths of 20 km and deeper. Hypocenter symbols 

are scaled with magnitude. Permanent seismograph stations are shown by open squares and labeled by station code.

Solid triangles are used to show volcanic centers. Vertical exaggeration is x0.6. See appendix B for station information.
Appendix A 17

Figure A5. Summary plots of earthquakes located near Augustine Volcano in 2011. Open circles indicate hypocenters 

shallower than 20 km with symbols scaled with magnitude. Permanent seismograph stations are shown by open 

squares and labeled by station code. Solid triangles are used to show volcanic centers. Vertical exaggeration is x0.2. 

See appendix B for station information. 
18 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure A6. Summary plots of earthquakes located near Fourpeaked Mountain in 2011. Open circles show hypocenter 

locations shallower than 20 km. Hypocenter symbols are scaled with magnitude. Permanent seismograph stations are 

shown by open squares and labeled by station code. Solid triangles are used to show volcanic centers. Vertical 

exaggeration is x0.7. See appendix B for station information.
Appendix A 19

Figure A7. Summary plots of earthquakes located within the Katmai volcanic cluster in 2011. Open circles indicate 

hypocenters shallower than 20 km and open triangles indicate hypocenters with depths of 20 km and deeper with 

symbols scaled with magnitude. Permanent seismograph stations are shown by open squares and labeled by station 

code. Solid triangles are used to show volcanic centers. Vertical exaggeration is x1.4. See appendix B for station 

information.
20 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure A8. Summary plots of earthquakes located near Snowy Mountain in the Katmai volcanic cluster in 2011. Open 

circles show hypocenter locations shallower than 20 km and open triangles indicate times of hypocenters with depths of 

20 km and deeper. Hypocenter symbols are scaled with magnitude. Permanent seismograph stations are shown by 

open squares and labeled by station code. Solid triangles are used to show volcanic centers. Vertical exaggeration is 

x0.4. See appendix B for station information.
Appendix A 21

Figure A9. Summary plots of earthquakes located near Mount Griggs in the Katmai volcanic cluster in 2011. Open 

circles show hypocenter locations shallower than 20 km. Hypocenter symbols are scaled with magnitude. Permanent 

seismograph stations are shown by open squares and labeled by station code. Solid triangles are used to show volcanic 

centers. Vertical exaggeration is x0.25. See appendix B for station information. Several earthquakes that appear on this 

figure appear on other figures.
22 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure A10. Summary plots of earthquakes located near Mount Katmai in the Katmai volcanic cluster in 2011. Open 

circles show hypocenter locations shallower than 20 km and open triangles indicate hypocenters with depths of 20 km 

and deeper. Hypocenter symbols are scaled with magnitude Permanent seismograph stations are shown by open 

squares and labeled by station code. Solid triangles are used to show volcanic centers. Vertical exaggeration is x0.2. 

See appendix B for station information. Several earthquakes that appear on this figure appear on other figures.
Appendix A 23

Figure A11. Summary plots of earthquakes located near Novarupta and Trident Volcano in the Katmai volcanic cluster 

in 2011. Open circles show hypocenter locations shallower than 20 km and open triangles indicate hypocenters with 

depths of 20 km and deeper. Hypocenter symbols are scaled with magnitude. Permanent seismograph stations are 

shown by open squares and labeled by station code. Solid triangles are used to show volcanic centers. Vertical 

exaggeration is x0.2. See appendix B for station information. Several earthquakes that appear on this figure appear on 

other figures.
24 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure A12. Summary plots of earthquakes located near Mount Mageik and Mount Martin in the Katmai volcanic cluster 

in 2011. Open circles show hypocenter locations shallower than 20 km and open triangles indicate hypocenters with 

depths of 20 km and deeper. Hypocenter symbols are scaled with magnitude. Permanent seismograph stations are 

shown by open squares and labeled by station code. Solid triangles are used to show volcanic centers. Vertical 

exaggeration is x0.25. See appendix B for station information. Several earthquakes that appear on this figure appear on 

other figures.
Appendix A 25

Figure A13. Summary plots of earthquakes located near Mount Peulik in 2011. Open circles indicate hypocenters 

shallower than 20 km with symbols scaled with magnitude. Permanent seismograph stations are shown by open 

squares and labeled by station code. Solid triangles are used to show volcanic centers. Vertical exaggeration is x1.0. 

See appendix B for station information.
26 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure A14. Summary plots of earthquakes located near Aniakchak Crater in 2011. Open circles indicates hypocenters 

shallower than 20 km and open triangles indicate hypocenters with depths of 20 km and deeper with symbols scaled 

with magnitude. Permanent seismograph stations are shown by open squares and labeled by station code. Solid 

triangles are used to show volcanic centers. Vertical exaggeration is x0.35. See appendix B for station information.
Appendix A 27

Figure A15. Summary plots of earthquakes located near Mount Veniaminof in 2011. Open circles show hypocenter 

locations shallower than 20 km and open triangles indicates hypocenters with depths of 20 km and deeper. Permanent 

seismograph stations are shown by open squares and labeled by station code. Solid triangles are used to show 

volcanic centers. Vertical exaggeration is x0.8. See appendix B for station information. 
28 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure A16. Summary plots of earthquakes located near Pavlof Volcano in 2011. Open circles indicate hypocenters 

shallower than 20 km and open triangles indicate hypocenters with depths of 20 km and deeper with symbols scaled 

with magnitude. Permanent seismograph stations are shown by open squares and labeled by station code. Solid 

triangles are used to show volcanic centers. Vertical exaggeration is x0.35. See appendix B for station information.
Appendix A 29

Figure A17. This summary plot shows earthquakes located near Mount Dutton in 2011. Open circles show hypocenter 

locations shallower than 20 km. Hypocenter symbols are scaled with magnitude. Permanent seismograph stations are 

shown by open squares and labeled by station code. Solid triangles are used to show volcanic centers and solid 

squares are used to show other points of interest. Vertical exaggeration is x0.3. See appendix B for station information.
30 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure A18. Summary plots of earthquakes located near Unimak Island in 2011. Open circles indicates hypocenters 

shallower than 20 km and open triangles indicates hypocenters with depths of 20 km and deeper with symbols scaled 

with magnitude. Permanent seismograph stations are shown by open squares and labeled by station code. Solid 

triangles are used to show volcanic centers. Vertical exaggeration is x1.4. See appendix B for station information.
Appendix A 31

Figure A19. Summary plots of earthquakes located near Shishaldin Volcano in 2011. Open circles indicate hypocenters 

shallower than 20 km and open triangles indicate hypocenters with depths of 20 km and deeper with symbols scaled 

with magnitude. Permanent seismograph stations are shown by open squares and labeled by station code. Solid 

triangles are used to show volcanic centers. Vertical exaggeration is x0.35. See appendix B for station information.
32 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure A20. Summary plots of earthquakes located near Westdahl Peak in 2011. Open circles show hypocenter 

locations shallower than 20 km and open triangles indicate hypocenters with depths of 20 km and deeper. Hypocenter 

symbols are scaled with magnitude. Permanent seismograph stations are shown by open squares and labeled by 

station code. Solid triangles are used to show volcanic centers and solid squares are used to show other points of 

interest. Vertical exaggeration is x0.4. See appendix B for station information.
Appendix A 33

Figure A21. Summary plots of earthquakes located near Akutan Peak in 2011. Open circles indicate hypocenters 

shallower than 20 km and open triangles indicates hypocenters with depths of 20 km and deeper with symbols scaled 

with magnitude. Permanent seismograph stations are shown by open squares and labeled by station code. Solid 

triangles are used to show volcanic centers. Vertical exaggeration is x0.45. See appendix B for station information.
34 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure A22. Summary plots of earthquakes located near Makushin Volcano in 2011. Open circles show hypocenter 

locations shallower than 20 km and open triangle indicate hypocenters with depths of 20 km and deeper. Hypocenter 

symbols are scaled with magnitude. Permanent seismograph stations are shown by open squares and labeled by 

station code. Solid triangles are used to show volcanic centers and solid squares are used to show other points of 

interest. Vertical exaggeration is x0.7. See appendix B for station information.
Appendix A 35

Figure A23. Summary plots of earthquakes located on Umnak Island in 2011. Open circles show hypocenter locations 

shallower than 20 km and open triangles indicate hypocenters with depths of 20 km and deeper. Hypocenter symbols 

are scaled with magnitude. Permanent seismograph stations are shown by open squares and labeled by station code.

Solid triangles are used to show volcanic centers and solid squares are used to show other points of interest. Vertical 

exaggeration is x1.1. See appendix B for station information.
36 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure A24. Summary plots of earthquakes located near Korovin Volcano and Mount Kliuchef in 2011. Open circles 

show hypocenter locations shallower than 20 km and open triangles indicate hypocenters with depths of 20 km and 

deeper. Hypocenter symbols are scaled with magnitude. Permanent seismograph stations are shown by open squares 

and labeled by station code. Solid triangles are used to show volcanic centers and solid squares are used to show other 

points of interest. The gray shaded area in time depth plot shows the time frame the subnetwork was not on the 

monitored volcano list. Vertical exaggeration is x055. See appendix B for station information.
Appendix A 37

Figure A25. Summary plots of earthquakes located in the Middle Andreanof Islands in 2011. Open circles indicate 

hypocenters shallower than 20 km and open triangles indicate hypocenters with depths of 20 km and deeper. 

Hypocenter symbols are scaled with magnitude. Permanent seismograph stations are shown by open squares and 

labeled by station code. Solid triangles are used to show volcanic centers and solid squares are used to show other 

points of interest. Vertical exaggeration is x1.3. See appendix B for station information.
38 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure A26. Summary plots of earthquakes located near Great Sitkin Volcano in 2011. Open circles indicate 

hypocenters shallower than 20 km and are scaled with magnitude. Permanent seismograph stations are shown by open 

squares and labeled by station code. Solid triangles are used to show volcanic centers. Vertical exaggeration is x0.25. 

See appendix B for station information.
Appendix A 39

Figure A27. Summary plots of earthquakes located near Kanaga Volcano in 2011. Open circles indicate hypocenters 

shallower than 20 km and are scaled with magnitude. Permanent seismograph stations are shown by open squares 

and labeled by station code. Solid triangles are used to show volcanic centers. Vertical exaggeration is x0.25. See 

appendix B for station information.
40 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure A28. Summary plots of earthquakes located in the Western Andreanof Islands in 2011. Open circles indicates 

hypocenters shallower than 20 km and open triangles indicate hypocenters with depths of 20 km and deeper with 

symbols scaled by magnitude. Permanent seismograph stations are shown by open squares and labeled by station 

code. Solid triangles are used to show volcanic centers. Vertical exaggeration is x0.4. See appendix B for station 

information.
Appendix A 41

Figure A29. Summary plots of earthquakes located on Semisopochnoi Island in 2011. Open circles indicates 

hypocenters shallower than 20 km and are scaled with magnitude. Permanent seismograph stations are shown by open 

squares and labeled by station code. Solid triangles are used to show volcanic centers. The gray shaded area in time 

depth plot shows the time frame the subnetwork was not on the monitored volcano list. Vertical exaggeration is x0.3. 

See appendix B for station information.
42 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure A30. Summary plots of earthquakes located near Little Sitkin Volcano in 2011. Open circles indicate hypocenters 

shallower than 20 km and are scaled with magnitude. Permanent seismograph stations are shown by open squares 

and labeled by station code. Solid triangles are used to show volcanic centers. The gray shaded area in time depth plot 

shows the time frame the subnetwork was not on the monitored volcano list. Vertical exaggeration is x0.2. See 

appendix B for station information.
Appendix B 43

///

Appendix B. Parameters for AVO Seismograph Stations (datum NAD27) in 

2011. 

This list includes station parameters for seismograph stations operated by the Alaska Volcano Observatory (AVO), 

Alaska Earthquake Information Center (AEIC) and the West Coast-Alaska Tsunami Warning Center (WC-ATWC) that 

were used to locate earthquakes in the AVO catalog. The open date is the date that data were first recorded and the 

close date is the date that recording was stopped. Discounting temporary data outages, data are available for each listed 

station between the open and close date. Stations still in operation are indicated by a dash in the close date column. 

Akutan Peak subnet (13 stations – 29 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

AHB 54 06.916 -165 48.943 447 L4 1996/07/24 -

AKBB3 54 05.905 -165 55.907 310 CMG-6TD 2005/07/05 -

AKGG3 54 11.930 -165 59.495 326 CMG-6TD 2003/06/27 -

AKLV3 54 09.762 -165 57.336 551 CMG-6TD 2003/07/02 -

AKMO3 54 05.471 -166 00.634 277 CMG-6TD 2003/06/25 -

AKRB3 54 07.803 -166 04.125 334 CMG-6TD 2003/06/29 -

AKS3 54 06.624 -165 41.803 213 L22 1996/07/24 -

AKSA3 54 06.624 -165 41.803 213 CMG-6TD 2011/07/14 -

AKT3 54 08.150 -165 46.200 12 CMG-40T 1996/03/18 -

AKV 54 07.571 -165 57.763 863 L4 1996/07/24 -

HSB 54 11.205 -165 54.743 497 L4 1996/07/24 -

LVA 54 09.654 -166 02.025 457 L4 1996/07/24 -

ZRO 54 05.494 -165 58.678 446 L4 1996/07/24 -

Aniakchak Crater subnet (6 stations – 8 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

ANNE 56 54.763 -158 03.534 705 L4 1997/07/18 -

ANNW 56 57.986 -158 12.895 816 L4 1997/07/18 -

ANON3 56 55.188 -158 10.293 445 L22 2000/07/10 -

ANPB 56 48.141 -158 16.847 658 L4 1997/07/18 -

ANPK 56 50.499 -158 07.572 972 L4 1997/07/18 -

AZAC 56 53.727 -158 13.841 1,057 L4 2003/07/12 -

Augustine Volcano subnet (10 stations – 19 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

AU223 59 22.247 -153 21.301 105 SM 2007/09/01 -

AUE*P 59 22.308 -153 22.504 168 S13 1980/10/29 -

AUH 59 21.833 -153 26.591 890 S13 1978/12/01 -

AUI3 59 20.110 -153 25.660 293 S13 1978/04/06 -

AUJK 59 20.997 -153 24.509 377 L4 2011/08/16 -

AUL 59 22.937 -153 26.142 360 S13 1980/10/29 -

AUL3 59 22.937 -153 26.142 360 CMG-6TD 1997/08/27 -

AUNW* 59 22.694 -153 28.609 160 L4 2007/03/15 -

AUP 59 21.805 -153 25.210 1,033 S13 1977/09/22 -

AUSER 59 20.481 -153 23.850 152 L4 2006/02/03 2011/08/16

AUW 59 22.205 -153 28.249 276 S13 1976/10/17 -

Mount Cerberus Subnet (6 stations - 8 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

CEAP 52 00.146 179 34.667 244 L4 2005/09/17 -

CEPE 51 57.949 179 38.950 335 L4 2005/09/17 -

CERA 51 54.419 179 41.074 305 L4 2005/09/26 -

CERB3 51 55.886 179 37.783 305 L4-3D 2005/09/18 -

CESW 51 54.060 179 33.800 238 L4 2005/09/18 -

CETU 51 57.965 179 29.651 335 L4 2005/09/22 -
44 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Dutton subnet (5 stations - 5 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

BLDY 55 11.670 -162 47.018 259 L4 1996/07/11 -

DOL 55 08.976 -161 51.702 439 L4 1996/07/11 -

DRR3 54 58.014 -162 15.665 457 L4 1996/07/11 -

DT1 55 06.427 -162 16.859 198 L4 1991/06/21 -

DTN 55 08.744 -162 15.419 396 S13 1988/07/16 -

Fourpeaked subnet (4 stations - 7 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

CDD 58 55.771 -153 38.558 622 S13 1981/08/17 -

FONW*P 58 50.086 -153 55.102 905 L-4 2006/10/19 -

FOPK* 58 45.480 -153 28.433 546 L4 2006/09/25 -

FOSS*P 58 47.965 -153 41.699 1,268 L-4 2006/10/10 -

Gareloi Volcano subnet (6 stations - 8 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

GAEA 51 46.980 -178 44.810 326 L4 2003/08/30 -

GAKI 51 33.267 -178 48.725 99 L4 2003/09/01 -

GALA 51 45.704 -178 46.292 315 L4 2003/08/30 -

GANE 51 49.135 -178 46.603 322 L4 2003/09/02 -

GANO 51 49.220 -178 48.230 451 L4 2003/09/02 -

GASW3 51 46.731 -178 51.276 248 L22 2003/08/30 -

Great Sitkin Volcano subnet (6 stations - 8 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

GSCK 52 00.712 -176 09.718 384 L4 1999/09/15 -

GSIG 51 59.181 -175 55.502 407 L4 1999/09/03 -

GSMY 52 02.594 -176 03.376 418 L4 1999/09/03 -

GSSP 52 05.566 -176 10.541 295 L4 1999/09/15 -

GSTD3 52 03.356 -176 08.685 873 L22 1999/09/03 -

GSTR 52 05.655 -176 03.546 536 L4 1999/09/03 -

Iliamna Volcano subnet (6 stations - 8 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

ILI 60 04.877 -152 57.502 771 L4 1987/09/15 -

ILS 59 57.454 -153 04.083 1,125 S13 1996/08/28 -

ILW 60 03.585 -153 08.222 1,646 S13 1994/09/09 -

INE 60 03.630 -153 03.732 1,634 S13 1990/08/29 -

IVE3 60 01.014 -153 00.981 1,173 S13,L22 1996/09/19 -

IVS 60 00.55 -153 04.85 2,332 S13 1990/08/29 -

Kanaga Volcano subnet (6 stations - 6 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

KICM 51 55.136 -177 11.718 183 L4 1999/09/15 -

KIKV 51 52.730 -177 10.223 411 L4 1999/09/15 -

KIMD 51 45.697 -177 14.093 183 L4 1999/09/15 -

KINC 51 55.884 -177 07.657 198 L4 1999/09/15 -

KIRH 51 53.976 -177 05.611 309 L4 1999/09/03 -

KIWB 51 51.183 -177 09.049 244 L4 1999/09/03 -
Appendix B 45

///

Katmai Volcanic Cluster subnet (20 stations - 30 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

ACH3 58 12.64 -155 19.56 960 L22 1996/07/25 -

ANCK 58 11.93 -155 29.64 869 L4 1996/07/25 -

CAHL 58 03.15 -155 18.09 807 L4 1996/07/25 -

CNTC 58 15.87 -155 53.02 1,158 L4 1996/07/25 -

KABR 58 07.87 -154 58.15 884 L4 1998/08/12 -

KABU3 58 16.225 -155 16.934 1,065 CMT-6TD 2004/08/01 -

KAHC 58 38.94 -155 00.36 1,250 L4 1998/10/12 -

KAHG 58 29.64 -154 32.78 923 L4 1998/10/12 -

KAIC 58 29.10 -155 02.75 734 L4 1998/10/12 -

KAKN3 58 17.819 -155 03.668 1,049 CMG-6TD 2004/08/01 -

KAPH3 58 35.81 -154 20.81 907 L22 1998/10/12 -

KARR 58 29.87 -154 42.20 610 L4 1998/10/12 -

KAWH 58 23.02 -154 47.95 777 L4 1998/10/12 -

KBM 58 16.50 -155 12.10 732 L4 1991/07/22 -

KCE 58 14.60 -155 11.00 777 L4 1991/07/22 -

KCG3 58 18.457 -155 06.684 762 L22 1988/08/01 -

KEL 58 26.401 -155 44.442 975 L4 1988/08/01 -

KJL 58 03.24 -155 34.39 792 L4 1996/07/25 -

KVT 58 22.90 -155 17.70 457 L4 1988/08/01 -

MGLS 58 08.06 -155 09.65 472 L4 1996/07/25 -

Korovin Volcano subnet (7 stations - 9 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

KOFP 52 16.508 -174 05.832 662 L4 2004/07/02 -

KOKL 52 19.393 -174 12.012 758 L4 2004/07/05 -

KOKV3 52 21.685 -174 09.915 776 L22 2004/07/05 -

KONE 52 23.611 -174 07.156 253 L4 2004/07/10 -

KONW 52 23.790 -174 12.629 334 L4 2004/07/04 -

KOSE 52 20.749 -174 02.909 625 L4 2004/07/07 -

KOWE 52 21.940 -174 15.040 527 L4 2004/07/06 -

Little Sitkin subnet (4 stations - 6 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

LSNW 51 58.232 178 31.011 290 L4 2005/09/30 -

LSPA3 51 57.413 178 34.405 335 L4-3D 2005/09/30 -

LSSA 51 56.973 178 30.793 549 L4 2005/09/28 -

LSSE 51 55.993 178 34.139 335 L4 2005/09/27 -

Makushin Volcano subnet (7 stations - 9 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

MCIR 53 57.086 -166 53.529 800 L4 1996/07/25 -

MGOD 53 47.683 -166 52.561 650 L4 1996/07/25 -

MNAT 53 53.028 -166 41.016 397 L4 1996/07/25 -

MREP 53 48.629 -166 44.736 785 L4 2002/01/01 -

MSOM 53 48.978 -166 56.187 146 L4 1996/07/25 -

MSW3 53 54.939 -166 47.191 423 L22 1996/07/25 -

MSWB 53 54.939 -166 47.191 423 CMG-6TD 2011/08/04 -

MTBL 53 58.136 -166 40.760 810 L4 1996/07/25 -
46 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Okmok Caldera subnet (13 stations - 21 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

OKAK 53 24.740 -168 21.465 165 L4 2005/07/11 -

OKCE3 53 25.622 -168 09.858 515 CMG-6TD 2003/01/09 -

OKCF 53 23.749 -168 08.175 685 L4 2003/01/09 -

OKER 53 27.278 -168 02.960 956 L4 2003/01/09 -

OKFG3 53 24.702 -167 54.568 201 CMG-6TD 2003/01/09 -

OKID 53 28.645 -167 48.972 437 L4 2003/01/09 -

OKNC3 53 27.407 -168 07.426 404 CMG-6TD 2010/09/01 -

OKRE 53 31.215 -168 09.846 422 L4 2003/01/09 -

OKSO3 53 21.447 -168 09.591 460 CMG-6TD 2004/09/01 -

OKSP 53 15.156 -168 17.431 608 L4 2003/01/09 -

OKTU 53 23.035 -168 02.466 646 L4 2003/01/09 -

OKWE 53 28.328 -168 14.388 445 L4 2003/01/09 -

OKWR 53 26.084 -168 12.333 1,017 L4 2003/01/09 -

Pavlof Volcano subnet (7 stations - 9 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

BLHA 55 42.276 -162 03.540 411 L4 1996/07/11 -

HAG 55 19.068 -161 54.144 516 L4 1996/07/11 -

PN7AP 55 26.020 -161 59.713 838 L4 1996/07/11 -

PS1A 55 25.254 -161 44.496 283 L4 1996/07/11 -

PS4A 55 20.808 -161 51.276 322 L4 1996/07/11 -

PV63 55 27.217 -161 55.112 747 L22 1996/07/11 -

PVV 55 22.440 -161 47.396 173 L4 1996/07/11 -

Mount Peulik subnet (7 stations - 9 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

PLBL 57 41.990 -156 49.131 461 L4 2004/08/01 -

PLK1 57 48.114 -156 36.433 78 L4 2004/08/01 -

PLK2 57 45.852 -156 19.458 401 L4 2004/08/01 -

PLK33 57 41.320 -156 16.044 494 L22 2004/08/01 -

PLK4 57 37.928 -156 21.464 1,031 L4 2004/08/01 -

PLK5 57 59.864 -156 52.662 49 L4 2004/08/01 -

PLWL 58 02.696 -156 20.479 585 L4 2004/08/01 -

Redoubt Volcano subnet (12 stations - 31 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

DFRP 60 35.514 -152 41.160 1,090 L4 1988/08/15 -

NCT 60 33.728 -152 55.759 1,120 L4 1988/08/14 -

NCTB 60 33.764 -152 55.621 1,136 CMG-6TD 2011/08/24 -

RDDF3 60 35.507 -152 41.154 1,134 CMG-6TD 2010/01/11 -

RDDR 60 35.093 -152 35.181 905 L4 2009/07/01 -

RDJH3 60 35.461 -152 48.213 1,414 CMG-6TD 2009/02/04 -

RDN 60 31.377 -152 44.273 1,400 L4 1988/08/13 -

RDSO3 60 27.254 -152 44.581 1,557 CMG-6TD 2011/08/29 -

RDT 60 34.394 -152 24.315 930 L4 1971/08/09 -

RDWB3 60 29.284 -152 50.415 1,546 CMG-6TD 2009/02/04 -

RED3 60 25.209 -152 46.316 1,071 L4 1974/00/00 -

REDB 60 25.209 -152 46.316 1,071 CMG-6TD 2011/08/24 -

REF3* 60 29.362 -152 41.500 1,801 L22 1990/03/14 -

RSO 60 27.73 -152 45.23 1,921 L4 1990/03/01 -

Shishaldin Volcano subnet (7 stations - 11 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

BRPK 54 38.730 -163 44.449 393 L4 1997/07/27 -

ISLZ 54 43.559 -163 42.663 466 L4 2008/08/17 -

ISNN 54 49.937 -163 46.706 466 L4 1997/07/27 -

SSBA3 54 46.363 -164 07.470 766 CMG-6TD 2008/08/01 -

SSLNP 54 48.709 -163 59.756 637 L4 1997/07/27 -

SSLS3 54 42.718 -163 59.926 817 L22 1997/07/27 -

SSLW 54 46.307 -164 07.282 636 L4 1997/07/27 -
Appendix B 47

///

Mount Spurr subnet (17 stations - 32 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

BGL 61 16.012 -152 23.340 1,127 L4 1989/08/13 -

BKG 61 04.21 -152 15.76 1,009 L4 1991/07/01 -

CGL 61 18.46 -152 00.40 1,082 L4 1981/09/22 -

CKL 61 11.782 -152 20.268 1,281 L4 1989/08/05 -

CKN 61 13.44 -152 10.89 735 L4 1991/08/19 -

CKT 61 12.05 -152 12.37 975 L4 1992/09/16 -

CP2 61 15.85 -152 14.51 1,981 L4 1992/10/23 -

CRP3 61 16.02 -152 09.33 1,622 L4 1981/08/26 -

NCG 61 24.22 -152 09.40 1,244 L4 1989/08/06 -

SPBG3 61 15.583 -152 22.194 1,087 CMG-6TD 2004/09/09 -

SPCG3 61 17.512 -152 01.228 1,329 CMG-6TD 2004/09/08 -

SPCN 61.13.497 -152 10.992 735 CMG-6TD 2010/09/01 -

SPCP 61 15.967 -152 09.174 1,616 CMG-6TD 2010/10/02 -

SPCR3 61 12.051 -152 12.409 984 CMG-6TD 2004/09/08 -

SPNN3 61 22.001 -152 41.944 1,666 CMG-6TD 2011/08/01 -

SPNWR 61 20.826 -152 36.236 1,040 L4 2004/08/17 2011/08/01

SPU 61 10.90 -152 03.26 800 L4 1971/08/10 -

SPWE 61 16.441 -152 33.410 1,233 L4 2004/08/18 -

Tanaga Volcano subnet (6 stations - 8 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

TACS 51 51.792 -178 08.363 918 L4 2003/08/28 -

TAFL 51 45.396 -177 53.867 186 L4 2003/08/28 -

TAFP3 51 54.003 -177 58.997 440 L22 2003/08/27 -

TANO 51 54.942 -178 07.249 269 L4 2003/08/24 -

TAPA 51 48.932 -177 48.770 640 L4 2003/08/27 -

TASE 51 50.099 -178 02.222 682 L4 2003/08/24 -

Mount Veniaminof subnet (9 stations - 9 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

BPBC 56 35.383 -158 27.153 584 L4 2002/10/03 -

VNFG 56 17.140 -159 33.066 1,068 L4 2002/02/06 -

VNHG 56 13.267 -159 09.853 966 L4 2002/02/06 -

VNKR 56 01.871 -159 22.068 620 L4 2002/02/06 -

VNNF 56 17.022 -159 18.961 1,153 L4 2002/06/20 -

VNSG 56 07.549 -159 05.121 761 L4 2002/02/06 -

VNSS 56 13.600 -159 27.290 1,733 L4 2002/02/06 -

VNSW 56 04.317 -159 33.508 716 L4 2002/06/20 -

VNWF 56 09.104 -159 33.733 1,095 L4 2002/02/06 -

Westdahl Peak subnet (6 stations - 8 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

WEBT 54 35.468 -164 45.183 467 L4 2008/08/02 -

WECS 54 31.853 -164 46.653 642 L4 2008/08/03 -

WESE 54 28.389 -164 35.038 953 L4 1998/08/28 -

WESN 54 34.620 -164 34.704 549 L4 1998/10/17 -

WESP3 54 28.611 -164 43.277 937 L22 2008/07/31 -

WTUG 54 50.847 -164 23.117 636 L4 1998/10/17 -

Mount Wrangell subnet (4 stations - 6 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

WACK3 61 59.178 -144 19.703 2,280 L22 2000/07/31 -

WANC 62 00.189 -144 4.195 4,190 L4 2000/07/31 -

WASW 61 55.692 -144 10.346 2,196 L4 2001/08/03 -

WAZA 62 04.506 -144 9.132 2,531 L4 2001/08/03 -
48 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

AVO Regional stations (10 stations - 12 components)

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

ADAG 51 58.812 -176 36.104 286 L4 1999/09/15 -

AMKA3 51 22.70 179 18.11 116 Tri-40 2005/10/14 -

BGM 59 23.56 -155 13.76 625 L4 1978/09/08 -

BGR 60 45.45 -152 25.06 985 L4 1991/07/01 -

ETKA 51 51.712 -176 24.351 290 L4 1999/09/15 -

MMN 59 11.11 -154 20.20 442 S13 1981/08/22 -

OPT 59 39.192 -153 13.796 602 S13 1974/00/00 -

PDB 59 47.09 -154 11.37 360 L4 1978/09/09 -

STLK 61 29.926 -151 49.963 945 L4 1997/09/01 -

SYI 58 36.607 -152 23.485 149 L4 1997/09/01 -

AEIC, Global Seismograph Network and WCATWC stations

Station Latitude (N) Longitude (E) Elevation (m) Seismometer Open date Close date

AKUT 54 8.112 -174 11.730 55 STS-2 2002/10/03 -

ATKA 52 12.162 -174 11.730 55 CMG-3ESP 2002/10/03 -

CUT 62 24.282 -150 16.164 168 L4 1986/07/18 -

FALS 54 51.438 -163 24.930 46 CMG-3ESP 2002/06/19 -

KDAK 57 46.968 -152 35.010 152 KS-54000 1997/06/09 -

NIKH 52 58.386 -143 58.032 507 STS-2 2007/06/21 -

NKA 60 44.580 -151 14.274 100 L4 1971/09/13 -

SLK 60 30.738 -150 13.254 655 L4 1984/07/30 -

SSN 61 27.840 -150 44.664 1,293 CMG-5T 1972/08/16 -

UNV 53 50.790 -166 30.120 67 CMG-3ESP 1999/02/19 -

Station Codes: 3

 Three-component station P Pressure sensor collocated with seismometer R Pressure sensor collocated with seismometer

* Seismic station has a both a high-gain and low-gain vertical component

# Temporary three-component broadband station

 

Seismometer Codes: CMG-40T: Guralp CMG-40T three-component broadband seismometer

CMG-5T: Guralp CMG-5T three-component broadband seismometer

CMG-6TD: Guralp CMG-6TD three-component broadband seismometer

CMG-3ESP: Guralp CMG-3ESP three-component broadband seismometer

KS-54000: three-component broadband seismometer

L4, L4-3D: Mark Products L4 or L4-3D single-component short-period seismometer

L22: Mark Products L22 three-component short-period seismometer

S13: Teledyne Geotech S13 single-component short-period seismometer

SM: Ref Tek 130-ANSS/02 strong motion seismometer

STS-2: Streckeisen STS-2 broadband seismometer

Tri-40: Nanometrics Trillium 40 three-component broadband seismometer
Appendix C 49

Appendix C. Locations (datum NAD27) of the AVO Seismograph Stations in 

2011. 

Figure C1. Regional AVO seismograph stations in Cook Inlet in 2011. Permanent stations are shown 

by open squares. Closed triangles show volcanic centers.

Figure C2. AVO seismograph stations near Mount Wrangell in 2011. Permanent stations are shown 

by open squares. Closed triangles show volcanic centers.
50 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure C3. AVO seismograph stations near Mount Spurr in 2011. Permanent stations are shown by 

open squares. Closed triangles show volcanic centers.

Figure C4. AVO seismograph stations near Redoubt Volcano in 2011. Permanent stations are shown 

by open squares. Closed triangles show volcanic centers.
Appendix C 51

Figure C5. AVO seismograph stations near Iliamna Volcano in 2011. Permanent stations are shown 

by open squares. Closed triangles show volcanic centers.

Figure C6. AVO seismograph stations near Augustine Volcano in 2011. Permanent stations are 

shown by open squares. Closed triangles show volcanic centers.
52 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure C7. AVO seismograph stations near Fourpeaked Mountain in 2011. Permanent stations are 

shown by open squares. Closed triangles show volcanic centers.

Figure C8. AVO seismograph stations near the Katmai volcanic cluster in 2011. Permanent stations 

are shown by open squares. Closed triangles show volcanic centers.
Appendix C 53

Figure C9. AVO seismograph stations near the Mount Peulik in 2011. Permanent stations are shown 

by open squares. Closed triangles show volcanic centers.

Figure C10. AVO seismograph stations near Aniakchak Crater in 2011. Permanent stations are 

shown by open squares. Closed triangles show volcanic centers.
54 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure C11. AVO seismograph stations near Mount Veniaminof in 2011. Seismograph station BPBC 

is not shown and is located 70 km northeast of Mount Veniaminof. Permanent stations are shown by 

open squares. Closed triangles show volcanic centers.

Figure C12. Regional AVO seismograph stations on the Alaska Peninsula in 2011. Permanent stations 

are shown by open squares. Closed triangles show volcanic centers.
Appendix C 55

Figure C13. AVO seismograph stations near Pavlof Volcano in 2011. Permanent stations are shown 

by open squares. Closed triangles show volcanic centers.

Figure C14. AVO seismograph stations near Mount Dutton in 2011. Permanent stations are shown 

by open squares. Closed triangles show volcanic centers.
56 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure C15. Regional AVO seismograph stations on Unimak Island in 2011. Permanent stations are 

shown by open squares. Closed triangles show volcanic centers.

Figure C16. AVO seismograph stations near Shishaldin Volcano in 2011. Permanent stations are 

shown by open squares. Closed triangles show volcanic centers.
Appendix C 57

Figure C17. AVO seismograph stations near Westdahl Peak in 2011. Permanent stations are shown 

by open squares. Closed triangles show volcanic centers. Solid squares indicate points of interest.

Figure C18. AVO seismograph stations near Akutan Peak in 2011. Permanent stations are shown by 

open squares. Closed triangles show volcanic centers. 
58 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure C19. AVO seismograph stations near Makushin Volcano in 2011. Permanent stations are 

shown by open squares. Closed triangles show volcanic centers.

Figure C20. AVO seismograph stations near Okmok Volcano in 2011. Permanent stations are shown 

by open squares. Closed triangles show volcanic centers. 
Appendix C 59

Figure C21. AVO seismograph stations on Atka Island in 2011. Permanent stations are shown by 

open squares. Closed triangles show volcanic centers.

Figure C22. Regional AVO seismograph stations around Adak Island in 2011. Permanent stations are 

shown by open squares. Closed triangles show volcanic centers.
60 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure C23. AVO seismograph stations near Great Sitkin Volcano in 2011. Permanent stations are 

shown by open squares. Closed triangles show volcanic centers.

Figure C24. AVO seismograph stations near Kanaga Volcano in 2011. Permanent stations are shown 

by open squares. Closed triangles show volcanic centers.
Appendix C 61

Figure C25. Regional AVO seismograph stations around Tanaga Volcano and Mount Gareloi in 2011. 

Permanent stations are shown by open squares. Closed triangles show volcanic centers.

Figure C26. AVO seismograph stations near Tanaga Volcano in 2011. Permanent stations are shown 

by open squares. Closed triangles show volcanic centers.
62 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure C27. AVO seismograph stations near Mount Gareloi in 2011. Permanent stations are shown 

by open squares. Closed triangles show volcanic centers.

Figure C28. AVO seismograph stations on Semisopochnoi Island in 2011. Seismograph station AMKA 

is not shown and is located 65 km south-southwest of Mount Cerberus. Permanent stations are 

shown by open squares. Closed triangles show volcanic centers.
Appendix C 63

Figure C29. AVO seismograph stations on Little Sitkin Island in 2011. Permanent stations are shown 

by open squares. Closed triangles show volcanic centers.
64 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

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Appendix D 65

65

Appendix D. Operational Status for AVO Stations in 2011. 

A solid bar indicates periods of time a station was operational based on station use plots and 

weekly checks. Dashed vertical lines show the beginning/end of each month. 
66 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

66
Appendix D 67

67
68 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

68
Appendix D 69

69
70 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

70

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Appendix E 71

Appendix E. Seismic Velocity Models Used in Locating the Earthquakes in 

2011. 

Following the name of each velocity model is a list of volcano subnetworks for which the model is 

used. Depths are referenced to sea level, with negative values reflecting height above sea level.

 

Cylindrical Model Parameters (Latitude and Longitude are the center of the model). 

Velocity Model Latitude 

(°N)

Longitude

 (°E)

Radius 

(km)

Top 

(km)

Bottom 

(km)

Spurr 61.60 -152.40 20 -3 50

Spurr 61.47 -152.33 20 -3 50

Spurr 61.33 -152.25 20 -3 50

Spurr 61.17 -152.35 20 -3 50

Spurr 61.00 -152.45 20 -3 50

Redoubt 60.83 -152.55 20 -3 50

Redoubt 60.66 -152.66 20 -3 50

Redoubt 60.49 -152.75 20 -3 50

Redoubt 60.34 -152.86 20 -3 50

Iliamna 60.03 -153.09 20 -3 50

Augustine 59.36 -153.42 20 -3 50

Katmai 58.17 -155.35 20 -3 50

Katmai 58.29 -154.86 20 -3 50

Katmai 58.35 -155.09 20 -3 50

Katmai 58.43 -154.38 20 -3 50

Veniaminof 56.18 -159.38 30 -3 50

Cold Bay 55.42 -161.89 20 -3 50

Cold Bay 55.18 -162.27 20 -3 50

Cold Bay 54.76 -163.97 30 -3 50

Westdahl 54.52 -164.65 20 -3 50

Akutan 54.15 -165.97 20 -3 50

Makushin 53.89 -166.92 20 -3 50

Okmok 53.40 -168.16 20 -3 50

Andreanof 52.08 -176.13 20 -3 50

Andreanof 51.93 -176.75 20 -3 50

Andreanof 51.92 -177.17 20 -3 50

Tanaga 51.89 -178.15 20 -3 50
72 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

 Akutan Velocity Model (Power and others, 1996). 

Layer number Vp (km/sec) Top of layer (km) Vp/Vs

1 2.30 +0.37 km/sec for each km of depth -3.0 1.80

2 6.30 7.0 1.80

Andreanof Velocity Model (Toth and Kisslinger, 1984).

Layer number Vp (km/sec) Top of layer (km) Vp/Vs

1 3.50 -3.0 1.73

2 3.88 -2.8 1.73

3 4.25 -2.6 1.73

4 4.62 -2.4 1.73

5 5.00 -2.2 1.73

6 5.50 -2.0 1.73

7 5.62 -1.0 1.73

8 5.74 0.0 1.73

9 5.86 1.0 1.73

10 5.98 2.0 1.73

11 6.10 3.0 1.73

12 6.60 4.0 1.73

13 6.68 5.0 1.73

14 6.80 8.0 1.73

15 6.92 11.0 1.73

16 7.04 14.0 1.73

17 7.16 17.0 1.73

18 7.28 20.0 1.73

19 7.85 23.0 1.73

20 8.05 37.0 1.73

Augustine Velocity Model (Power, 1988).

Layer number Vp (km/sec) Top of layer (km) Vp/Vs

1 2.3 -3.0 1.80

2 2.6 -0.7 1.80

3 3.4 0.0 1.80

4 5.1 1.0 1.80

5 6.3 9.0 1.78

6 8.0 44.0 1.78
Appendix E 73

Cold Bay Velocity Model (McNutt and Jacob, 1986). 

Layer number Vp (km/sec) Top of layer (km) Vp/Vs

1 3.05 -3.00 1.78

2 3.44 0.00 1.78

3 5.56 1.79 1.78

4 6.06 3.65 1.78

5 6.72 10.18 1.78

6 7.61 22.63 1.78

7 7.90 38.51 1.78

Iliamna Velocity Model (Roman and others, 2001). 

Layer number Vp (km/sec) Top of layer (km) Vp/Vs

1 4.8 -3.0 1.78

2 6.1 -1.6 1.78

3 6.2 1.7 1.78

4 6.3 2.9 1.78

5 6.4 3.1 1.78

6 7.1 16.5 1.78

Katmai Velocity Model (Searcy, 2003). 

Layer number Vp (km/sec) Top of layer (km) Vp/Vs

1 5.05 -3.0 1.78

2 5.10 1.0 1.78

3 5.41 2.0 1.78

4 5.49 3.0 1.78

5 5.65 4.0 1.78

6 5.67 5.0 1.78

7 5.69 6.0 1.78

8 5.76 7.0 1.78

9 5.80 8.0 1.78

10 6.00 9.0 1.78

11 6.04 10.0 1.78

12 6.08 12.0 1.78

13 6.30 15.0 1.78

14 6.73 20.0 1.78

15 7.54 25.0 1.78

16 7.78 33.0 1.78
74 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Makushin Velocity Model (Cheryl Searcy, written commun., 2010).

Layer number Vp (km/sec) Top of layer (km) Vp/Vs

1 3.88 -3.0 1.86

2 3.92 0.0 1.88

3 3.99 1.0 1.61

4 4.11 2.0 1.66

5 4.81 3.0 1.70

6 5.40 4.0 1.91

7 5.82 4.5 1.77

8 6.40 5.0 1.70

9 6.53 9.0 1.68

10 6.92 10.0 1.71

11 7.37 11.0 1.82

12 7.68 23.0 1,78

13 8.08 28.0 1.78

Okmok Velocity Model (Masterlark and others, 2010).

Layer number Vp (km/sec) Top of layer (km) Vp/Vs

1 3.830 -3.0 1.73

2 3.891 0.0 1.73

3 5.084 1.0 1.73

4 5.187 2.0 1.73

5 5.470 3.0 1.73

6 6.185 4.0 1.73

7 6.191 10.0 1.73

8 6.454 12.0 1.73

9 6.896 16.0 1.73

10 7.414 20.0 1.73

Redoubt Velocity Model (Lahr and others, 1994). 

Layer number Vp (km/sec) Top of layer (km) Vp/Vs

1 2.90 -3.0 1.80

2 5.10 -1.7 1.80

3 6.40 1.5 1.72

4 7.00 17.0 1.78
Appendix E 75

Spurr Velocity Model (Jolly and others, 1994). 

Layer number Vp (km/sec) Top of layer (km) Vp/Vs

1 5.1 -3.00 1.81

2 5.5 -2.00 1.81

3 6.3 5.25 1.74

4 7.2 27.25 1.78

Tanaga Velocity Model (Power, written commun., 2005). 

Layer number Vp (km/sec) Top of layer (km) Vp/Vs

1 4.0 -3.0 1.78

2 4.5 -1.2 1.78

3 5.0 0.0 1.78

4 5.6 4.0 1.78

5 6.9 10.0 1.78

6 7.2 15.0 1.78

7 7.8 20.0 1.78

8 8.1 33.0 1.78

Veniaminof Velocity Model (Sánchez, 2005). 

Layer number Vp (km/sec) Top of layer (km) Vp/Vs

1 4.82 -3.0 1.73

2 5.23 4.0 1.88

3 5.23 10.0 1.38

4 6.49 15.0 1.65

5 6.52 20.0 1.51

6 8.18 25.0 1.89

7 8.21 33.0 1.90

8 8.21 47.0 1.80

9 8.30 65.0 1.78

Westdahl Velocity Model (Dixon and others, 2005). 

Layer number Vp (km/sec) Top of layer (km) Vp/Vs

1 3.03 -3.0 1.71

2 3.18 0.0 1.71

3 5.03 2.0 1.71

4 5.70 8.0 1.71

5 6.30 10.0 1.71

6 6.82 16.0 1.71

7 7.17 26.0 1.71

8 8.16 38.0 1.71
76 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Regional Velocity Model (Fogleman and others, 1993). 

Layer number Vp (km/sec) Top of layer (km) Vp/Vs

1 5.3 -3.0 1.78

2 5.6 4.0 1.78

3 6.2 10.0 1.78

4 6.9 15.0 1.78

5 7.4 20.0 1.78

6 7.7 25.0 1.78

7 7.9 33.0 1.78

8 8.1 47.0 1.78

9 8.3 65.0 1.78

 
Appendix F 77

Appendix F. Location of Volcanic Zones Modeled Using Multiple Cylinders.

Figure F1. Volcanic zones for the Cook Inlet Volcanoes. Five overlapping cylinders model the Spurr volcanic 

zone. Four overlapping cylinders model the Redoubt volcanic zone. Single cylinders model the Iliamna, 

Augustine, and Fourpeaked volcanic zones. 

Figure F2. Volcanic zone for the Katmai volcanic cluster. The volcanic zone is modeled using four 

overlapping cylinders centered on Mount Martin, Mount Katmai, Mount Griggs, and Mount Steller.
78 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

Figure F3. Volcanic zones for Pavlof Volcano and Mount Dutton. The volcanic zone is modeled using two 

overlapping cylinders centered on Mount Dutton and Pavlof Volcano.

Figure F4. Volcanic zones in the Adak region. The volcanic zones are modeled using cylinders centered on 

Kanaga Volcano, Mount Moffett, and Great Sitkin Volcano.
Appendix G 79

Appendix G. Previous AVO Earthquake Catalogs. 

Earthquake catalog for 1989–present available from the USGS.

1989–90: Power, J.A., March, G.D., Lahr, J.C., Jolly, A.D., and Cruse, G.R., 1993, Catalog of earthquake 

hypocenters at Redoubt Volcano and Mount Spurr, Alaska: October 12, 1989 – December 31, 

1990: U.S. Geological Survey Open-File Report 93-685-A, 57 p. 

1991–93: Jolly, A.D., Power, J.A., Stihler, S.D., Rao, L.N., Davidson, G., Paskievitch, J., Estes, S., and 

Lahr, J.C., 1996, Catalog of earthquake hypocenters for Augustine, Redoubt, Iliamna, and Mount 

Spurr Volcanoes, Alaska: January 1, 1991 - December 31, 1993: U.S. Geological Survey OpenFile Report 96-70, 90 p. 

1994–99: Jolly, A.D., Stihler, S.D., Power, J.A., Lahr, J.C., Paskievitch, J., Tytgat, G., Estes, S., Lockhart, 

A.B., Moran, S.C., McNutt, S.R., and Hammond, W.R., 2001, Catalog of earthquake hypocenters 

at Alaskan Volcanoes: January 1, 1994 - December 31, 1999: U.S. Geological Survey Open-File 

Report 01-189, 202 p. 

URL: http://geopubs.wr.usgs.gov/open-file/of01-189/ (last accessed April 1, 2012) 

2000–01: Dixon, J.P, Stihler, S.D., Power, J.A., Tytgat, G., Estes, S., Moran, S.C., Paskievitch, J., and 

McNutt, S.R., 2002, Catalog of Earthquake Hypocenters at Alaska Volcanoes: January 1, 2000 - 

December 31, 2001: U.S. Geological Survey Open-File Report 02-342, 56 p. 

URL: http://geopubs.wr.usgs.gov/open-file/of02-342/ (last accessed April 1, 2012) 

2002: Dixon, J.P., Stihler, S.D., Power, J.A., Tytgat, G., Moran, S.C., Sánchez, J.J., Estes, S., McNutt, 

S.R., and Paskievitch, J., 2003, Catalog of Earthquake Hypocenters at Alaska Volcanoes: January 

1 - December 31, 2002: U.S. Geological Survey Open-File Report 03-267, 58 p. 

URL: http://geopubs.wr.usgs.gov/open-file/of03-267/ (last accessed April 1, 2012) 

2003: Dixon, J.P., Stihler, S.D., Power, J.A., Tytgat, G., Moran, S.C., Sánchez, J.J., Estes, S., McNutt, 

S.R., and Paskievitch, J., 2004, Catalog of Earthquake Hypocenters at Alaska Volcanoes: January 

1 - December 31, 2003: U.S. Geological Survey Open-File Report 2004-1234, 59 p. 

URL: http://pubs.usgs.gov/of/2004/1234/ (last accessed April 1, 2012)

2004: Dixon, J.P., Stihler, S.D., Power, J.A., Tytgat, G., Estes, S., Prejean, S., Sánchez, J.J., Sanches, 

R., McNutt, S.R., and Paskievitch, J., 2005, Catalog of Earthquake Hypocenters at Alaskan 

Volcanoes: January 1 through December 31, 2004: U.S. Geological Survey Open-File Report 

2005-1312, 74 p. 

URL: http://pubs.usgs.gov/of/2005/1312/ (last accessed April 1, 2012) 

2005: Dixon, J.P., Stihler, S.D., Power, J.A., Tytgat, G., Estes, S., and McNutt, S.R., 2007, Catalog of 

Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2005: U.S. 

Geological Survey Open-File Report 2007-1264, 78 p. 

URL: http://pubs.usgs.gov/of/2006/1264/ (last accessed April 1, 2012)

2006: Dixon, J.P., Stihler, S.D., Power, J.A., and Searcy, Cheryl, 2008, Catalog of earthquake 

hypocenters at Alaskan Volcanoes: January 1 through December 31, 2006: U.S. Geological 

Survey Data Series 326, 78 p. 

URL: http://pubs.usgs.gov/ds/326/pdf/ds326.pdf (last accessed April 1, 2012)
80 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

2007: Dixon, J.P., Stihler, S.D., and Power, J.A., and Searcy, Cheryl, 2008, Catalog of earthquake 

hypocenters at Alaskan Volcanoes: January 1 through December 31, 2007: U.S. Geological 

Survey Data Series 367, 82 p. 

URL: http://pubs.usgs.gov/ds/367/pdf/ds367.pdf (last accessed April 1, 2012)

2008: Dixon, J.P., and Stihler, S.D, 2009, Catalog of earthquake hypocenters at Alaskan Volcanoes: 

January 1 through December 31, 2008: U.S. Geological Survey Data Series 467, 88 p.

URL: http://pubs.usgs.gov/ds/467/pdf/ds467.pdf (last accessed April 1, 2012)

2009: Dixon, J.P., and Stihler, S.D, Power, J.A., and Searcy, Cheryl, 2010, Catalog of earthquake 

hypocenters at Alaskan Volcanoes: January 1 through December 31, 2009: U.S. Geological 

Survey Data Series 531, 84 p. 

URL: http://pubs.usgs.gov/ds/531/pdf/ds531.pdf (last accessed April 1, 2012)

2010: Dixon, J.P., and Stihler, S.D, Power, J.A., and Searcy, Cheryl, 2011, Catalog of earthquake 

hypocenters at Alaskan Volcanoes: January 1 through December 31, 2010: U.S. Geological 

Survey Data Series 645, 82 p. 

URL: http://pubs.usgs.gov/ds/645/ (last accessed April 1, 2012)
Appendix H 81

Appendix H. Selected Papers Published in 2011 Using Data Provided by AVO

Gardine, M., West, M., Werner, C., and Doukas, M., 2011, Evidence of magma intrusion at Fourpeaked volcano, 

Alaska in 2006-2007 from a rapid-response seismic network and volcanic gases: Journal of Volcanology and 

Geothermal Research, v. 200, p. 192-200, doi:10.1016/j.jvolgeores.2010.11.018.

Kilgore, W.W., Roman, D.C., Biggs, Juliet, and Hansen, Roger, 2011, Seismic and geodetic investigation of the 1996-

1998 earthquake swarm at Strandline Lake, Alaska: Geophysical Journal International, v. 186, no. 3, p. 1365-1379, 

doi:10.1111/j.1365-246X.2011.05115.x. 

McNutt, S.R., 2011, Volcanic tremor wags on: Nature, v. 470, no. 7335, p. 471-472.

Roman, D.C., and Power, J.A., 2011, Mechanism of the 1996-97 non-eruptive volcano-tectonic earthquake swarm at 

Iliamna Volcano, Alaska: Bulletin of Volcanology, v. 73, no. 2, p. 143-153, doi:10.1007/s00445-010-0439-7 .

Ruppert, N.A., Prejean, Stephanie, and Hansen, R.A., 2011, Seismic swarm associated with the 2008 eruption of 

Kasatochi Volcano, Alaska: Earthquake locations and source parameters: Journal of Geophysical Research, v. 116, no. 

B00B07, 18 p., doi:10.1029/2010JB007435 .
82 Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011

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Dixon and others— Catalog of Earthquake Hypocenters at Alaskan Volcanoes: January 1 through December 31, 2011—Data Series–730