The 3rd Annual Trilateral of the Strategic Chinese-Korean-Japanese Cooperative Program:Seismic Hazard Assessment for the Next Generation Map, June 16-19, 2013, Sendai, JapanLogic Trees for Probabilistic Seismic
Hazard Analysis in low Seismological
Hazard Zone
Tang Aiping1,2

Tao Xiaxin1

1.School of Civil Engineering, Harbin Institute of Technology

tangap@hit.edu.cn
2. 1.School of Civil Eng. and Env. Eng., Rensselaer Polytechnic
Institutetanga3@rpi.edu

Outlineu What is Logic Tree and Why is it

used in PSHA
u Construction of Logic Tree for PSHA

in low seismological province(LSP)u How to build the Logic Tree for LSPu Conclusions

Part One
What is Logic Tree and Why is it usedin PSHA

What is Logic Treea)

R.B.Kulkarni,R.R. Youngs, K.J.Coppersmith(1984)—8th WCEE,
first introduced the logic tree in PSHA as a tool to capture andquantify the uncertainties related to PSHAb)

A logic tree in PSHA is described as that all steps in which there
are uncertainties to calculate the seismic hazard analysis areseparated branches ,each branches are added for each of thechoices that the analyst considers feasible, and a normalized
weight is assigned to reflect the analyst’s Confidence in choice ofthe most correct model or best estimation. The hazard calculation
are then performed following all the possible branches.

Why is it used in PSHAØ Uncertainty in PSHA (R.J.Budnitz,1997,
Senior Seismic Hazard Analysis Committee ,SSHAC,1997).)

l epistemic uncertainty: incomplete knowledge (lack of data)—

aleatory uncertainty: inherent randomness of groundmotion generation, propagations

u Typical works: 2002 Working Group on California EarthquakeProbabilities, Seismic HAzard haRmonization in Europe(SHARE)
project 2009

Ø PSHA – Logic Tree Methodology—To estimate the epistemic uncertainty.

—A simple mixture of models (probability distributions).

—

Weighting factors based on expert opinions or special
approaches

Logic tree in PSHA

Tectonic model

Seismology model

The hazard calculations are followed all the possible branches through the logic tree,
each analysis producing a single hazard curve showing ground motion against annual
frequency of exceedance. The weighting of each hazard curve is determined bymultiplying the weights along all the component branches.

Part Two
Construction of Logic Tree for PSHA in
low seismological province(LSP)Basic databasep Geology database--- Continental dynamic, tectonic, , rock and stratum,
topography, historic earthquake events, site conditionp Analyzing model database---Seismic source model, Rupture model, Propagation
and attenuation model, site response model, etc.

pExpects system database----Geology, Seismology, Earthquake Engineering, Civil
engineering, Mathematics (model, selection andweighting of Logic tree, criterion )A procedure of Logic tree forGMPE

Part Three
One example of Logic Tree for PSHA
in low seismological province(LT-LSP)

Framework on LT-LSP
Database

Calculation

Hazard Calculation
based on Logic tree
approachResults
Seismic source
Mechanism

seismologicaldatabase

Geographic informationsystem(GIS)
Models database

Expects database

Ground-motion
prediction

Logic tree
construction

One Illustration of LT-LSP
u Geology database----Continental dynamic,

tectonic system, active fault , GPSmonitoring......
u Seismological database---Earthquake

events(historic and device records), Microtremors, M-T, artificial explosion.....
u Models database--- Probability models,Potential seismic source and Seismic Source,
GMPE, Site response......

Geology database in GISBouguer gravity anomaly and deep-fault system

Buried active fault

研究区范围

Fault and volcano

Boring data,
stratum profilein active fault

2260 observation stations,
260 consecutive stations

Seismological database-Isoseismic map(Ms=6.7,1631, Changde)
20 earthquake events Ms> 4.7

Earthquake events in Hunan
Pro.
— Ms<4147— 4≤Ms≤4.5
43— >4.5
24

Magnitude and total number based on three datum

Continental deformation and earthquake
eventsModels database— Potential seismic source area models--- tectonic model, seismological model, Hybrid model— Earthquake source models—empirical models,
New hybrid models( observed data and simulation data), earthquake
observed model, etc— Magnitude distribution models— Ground motion prediction models---Tao,
Gao, Chen, Yu, Abrahamson and Silva, Boore, Campbell and Bozorgnia,
Chiou and Youngs, Irikura, Si, Kanno, Idriss, Scherbaum, etc.

— Site response models—linear models, nonlinearmodels

Average: 2.18, Standard Deviation: 0.15

Earthquake events distribution modelResults

fault rupture modeling

Attenuation Relationship of Spectrum Acc.

Intensity attenuation model in different division based hybrid data

Intensity attenuation model for different expects

PSA attenuation model for different expects

PGA distribution based on Logic tree methedConclusions
Ø Although it is now common practice to treat uncertainty in seismic hazard
analysis with a logic tree approach, there is no standard procedure thatdescribes how the tree should be constructed. Herein, we shared ourexperience on this subject by presenting the strategy that was adopted tobuild a logic tree for Low seismological province. As the greater magnitude,
the much more uncertainty
Ø Gathering as much knowledge and Data as possible from independentsources and different methods, and Logic tree method can capture theepistemic uncertainties and do a sensitivity analysis to check the impact on
the seismic hazard
Ø Expects including multidisciplinary are a good way to get and deal withepistemic uncertainties
Ø GIS is a powerful tool to set up a Logic tree for PSHAThanks for yourattentions !
Questions and comments ?