Introduction to Seismology

Seismic Hazard Analysis 2

Department of Earth SciencesKFUPM

Ali Onceloncel@kfupm.edu.sa

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Seismic source characterizationEstimation of seismicity (recurrence) parameters for each sourceSelection of ground motion attenuation modelsQuantification of the seismic hazard

log(N)

M

RECURRENCE

Pro

bab

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of

exce

edance

Acceleration

SEISMICHAZARDCURVES

F2

F1

Faults(line sources)

Area source

SOURCEMODELS

pga,

Sa, A

i

GROUND MOTION ATTENUATION

distance

SEISMIC HAZARD MAP

Sari and Manuel

Probabilistic Seismic Hazard AnalysisIn

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PART 1: SOURCE CHARACTERIZATION

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From Koji Okumura

Rupture zones for large historical earthquakes along the North and East Anatolian faults (Ambraseys & Finkel, 1988; Ambraseys & Finkel, 1995; Barka, 1992; Ikeda et al., 1991)

from

1254

967

17841668

10351050 1043

From Koji Okumura

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Both wallseast west

First multi-event trench on the North Anatolian fault

Koji Okumura

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Time Dependent Probability for Cascadia Subduction Zone

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.0 0.5 1.0 1.5 2.0 2.5

Return period

50-y

ear

pro

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BPT500

LOGNORMAL500BPT600

BPT400

BPTa=0.21

BPTa=1.0

BPTa=1.25

Poissonian

CurrentTime (300/500)

BPT a=0.21, M=500

BPT a=0.5, M=400

BPT a=0.5, M=500Lognormal a=0.5,M=500

BPT a=0.5, M=600

PoissonianBPT a=1.0, M=500

BPT a=1.25, M=500

Magnitude area relations

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Magnitude scales:Body wave magnitude (Mb)Richter magnitude (ML)Surface wave magnitude (Ms)Moment magnitude (Mw)

Catalogs:Preliminary Determination of Earthquakes (PDE)International Seismic Centre (ISC)Local catalogs (Ambraseys)

EARTHQUAKE CATALOGSIn

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Magnitude saturation

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NEIC: Earthquake Search Results

Rectangular Grid Search Latitude Range: 39 to 41.5 Longitude Range: 27.25 to 31 Number of Earthquakes: 3468  

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•Development of one catalog from several catalogs•Declustering•Use of Catalog•Calculation of Gutenberg-Richter a and b-values•Smooth seismicity model (background)•Comparison with model rates of seismicity

Developing uniform catalog:In

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1. Characteristic a. Assess magnitude of potential earthquakes (segmentation, floating)b. Calculate recurrence of earthquake= moment of char earthquake/moment rate of fault= rigidity*area*displacement/rigidity*area*slip raterigidity modulus (resistance to shearing motion used in U.S. is 3.0 X 10exp11 gm/cm*s*s(dynes/cm*cm)2. Truncated Gutenberg-Richter distribution a. log N=a-b M

Log

of

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rthq

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=M

Magnitude (M) Magnitude (M)

CharacteristicGutenberg-Richter

MAGNITUDE FREQUENCY DISTRIBUTIONS

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Assumes that where smaller magnitude earthquakeshave occurred in the past is where larger earthquakes will occur in the future.

Smoothed SeismicityIn

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Quiz of the Week

For Central Arabian Graben Zone, seismicity parameters are given as:

a=4.02b= 0.65Mmax=6.2

Considering the regional maximum magnitude (6.2), calculate

The frequency of M6.2? The recurrence period of M6.2?Earthquake Probability of M6.2 for 50 yrs?

P(t)= 1-e-t/T

Equations

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