seismic hazard analysis 2
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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
ility
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
bab
ility
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
no. o
f ea
rthq
uake
s >
=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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