Scenario Earthquake Shaking Mapsin Japan
Nobuyuki Morikawa
National Research Institute for Earth Science andDisaster Prevention (NIED), JAPANExample of SESMs
The Kego fault zone (south-east part)・・・ The first application of the revised-version of ‘Recipe’Characterized source model
Fault length (L) by the long-term evaluation ⇒ Outer source parameters(Added to the revised-version of ‘Recipe’)
FormulaeM = (log L +2.9) / L(4) log M0 = 1.17・M + 10.72(2)’ S = 2.23・10-15・(M0×107)2/3 (M≧7)(3)’ S= 4.24・10-11・(M0×107)1/2 (M<7)(5) W = S / L(6) Lmodel = S / Wmodel(7) Smodel = Lmodel・Wmodel

Characterized source model
Outer source parameters ⇒ Inner source parameters
For details, see ‘Recipe’(http://www.j-shis.bosai.go.jp/map/JSHIS2/text/news_en.html)

Deep sediments structure model
Seismic bedrock (Vs=3.1 km/s) ～ engineering bedrock (Vs = 0.6 km/s)(Vs=1.1km/s)(Vs=1.4km/s)(Vs=1.7km/s)(Vs=2.1km/s)(Vs=2.7km/s)(Vs=3.1km/s)

Results-1
Peak velocity distribution on the engineering bedrock・ peak velocities atnear source fault incases 1a and 1b arelarger than cases 2aand 2b・ large peak velocity
region extends tosoutheastern of thesource fault in cases 1band 2b(forward directivity
effect andamplifications bysediments)

Results-2

Comparison of calculated peak velocity on the engineering bedrockwith an empirical attenuation relation by Si and Midorikawa (1999)
・ Calculated peakvelocities have atendency small
compared with theattenuation relation. The
depth to seismic bedrockis shallow (200m orless) at most of thecalculated region.

・ Forward directivity
effect and amplifications
by sediments causes
some large velocities incases 1b and 2b.

Results-3
Examples of velocity waveforms on the engineering bedrock(point A: Locate just on the source fault)○ cases 1a & 1b (1 asperity model)
large amplitudes with short duration○ cases 2a & 2b (2 asperities model)
relatively small amplitudes with long
duration

Results-4
Examples of velocity waveforms on the engineering bedrock(point C: Located in a direction extending from the source fault)○ cases 1a & 2asmall amplitudes○ cases 1b & 2blarge pulse with period of about 3s(forward directivity effect+ amplification by sediments)

Results-5
Examples of velocity waveforms on the engineering bedrock(point E: Located on very thick sediments)○ all cases
remarkable later phases with large
amplitudes and periods of 5s○ cases 1b & 2b
relatively large amplitude(forward directivity effect)Calculation of JMA seismic intensity(IJMA) on the ground surfaceWaveforms on theengineering bedrock

Engineering
geomorphologic
classification
Average S-wave
velocity up to 30m
depth (AVS30)

IJMA on the engineering
bedrock

Amplification factor
for peak velocity

Relation between
peak velocity and IJMA

Site amplification factor
for IJMA

IJMA on the groundsurface

Consideration of surface structure(engineering bedrock ～ ground surface)Surface structure modelEngineering
geomorphologic
Classification(Wakamatsu &Matsuoka, 2008)

AVS30(Matsuoka &Wakamatsu,2008)

Amplification
factor for peakvelocity(Fujimoto &Midorikawa, 2006)

Site amplification factor for IJMA
from engineering bedrock (Vs=0.6km/s)
to the ground surface

Results-6
JMA seismic intensity distribution on the ground surface

・ Large amplification
in basins causes verylarge JMA seismic
intensity on the groundsurface for all cases.
・ Difference between
basin and mountainregions is more
remarkable comparedwith peak velocity on
the engineering
bedrock.
IJMA

Conclusions
Scenario Earthquake Shaking Maps
・・・can understand strong ground motion distribution if the target
earthquake occurs,・・・are considered the influences of the rupture processes of thesource fault and detail underground structure, especially the deep
sedimentary layers structure.
Problems remain:・ It is not enough to consider uncertainties in strong-motion
evaluations because only one or few cases are carried out for a target
major active fault.
・The underground structure models should be improved much more.
・SESMs for large subduction-zone earthquakes are also required.
・Forward directivity effect may be overestimated because simple
rupture propagation (circular rupture propagation with a constantrupture velocity) is assumed in the simulation.

Thank you for your attention !