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ATTENUATION RELATIONS OF STRONG ATTENUATION RELATIONS OF STRONG MOTION IN JAPAN MOTION IN JAPAN
USING SITE CLASSIFICATION BASED ON USING SITE CLASSIFICATION BASED ON PREDOMINANT PERIODPREDOMINANT PERIOD
Toshimasa TakahashiAkihiro AsanoTaketoshi Saiki
Hidenobu OkadaKojiro IrikuraJohn X. ZhaoJian Zhang
Hong K. ThioPaul G. Somerville
Yasuhiro FukushimaYoshimitsu Fukushima
2002 OECD/NEA Istanbul
Bridge between Seismology and Engineering
2003 IEAE Vienna
Semi-empirical Green’s function estimation of kinematical-base was applied to seismic evaluation of an existing nuclear facility.
Current from empirical estimation to physical modeling
2004 OECD/NEA Tsukuba
Empirical estimation based on observation can be still useful.
Estimation of strong ground motionDynamics
Theoretical
Dislocation in elastic medium simulating by
kinematics
1
10
100
1000
10000
1 10 100 1000’ f‘ w‚ ©‚ ç‚ Ì‹ ——£ (km)
�ő
å‰Á‘
¬“x(c
m/s
/s)
SoilRock
Rock� |ƒ Ð
Soil� {ƒ Ð
Semi-empirical Empirical
Large motion is synthesized using
small records.
Attenuation relation is determined by
regression analysis of SMDB.
2003 Bam, Iran earthquake
Closest distance from fault (km)
Peak
Gro
und
Acc
eler
atio
n (c
m/s
/s)
ModelingAcquisition of accurate parameters is required.Dynamic
Kinematics
Semi-empirical Green’s function
Attenuation relation
Reflecting characteristics of observed strong motion
Confirmation of derived result
Stress3-D geologyetc.Hybrid
Physical knowledgeEmpirical
Large amount of data exists already.
(NIED etc.)
Dataset used in the present studyDataset used in the present study
Total 4726 data (average of 2 horizontal) from 270 events
Functional form of the attenuation Functional form of the attenuation relationrelation used in the present studyused in the present study
The functional form of attenuation models
i – earthquake numberj – station numberM – magnitudex – source distance h – focal depthhc – depth constantδh – dummy variable
)iexp(dMc +ji,xji,r =
η + ξ + S +S +S +S +δ )h(he + ) log( -x b -Ma = (T)]Y[(log iji,kSIRhcji,ji,iji, r −
SR – reverse fault term for crustal eventsSI – interface event termSS – Slab event termξ – intra-event error η – inter-event errorSk – site term
Site class definitions used in the present Site class definitions used in the present study and the approximately study and the approximately
corresponding NEHRP site classes corresponding NEHRP site classes
Site class Site natural period (s)
Average shear-wave velocity
NEHRP class
SC I: (Rock/stiff soil) TG < 0.2s V30 > 600 m/s A+BSC II: ( Hard soil) 0.2s £ TG < 0.4s 300 m/s < V30 £ 600 m/s CSC III: (Medium soil) 0.4s £ TG < 0.6s 200 m/s < V30 £ 300 m/s DSC IV: (Soft soil) TG ³ 0.6s V30 £ 200 m/s E
Site natural period - four times the S wave travel time (1-D)
Mean H/V ratios and standard errors Mean H/V ratios and standard errors from a subset of Kfrom a subset of K--net stationsnet stations
Mean H/V ratios for four site classes
Individual site terms divided by SCI
Intra-event residuals distribution
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2
ln(Vs/700)
Intr
a-ev
ent r
esid
uals
1.0s1.5s2.0s� üŒ ̀(1.0s)� üŒ ̀(1.5s)� üŒ (̀2.0s)
Intra-event residuals of hard rock site, Vs over 1000m/s
1
10
100
1000
0.01 0.1 1 10Period (s)
Pseu
do-V
eloc
ity (c
m/s
)
NS 1715 cm/s2
EW 849 cm/s2
Comparison between observed and predicted spectra of main shock on 23 October. NIG021, reverse type and 15.5km from 3rd GSI fault model
Comparison between observed and predicted spectra of main shock on 23 October. NIG019, reverse type and 7.6km from 3rd GSI fault model
NS 1146 cm/s2
EW 1309 cm/s2
1
10
100
1000
0.01 0.1 1 10Period (s)
Pseu
do-V
eloc
ity (c
m/s
)
J MA EW
Energy is released from surface.
Energy propagated in sediment.
Surface break Blind
conclusions
• Empirical attenuation relation can be used to evaluate strong motion level with known uncertainty and to confirm physical models.
• Predominant period corresponding to site geology such H/V is an effective classification parameter.
• Source type segregating improves prediction of strong ground motion.