Southwestern U.S. Ground Motion Chrcteriztion Senior Seismic Hzrd Anlysis Committee Level 3 Workshop #2 October 22-24, 2013 A Brief Review on Akkr, Sndikky nd Bommer (ASB13 GMPE Sinn Akkr Deprtment of Civil Engineering, Middle Est Technicl University 06800 Ankr, Turkey
Outline o Overview of ASB13 with emphsis on o Mgnitude dependence of sigm o Reduction in sigm fter 3 seconds o Dependence of residuls on depth o Norml fulting fctors
Mjor fetures of ASB13 o Developed using subset of RESORCE (Reference Dtbse for Seismic- Ground Motion in Europe o Totl number of erthqukes: 221 o Totl number of records: 1041 o Minimum nd mximum response periods: PGA, PGV nd T = 1s T = 4.0s o Horizontl component definition: Geometric men o Distnce metrics: R epi, R hyp nd o Mximum distnce: 200 km o Mximum depth: 30 km o Minimum nd mximum moment mgnitude: M w 4 M w 7.6 o Minimum nd mximum V S30 (ll mesured: V S30 = 92 m/s V S30 = 2165 m/s o Recommended mgnitude, distnce, period nd V S30 intervls: o 4 M w 8 o Distnces up to 200 km o PGA, PGV nd 1s T 4 s o 150 m/s V S30 1200 m/s
Overll distribution of strong-motion dtbse M w 8 7 6 5 4 o 3-component, 1041 recordings with distnces less thn 200 km o 221 erthqukes (MS AS with focl depths less thn 30 km nd M w 4. o Ech event hs t lest 2 recordings o 322 sttions with mesured V S30 vlues. o Mgnitudes up to M w 7 nd distnces > 5 km re well represented
SoF nd V S30 bsed distribution of strongmotion dtbse o Few dt with V S30 > 800 m/s nd V S30 < 180 m/s o Reverse-fulting erthqukes re poorly represented. Most dt come from norml (Itlin nd strike-slip (Turkish events o M w > 7 events re mostly from strike-slip erthqukes
Depth distribution of strong-motion dtbse o Events with M w > 6 hve depths less thn 20 km o Depth distribution is more uniform for M w 6
Functionl Form [ ] [ ] t JB w REF S SoF R M Y Y εσ = ln,, ( ln ln( [ ] [ ] > = 1 9 8 2 6 2 1 5 4 2 3 1 7 1 1 9 8 2 6 2 1 5 4 2 3 1 2 1 ln( ( (8.5 ( ln( ( (8.5 ( ln( c M F F R c M M c M c M F F R c M M c M Y w N R JB W w w w N R JB W w w REF Medin ground-motion for reference rock Site effect Aletory vribility Sinn Akkr 11/07/2013
Style-of-Fulting (SoF fctors o SoF coefficients re found to be sensitive to the distribution of fulting type in the dtbse. o They re obtined by removing the smll events (M w < 5 hving less thn 3 recordings (eliminte the poorly recorded events. N:SS 1.4 1.2 1.0 Firly consistent pttern with CB08 nd AB10 This study AB10BAD12 AS08 BA08 CB08 CY08 1 0.1 1 R:SS 1.4 1.2 1.0 Very complicted ptterns. No model is entirely comptible with the others 1 0.1 1 Period (s Z TOR is ssumed s zero for AS08, CB08 nd CY08 Period (s
Residul nlysis overll trends Between-event Residuls Within-event Residuls Within-event Residuls 1.0 0.5-0.5-1.0 2 1 0-1 -2 2 1 0-1 -2 T = s T = s T = 1.0s T = s 4 5 6 7 8 M w 100 1000 V S30 (m/s T = s 4 5 6 7 8 4 5 6 7 8 M w 100 1000 V S30 (m/s T = 1.0 s M w 100 1000 V S30 (m/s o Dt do not support mgnitude-dependent sigm (sprse dt smpling towrds lrge mgnitudes o No bised estimtions in terms of distnce o Slight overestimtion t very soft sites nd under estimtion for rock sites t short periods (e.g., T = s
Residul nlysis dependence of mgnitude Stndrd devition Between-event residuls (T = s Between-event residuls (T = s 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 Within-event residuls (T = s 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 Within-event residuls (T = s Between-event residuls (T = 1.0s 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 Within-event residuls (T = 1.0s Vrition of stndrd devition seems to be independent of mgnitude for M w 6.5. Stndrd devition 0.7 0.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 0.7 0.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 0.7 0.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 For lrger mgnitudes, the fluctutions cn be misleding s there is fewer dt. M w M w M w
Residul nlysis mgnitude nd SoF dependence
Sigm Mu Sigm Mu Sigm Mu Modeling uncertinty considering mgnitude nd SoF PGA - Strike-Slip Strike-slip PGA - Norml PGA - Reverse 0.3 0.1 1 10 p 100 0.3 0.1 1 10 p 100 0.3 0.1 PGA T=s T=1.0s 0.3 0.1 0.3 0.1 0.3 0.1 0.3 0.1 0.3 0.1 0.3 0.1 M4.0 M4.5 M5.0 M5.5 M6.0 M6.5 M7.0 M7.5 M8.0 o No significnt differences between M4.0 norml M4.5 nd strike-slip M5.0 M5.5 M6.0 erthqukes. M6.5 Modeling M7.0 M7.5 M8.0 uncertinty is higher for reverse events with respect to other two M4.0 SoF M4.5 M5.0 M5.5 M6.0 o More M6.5 relible results M7.0 M7.5 M8.0 between 4.5 M w 6
Residul nlysis depth dependence PGA T = s T = 1.0s - - - Norml Events Reverse Events Strike-Skip Events p = 87 p = 07 p = 0.339 - - - - - - 0 5 10 15 20 25 30 0 5 10 15 20 25 30 0 5 10 15 20 25 30 p = 0.17 p = 11 p = 0.3 - - - - - - - - - - - -1.0-0 5 10 15 20 25 30 0 5 10 15 20 25 30 0 5 10 15 20 25 30 - - - - - - 0 5 10 15 20 25 30 0 5 10 15 20 25 30 0 5 10 15 20 25 30 Depth p = 5 p = 09 p = 8 - - - Depth - - - - - - Depth
Stndrd devition R epi Stndrd devition 1.0 totl within-event between-event 1 0.1 1 Period (s R hyp o Vrition of sigm is lmost period independent except for the portion between 3s nd 4s. o The level of totl sigm is similr to AB10. It is slightly lrger with respect to NGA- W1 GMPEs.
Reduction in stndrd devition fter T = 3s At T = 4s, 36% of ccelerogrms nd 28% of erthqukes re removed due to low-cut filter vlues used in dt processing. 1.0 Dt Loss (in % 40 30 20 10 Accelerogrms Erthqukes Dt loss doubles between T = 3s nd T = 4s Stndrd Devition (for model totl sigm within-event sigm between-event sigm 0 0 1 2 3 4 Period (s Considerble reduction in the dt size for T 3s results in the observed decy in stndrd devitions 1 0.1 1 Period (s
Conclusions 1/3 Mgnitude-dependence of sigm (for lrger erthqukes o Dtbse contins few lrge mgnitude events bove M w 7. Thus, the distribution of dt does not llow estblishing mgnitudedependent sigm. o The vrition of stndrd devition seems to be independent for M w 6.5. o The model uncertinty seems to be less significnt for 4.5 M w 6 for the whole distnce rnge. Influence of depth on ASB13 estimtes o The vrition of between-event residuls in terms of depth indicte tht the bis in norml nd strike-slip ground-motion estimtions is insignificnt with respect to reverse events. The reverse fult ground motions tend to be overestimted with incresing depth.
Conclusions 2/3 How well the estimtes re for different SoF? o SoF coefficients show similrities with CB08 nd AB10 for N:SS rtios. They differ significntly with the compred GMPEs for R:SS rtios. The dtbse is rich in terms of norml nd strike-slip erthqukes. It is believed tht N:SS rtios re stble in our model. o The insignificnt M w -dependent between-event residul trends for N nd SS estimtes indicte better performnce of ASB13 for these fulting mechnisms. The sme performnce is not observed for reverse erthqukes o The model uncertinty lso seems to be less significnt for norml nd strike-slip events. This observtion supports the stbility of N:SS rtios (or stbility of N nd SS SoF coefficients.
Conclusions 3/3 Reduction in sigm fter T = 3.0s o The decrese in number of erthqukes nd ccelerogrms results in sudden drop in sigm fter T = 3.0s. o The within-event sigm seems to be ffected more by the decrese in ccelerogrms fter T = 3s o The reduction in between-event sigm is observed only for T 3.8s due to decrese in event number.
References o Akkr S, Sndikky MA nd Bommer J (2013. Empiricl ground-motion models for point- nd extended-source crustl erthquke scenrios in Europe nd the Middle Est. Bulletin of Erthquke Engineering, DOI 10.1007/s10518-013-9461-4 o Akkr S, Sndikky MA nd Bommer J (2013. Errtum to: Empiricl ground-motion models for point- nd extendedsource crustl erthquke scenrios in Europe nd the Middle Est. Bulletin of Erthquke Engineering, DOI 10.1007/s10518-013-9508-6 o Al Atik L nd Youngs RR (2013. Epistemic uncertinty for NGA-West2 models. Pcific Erthquke Reserch Center, University of Cliforni t Berkeley, PEER Report 2013/11
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