HR: 0830h
AN: S41C-0091    [PDF]
TI: Lessons on Seismic Hazard Estimation from the 2003 Bingol, Turkey Earthquake
AU: * Nalbant, S S
EM: ss.nalbant@ulster.ac.uk
AF: University of Ulster, Geophysics Research Group, School Of Environmental Science, Coleraine, BT52 1SA United Kingdom
AU: Steacy, S
EM: s.steacy@ulster.ac.uk
AF: University of Ulster, Geophysics Research Group, School Of Environmental Science, Coleraine, BT52 1SA United Kingdom
AU: McCloskey, J
EM: j.mccloskey@ulster.ac.uk
AF: University of Ulster, Geophysics Research Group, School Of Environmental Science, Coleraine, BT52 1SA United Kingdom
AB: In a 2002 paper the stress state along the East Anatolian Fault Zone (EAFZ) was estimated by the addition of long term tectonic loading to the static stressing effect of a series of large historical earthquakes. The results clearly indicated two areas of particular concern. The first extended along the EAFZ between the cities of Kahraman Maras and Malatya and the second along the trend of the EAFZ between the cities of Elazig and Bingol. The Bingol (M6.4, 1 May 2003) earthquake occurred within this second area with a focal mechanism which was consistent with left lateral rupture of a buried segment of the EAFZ, prompting suggestions that this represented a success for the idea of using Coulomb Stress Modelling to assess seismic hazard. This success, however, depended on the confirmation of the orientation of the earthquake fault; in the event, and in the absence of surface ruptures, aftershock distributions unambiguously showed that the event was a right lateral failure on an unmapped structure conjugate to the EAFZ. The Bingol earthquake was, therefore, not encouraged by the stress field modelled in the 2002 study. Here we reflect on the lessons learned from this case. We identify three possible reasons for the discrepancy between the calculations and the occurrence of the Bingol earthquake. Firstly, historical earthquakes used in the 2002 study may have been incorrectly modelled in either size or location. Secondly, earthquakes not included in the study, due to either their size or occurrence time, may have had a significant effect on the stress field. Or, finally, the secular stress used to load the faults was inappropriate. We argue that it is through a combination of historical seismology guided and constrained by structural geology, directed paleoseismology and coupled with stress modelling which has been informed by detailed GPS data that an integrated seismic hazard program might have the best chance of success.
DE: 7221 Paleoseismology
DE: 7223 Seismic hazard assessment and prediction
DE: 7230 Seismicity and seismotectonics
SC: Seismology [S]
MN: 2003 Fall Meeting