HR: 16:45h
AN: S34A-04    [Abstracts]
TI: Do Surface Fault Ruptures Cause More Destruction of Houses?
AU: * Tsai, Y
EM: ybtsai@geps.gep.ncu.edu.tw
AF: Institute of Geophysics, National Central University, 300 Jung-Da Road, Chung-Li, 320 Taiwan
AU: Yu, T
EM: ytm545188@yahoo.com.tw
AF: Institute of Geophysics, National Central University, 300 Jung-Da Road, Chung-Li, 320 Taiwan
AU: Lee, C
EM: cplee@geps.gep.ncu.edu.tw
AF: Institute of Geophysics, National Central University, 300 Jung-Da Road, Chung-Li, 320 Taiwan
AB: Surface fault ruptures accompanying large earthquakes are commonly thought to cause more destruction of houses. In some regions such as California, Utah, and Taiwan, formal regulations are put in place to restrict building of houses on land with known surface fault ruptures. However, the question of whether surface fault ruptures do actually cause more destruction of houses has never been checked by empirical data. In this paper, we use the spatial distribution of the percentage of totally collapsed houses from two destructive earthquakes in central Taiwan to address this question. The first earthquake took place on April 21, 1935 with a magnitude of 7.1. The earthquake was accompanyed by two segments of surface fault ruptures, the NE-SW striking right lateral strike-slip Tun-tze-chiao fault and the N-S striking reverse Shih-tan fault. The second earthquake took place on September 21, 1999 with a magnitude 7.6. The earthquake was acompanyed by the N-S striking thrust Chelungpu fault. We first obtained the percentage of houses totally collapsed as well as the percentage of people killed in each village (­Tsun-li­", the smallest administrative district). Then we plot the data on a map to show the spatial distribution patterns of houses collapsed and people killed. The results are summarized as follows: Fault Zone Houses collapsed People killed 1935 Surface ruptures 58.67% 5.85% Tun-tze-chiao S-E side 46.16% 1.82% (Strike-slip ) N-W side 28.47% 1.04% 1935 Surface ruptures 62.19% 1.89% Shih-tan East side 77.21% 0.46% (Reverse) West side 81.59% 1.52% 1999 Surface ruptures 14.54% 0.24% Chelungpu East side 29.41% 0.55% (Thrust) West side 9.73% 0.11% We can see from the table that the surface fault ruptures of the strike-slip Tun-tze-chiao fault did cause more destruction of houses than the outside zones, respectively. In contrary, the surface fault ruptures of the reverse-slip Shih-tan fault and the thrust Chelungpu fault did not cause more destruction of houses than the outside zones. Thus, the building code regulation to restrict building of houses on land with surface fault ruptures apparently is warranted for strike slip faults, but is not necessarily warranted for reverse and thrust faults.
DE: 7223 Seismic hazard assessment and prediction
DE: 6615 Legislation and regulation
DE: 7200 SEISMOLOGY
SC: Seismology [S]
MN: 2004 AGU Fall Meeting