HR: 1340h
AN: S23A-0224    [Abstracts]
TI: Extreme magnitude earthquakes and their economical impact: The Mexico City case
AU: * Chavez, M
EM: marioch48@yahoo.com
AF: Lab. de Geologie, Dept. TAO, ENS, 24 R. Lhomond, Paris, 75005 France, Metropolitan
AU: Mario, C
EM: marioch48@hotmail.com
AF: Instituto de Ingenieria, UNAM, Apdo. 70-569, Mexico DF, 04510 Mexico
AB: The consequences (estimated by the human and economical losses) of the recent occurrence (worldwide) of extreme magnitude (for the region under consideration) earthquakes, such as the 19 09 1985 in Mexico (Ritchter magnitude Ms 8.1, moment magnitude Mw 8.01), or the one in Indonesia of the 26 12 2004 (Ms 9.4, Mw 9.3), stress the importance of performing seismic hazard analysis that, specifically, incorporate this possibility. Herewith, we present and apply a methodology, based on plausible extreme seismic scenarios and the computation of their associated synthetic accelerograms, to estimate the seismic hazard on Mexico City (MC) stiff and compressible surficial soils. The uncertainties about the characteristics of the potential finite seismic sources, as well as those related to the dynamic properties of MC compressible soils are taken into account. The economic consequences (i.e. the seismic risk = seismic hazard x economic cost) implicit in the seismic coefficients proposed in MC seismic Codes before (1976) and after the 1985 earthquake (2004) are analyzed. Based on the latter and on an acceptable risk criterion, a maximum seismic coefficient (MSC) of 1.4g (g = 9.81m/s2) of the elastic acceleration design spectra (5 percent damping), which has a probability of exceedance of 2.4 x 10-4, seems to be appropriate for analyzing the seismic behavior of infrastructure located on MC compressible soils, if extreme Mw 8.5 subduction thrust mechanism earthquakes (similar to the one occurred on 19 09 1985 with an observed, equivalent, MSC of 1g) occurred in the next 50 years.
DE: 7212 Earthquake ground motions and engineering seismology
SC: Seismology [S]
MN: Fall Meeting 2005