Ground Motions Simulations of the 2004 Les Saintes Earthquake (Mw 6.4) and its Largest Aftershock (Mw 5.9)
Abstract
The Guadeloupe Island situated in the Caribbean arc has been struck in November 2004 by a Mw 6.4 earthquake that occurred 20km offshore on a shallow crustal fault. This event caused the death of one person and serious damages to several buildings. The mainshock has been followed by a large number of aftershocks including about 20 events of magnitude larger than 4. The largest aftershocks occurred three month after the mainshock and reached a magnitude Mw 5.9. Most of the earthquake larger than 4 were well recorded by an accelerometric network situated on the nearby islands (the RAP network locally managed by IPGP and BRGM). Data from these stations are available freely on the web site of the RAP network (www-rap.obs.ujf-grenoble.fr). We used the recordings of ten earthquakes of magnitude 4 to 5.2 successively as empirical Green's functions to generate accelerograms for the mainshock and the largest aftershock at 13 stations. For each small event chosen as empirical Green's function, we simulated 500 accelerometers at each station using a two step stochastic approach (Kohrs-Sansorny et al, 2005, BSSA). We compared the results obtained with the signals recorded. We show that, if the parameter C (static stress drop ratio between the mainshock and the aftershock) is properly chosen, this method enables us to generate simulations that fit well the observed signals. We obtained particularly a good reproduction of site effects. This is true for almost all the small event taken as empirical Green's function, as if they are relatively far away from the mainshock. The choice of the parameter C is discussed in this paper by a comparison of the results obtained on rock stations and the values predicted by ground motion prediction equations.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- Bibcode:
- 2007AGUFM.S11A0278C
- Keywords:
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- 7212 Earthquake ground motions and engineering seismology