HR: 1400h
AN: S43A-01    [Abstracts]
TI: Statistical seismology helps to constrain fault plane characteristics: New aspects of the Mw=6.9 Cariaco earthquake
AU: * Sobiesiak, M
EM: polar@gfz-potsdam.de
AF: GFZ Potsdam Section 2.1, Telegrafenberg, Potsdam, 14473, Germany
AU: Heidbach, O
EM: oliver.heidbach@gpi.uni-karlsruhe.de
AF: University of Karlsruhe Institute of Geophysics, Hertzstrasse 16, Karlsruhe, 76187, Germany
AU: Grosser, H
EM: gros@gfz-potsdam.de
AF: GFZ Potsdam Section 2.1, Telegrafenberg, Potsdam, 14473, Germany
AB: The spatial distribution of the seismological parameter b obtained from the Gutenberg-Richter relation can map out changes in the state of stress and/or material properties. This dual capability of the seismic b-value has been utilized in laboratory experiments and seismotectonic studies to infere fault structures which can influence earthquake rupture initiation and propagation. The local b-value study we performed using the aftershock sequence of the 1997, Mw=6.9 earthquake of Cariaco- Casanay in North-eastern Venezuela determines the heterogeneity of the rupture plane and indicates areas of high co-seismic moment release and stress drop. Our new contribution is a slip distribution from a 3D finite element model of the co-seismic rupture. A best fit model is obtained by taking as independent constraints the co-seismic slip observed by 3 GPS stations. Correlating b-value map and slip distribution shows a clear coincidence of high post-seismic b-value patches with areas of large co-seismic slip. We further examined radiated seismic energy and focal mechanisms of aftershocks to look for evidences on fault plane segmentation and took previous local tomography studies as a reference for changes in material properties. In our presentation we will give an interpretation of the observed parameter distributions and correlations along the rupture plane in terms of source characteristics and rupture propagation. First results seem to favour a bi- lateral co-seismic rupture propagation.
DE: 7209 Earthquake dynamics (1242)
DE: 7215 Earthquake source observations (1240)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
SC: Seismology [S]
MN: 2007 Joint Assembly