HR: 1340h
AN: S13C-1437    [Abstracts]
TI: PreSEIS: Earthquake Early Warning for Finite Faults
AU: * Böse, M
EM: maren.boese@gpi.uni-karlsruhe.de
AF: Geophysical Institute, Karlsruhe University, Hertzstrasse 16, Karlsruhe, 76187, Germany
AU: Wenzel, F
EM: friedemann.wenzel@gpi.uni-karlsruhe.de
AF: Geophysical Institute, Karlsruhe University, Hertzstrasse 16, Karlsruhe, 76187, Germany
AU: Erdik, M
EM: erdik@boun.edu.tr
AF: Kandilli Observatory and Earthquake Research Institute, Bogazici University, Department of Earthquake Engineering, Istanbul, 34684, Turkey
AB: Earthquake early warning (EEW) systems have to meet two requirements: they have to be both fast and highly reliable. We have developed a method for EEW, called PreSEIS, which is as quick as methods that are based on single station observations and, at the same time, shows a higher robustness than most other approaches. At regular time steps after the triggering of the first EEW sensor, PreSEIS estimates the most likely source parameters of an earthquake using the available information on ground shaking at different sensors in a seismic network. The approach is based on two-layer feed-forward neural networks that allow estimating the location of the earthquake hypocenter, its moment magnitude, and the expansion of the evolving seismic rupture. We apply PreSEIS to the Istanbul Earthquake Rapid Response and Early Warning System (IERREWS). The moment magnitudes of 280 simulated finite faults scenarios (4.5 <= M <= 7.5) are estimated with errors of less than +-0.8 units after 0.5 s, +-0.5 units after 7.5 s, and +-0.3 units after 15.0 s. The mean location errors can be reduced in the same time intervals from 10 km over 6 km to less than 5 km, respectively. Our analysis demonstrates that the uncertainties of the estimated parameters (and thus of the warnings) decrease with time. This reveals a trade-off between the reliability of the warning on the one hand, and the remaining warning time on the other hand. The regular up-date of predictions with time allows PreSEIS to handle complex ruptures, in which the largest fault slips do not occur close to the point of rupture initiation. The estimated expansions of the seismic ruptures lead to a clear enhancement of alert maps, which visualize the level and distribution of likely ground shaking in the affected region seconds before seismic waves will arrive.
DE: 7200 SEISMOLOGY
DE: 7299 General or miscellaneous
SC: Seismology [S]
MN: 2007 Fall Meeting