HR: 0800h
AN: S51D-1046    [Abstracts]
TI: Foreshock Characteristics in the Taiwan area
AU: * Yeh, Y
EM: yehyh@earth.sinica.edu.tw
AF: Institute of Earth Sciences, Academia Sinica, P O Box 1-55, Nankang, Taipei, 115 Taiwan
AU: Lin, C
EM: lin@earth.sinica.edu.tw
AF: Institute of Earth Sciences, Academia Sinica, P O Box 1-55, Nankang, Taipei, 115 Taiwan
AB: Foreshocks are often considered as an important precursor in the short-term earthquake prediction. How to identify foreshocks is one of the fundamental problems for applying foreshocks as an earthquake precursor. To improve the understanding of the foreshock characteristics, we have examined 161 earthquakes with a magnitude of greater than 5 in the Taiwan area during the period between 1990-2005. Among them, we found 10 earthquakes with felt foreshocks with a magnitude of greater than 4 occurred within a distance of 15 km and 5 days to the main shock. Those foreshocks were often occurred at strongly shallow crust, particularly along the plate boundary between the Eurasian and Philippine Sea plates. It means the foreshocks were often occurred in the area where the crustal heterogeneity was strong. Besides, detailed analyses of the spatial and temporary variations of three larger earthquake sequences with a magnitude of greater than 5.7 have shown that there was no clustered earthquake after the felt foreshocks. The absence of clustered earthquakes after the felt foreshocks provides a possibility to distinguish foreshocks from the main shock.
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
SC: Seismology [S]
MN: Fall Meeting 2005