HR: 14:50h
AN: S53A-06    [Abstracts]
TI: Triggering Sequence by Static Stress Changes of Large aftershocks of the Niigata-Chuetsu, Japan Earthquake
AU: * Miyazawa, M
EM: linen@rcep.dpri.kyoto-u.ac.jp
AF: Research Center for Earthquake Prediction, Disaster Prevention Research Institute, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 Japan
AU: Mori, J J
AF: Research Center for Earthquake Prediction, Disaster Prevention Research Institute, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 Japan
AU: Iio, Y
AF: Research Center for Earthquake Prediction, Disaster Prevention Research Institute, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 Japan
AU: Shibutani, T
AF: Research Center for Earthquake Prediction, Disaster Prevention Research Institute, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 Japan
AU: Matsumoto, S
AF: Institute of Seismology and Volcanology, Faculty of Science, Kyushu University, Shin'yama, Shimabara, Nagasaki, 855-0843 Japan
AU: Katao, H
AF: Research Center for Earthquake Prediction, Disaster Prevention Research Institute, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 Japan
AU: Ohmi, S
AF: Research Center for Earthquake Prediction, Disaster Prevention Research Institute, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 Japan
AU: Nishigami, K
AF: Research Center for Earthquake Prediction, Disaster Prevention Research Institute, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 Japan
AB: Following the 2004 Niigata-Chuetsu earthquake (M6.8), 4 large aftershocks (M6.3, 6.0, 6.5, 6.1) occurred: three within 40 minutes and one 4 days later. We examine the possibility for this triggering of these large aftershocks by static stress changes. For the close spatial triggering, it is important to have information about the fault geometries, slip distribution, and focal mechanisms. We determine the fault planes orientations from the aftershock distributions. Slip distributions of the main shock and largest aftershock are obtained by seismic waveform inversions of local strong-motion records. Mechanisms for the events are taken from CMT solutions. The temporal variations of Coulomb failure function changes (ΔCFF) are calculated on the fault planes of the large aftershocks before their rupture. Positive ΔCFF values (> 0.5 MPa) are obtained on the fault planes, indicating the possibility that static triggering from the main event and large aftershocks can explain the occurrence of aftershocks.
DE: 7203 Body wave propagation
DE: 7209 Earthquake dynamics and mechanics
DE: 7212 Earthquake ground motions and engineering
DE: 7230 Seismicity and seismotectonics
DE: 8164 Stresses--crust and lithosphere
SC: Seismology [S]
MN: 2005 Joint Assembly