Variation of repeating earthquake activities depending on their focal depths as inferred from 3-D numerical simulations

HR: 11:50h
AN: S12B-07 [Abstracts]
TI: Variation of repeating earthquake activities depending on their focal depths as inferred from 3-D numerical simulations
AU: * Ariyoshi, K
EM: ariyoshi@jamstec.go.jp
AF: Department of Oceanfloor Network System Development for Earthquakes and Tsunamis (DONET), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 3173-25 Showa-machi, Kanazawa-ku Yokohama, 236-0001, Japan
AU: Matsuzawa, T
EM: matuzawa@aob.geophys.tohoku.ac.jp
AF: Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Aoba 6-6, Aramaki, Aoba-ku Sendai, 980-8578, Japan
AU: Hino, R
EM: hino@aob.geophys.tohoku.ac.jp
AF: Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Aoba 6-6, Aramaki, Aoba-ku Sendai, 980-8578, Japan
AU: Hasegawa, A
EM: hasegawa@aob.geophys.tohoku.ac.jp
AF: Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, Aoba 6-6, Aramaki, Aoba-ku Sendai, 980-8578, Japan
AU: Hori, T
EM: horit@jamstec.go.jp
AF: Department of Oceanfloor Network System Development for Earthquakes and Tsunamis (DONET), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 3173-25 Showa-machi, Kanazawa-ku Yokohama, 236-0001, Japan
AU: Kaneda, Y
EM: kaneday@jamstec.go.jp
AF: Department of Oceanfloor Network System Development for Earthquakes and Tsunamis (DONET), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 3173-25 Showa-machi, Kanazawa-ku Yokohama, 236-0001, Japan
AB: We investigated depth dependence of the slip velocity of small repeating earthquakes using 3-D numerical simulations for a subduction zone involving large and small asperities based on a rate- and state-dependent friction law. In this study, we examined slip at small asperity located at depth of 5, 10 and 15 km. Our results reveal that the postseismic slip of a large earthquake trigger “slow” slip (with slip velocity lower than that of the spontaneous rupture of the small asperity) rupture of the small asperity located at a depth of 15 km, whereas “rapid” slip (with higher slip velocity) one at a depth of 5 km where the small asperity usually occur slow repeating earthquakes. In case of the small asperity at a depth of 10 km, all of events are seismic and recurrence intervals are temporally shorter in the passage of postseismic slip. Uchida et al. [2003; GRL] showed that the repeating earthquakes in the NE Japan subduction zones occur constantly, conforming with the rate of the plate convergence in the depth range of > ~40 km. On the other hand, shallow (< ~10 km) focus repeating earthquakes tend to be activated only in the postseismic period of nearby large interplate earthquakes and cumulative slip estimated from them is less than that expected from the plate convergence rate. In general, asperities in the shallower part are more stable than deeper ones because of low effective normal stress. Thus, most of the observed shallow repeating earthquakes may be “rapid” slip events triggered by the postseismic slip of the neighboring large asperities, and the corresponding small asperities give rise to (aseismic) slow slip events usually.
DE: 7215 Earthquake source observations (1240)
DE: 7219 Seismic monitoring and test-ban treaty verification
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7240 Subduction zones (1207, 1219, 1240)
SC: Seismology [S]
MN: 2007 Fall Meeting