Japan Geoscience Union Meeting 2016

Presentation information

Oral

Symbol S (Solid Earth Sciences) » S-SS Seismology

[S-SS27] Fault Rheology and Earthquake Physics

Wed. May 25, 2016 3:30 PM - 5:00 PM Convention Hall A (2F)

Convener:*Takeshi Iinuma(National Research and Development Agency Japan Agency for Marine-Earth Science and Technology), Yuko Kase(Geological Survey of Japan, AIST), Ryosuke Ando(Graduate School of Science, University of Tokyo), Wataru Tanikawa(Japan Agency for Marine-Earth Science and Technology, Kochi Instutute for Core Sample Research), Hideki Mukoyoshi(Department of Geoscience Interdisciplinary Graduate School of Science and Engineering, Shimane University), Chair:Ryosuke Ando(Graduate School of Science, University of Tokyo), Wataru Tanikawa(Japan Agency for Marine-Earth Science and Technology, Kochi Instutute for Core Sample Research)

3:55 PM - 4:20 PM

[SSS27-07] Periodic slow slip and megathrust zone earthquakes in northeastern Japan

★Invited papers

*Naoki Uchida1, Takeshi Iinuma2, Robert Nadeau3, Roland Bürgmann3, Ryota Hino1 (1.Graduate School of Science, Tohoku University, 2.Japan Agency for Marine-Earth Science and Technology, 3.University of California, Berkeley)

Keywords:slow slip, repeating earthquakes, interplate earthquakes

Both aseismic and seismic slip accommodate relative motion across partially coupled plate boundary faults. In northeastern Japan, aseismic slip occurs in the form of decelerating afterslip following large interplate earthquakes and as relatively steady slip on uncoupled areas of the subduction thrust. Here we report on a new quasi-periodic slow-slip behavior that is widespread in the megathrust zone. The repeat intervals of the slow slip range from 1 to 6 years and often coincide with or precede clusters of large (M ≥ 5) earthquakes, including the M9 Tohoku-oki earthquake. The examination of the spatio-temporal distribution of small repeating earthquakes with respect to the M ≥ 5 earthquakes suggests that the slow-slip pulses trigger the M ≥ 5 seismicity. These results suggest that inherently periodic slow-slip events result in periodic stress perturbations and modulate the occurrence time of larger earthquakes. The periodicity in the slow-slip rate has the potential to help refine time-dependent earthquake forecasts.