title: Periodic slow slip triggers megathrust zone earthquakes in northeastern Japan.
abstract: 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 after large interplate earthquakes and as relatively steady slip on uncoupled areas of the subduction thrust. Here we report on a previously unrecognized 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 [magnitude (M) ≥ 5] earthquakes, including the 2011 M 9 Tohoku-oki earthquake. 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.
authors.affiliation: Graduate School of Science and International Research Institute of Disaster Science, Tohoku University, 6-6, Aramaki-aza-aoba, Aoba-ku, Sendai 980-8578, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Uchida
authors.affiliation: International Research Institute of Disaster Science, Tohoku University, 468-1, Aramaki-aza-aoba, Aoba-ku, Sendai 980-0845, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Iinuma
authors.affiliation: Berkeley Seismological Laboratory and Berkeley Institute for Data Science, University of California, Berkeley, 211 McCone Hall, Berkeley, CA 94720-4767, USA.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Nadeau
authors.affiliation: Berkeley Seismological Laboratory and Department of Earth and Planetary Science, University of California, Berkeley, 389 McCone Hall, Berkeley, CA 94720-4767, USA.
authors.forename: Roland
authors.initials: R
authors.lastname: Bürgmann
authors.affiliation: Graduate School of Science and International Research Institute of Disaster Science, Tohoku University, 6-6, Aramaki-aza-aoba, Aoba-ku, Sendai 980-8578, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Hino