Japan Geoscience Union Meeting 2018

Presentation information

[EE] Poster

S (Solid Earth Sciences) » S-CG Complex & General

[S-CG53] Science of slow earthquakes: Toward unified understandings of whole earthquake process

Wed. May 23, 2018 3:30 PM - 5:00 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Satoshi Ide(Department of Earth an Planetary Science, University of Tokyo), Hitoshi Hirose(Research Center for Urban Safety and Security, Kobe University), Kohtaro Ujiie(筑波大学生命環境系, 共同), Takahiro Hatano(Earthquake Research Institute, University of Tokyo)

[SCG53-P24] Quantitative relationship between slow slip propagation speed and frictional properties

*Keisuke Ariyoshi1, Roland Burgmann2, Jean-Paul Ampuero3, Toru Matsuzawa4, Akira Hasegawa4, Ryota Hino4, Takane Hori1 (1.Japan Agency for Marine-Earth Science and Technology, 2.University of California, Berkeley, 3.California Institute of Technology, 4.Tohoku University)

Keywords:afterslip, effective normal stress, stress perturbation, rate- and state-dependent friction law

Motivated by recent observations of the migration of slow slip, such as postseismic slip and slow earthquakes, the propagation of tremor and very low-frequency earthquakes, and the expansion of aftershock areas, we develop a new analytical relationship between the migration speed of aseismic slip transients and frictional properties of the fault, modeled by a rate- and state-dependent friction law. The relationship explains the migration speed of slow slip in 3-D numerical model simulations to first order, except near the earth’s surface. Based on this relationship, we suggest that lower values of the frictional parameter a-b (which quantifies the velocity-dependence of steady-state friction) and of the effective normal stress σ cause faster propagation for small amount of shear stress loading due to the passage of postseismic slip, while reducing the frictional parameter a (which quantifies the instantaneous velocity-dependence of friction) is more effective at accelerating slow-slip propagation for large amount of shear stress loading. The characteristic slip distance dc is inversely proportional to the migration speed. This relationship should be useful to constrain the frictional properties of faults based on observed migration speeds, independent of rock laboratory experiments, which can then be used in predictive numerical simulations of slow slip phenomena.