Scaling relation in slip deficit during the interseismic period from numerical simulations

Hideo Aochi (1) , Satoshi Ide (2)

1 BRGM - Bureau de Recherches Géologiques et Minières
2 Department of Earth and Planetary Science [Tokyo]

Scaling relation of “standard” earthquakes can be explained by the hierachical property and structure in fracture energy during the coseismic weakening process from the mechanical point of view (e.g. Aochi and Ide, GRL, 2004; Ide and Aochi, JGR, 2005). Namely it is important that the slip weakening distance in friction law is proportional to the heterogeneity (patch) size. Now we are interested in the scaling of “slow” earthquakes and aseismic slip along a fault during steady loading. According to the analogy from our previous studies, we consider patches of different sizes, attributed particular frictional parameters. For the simplicity, we suppose a simple equation,(w) = (w/wc) exp(1-(w/wc)), where shear friction  is a function of cumulative slip w and with a factor  (>0), a constant  and characteristic length wc. We then consider a constant loading rate V surrounding the model area. Stress accumulation on patches prior to the weakening process depends on the patch size, and slip deficit is cumulated the most when stress is at peak. The time to the maximum slip deficit and the slip deficit amount are briefly proportional to the patch size, regardless if wc is scale-dependent or not. The numerical simulations suggest that slip deficit rate is size-invariant under the same loading if wc is proportional to the patch size and  = 1. Furthermore if wc is scale-dependent and  = 2, the slip deficit rate is reversely related to the patch size. Namely, slip deficit rate is smaller for a large slow slip event. Scaling relation in hardening process (interseismic process) has been hardly taken into account, but this should be a key to understand the scaling relation during the interseismic period for slow slip events and repeating earthquakes.

Domaines: Géophysique [physics.geo-ph]

Hideo Aochi, Satoshi Ide. Scaling relation in slip deficit during the interseismic period from numerical simulations. Seismological Society of America Annual Meeting 2015, Apr 2015, Pasadena, United States. ⟨hal-01101249⟩