loading page

Frictional and Hydraulic Properties of Plate Interfaces Constrained by a Tidal Response Model Considering Dilatancy/Compaction
  • Ryunosuke Sakamoto,
  • Yoshiyuki Tanaka
Ryunosuke Sakamoto
Osaka University, Osaka University

Corresponding Author:sakamoto@neq.ess.sci.osaka-u.ac.jp

Author Profile
Yoshiyuki Tanaka
University of Tokyo, University of Tokyo
Author Profile


Tidal triggering of tectonic tremors has been observed at plate boundaries around the circum-Pacific region. It has been reported that the response of tremors to tidal stress during episodic tremor and slow slip (ETS) changes between the early and late stages of ETS. Several physical models have been constructed, with which observations for the tidal response during ETS have been partly reproduced. However, no model has been proposed that reproduces all the observations. In this study, a model adopted in previous studies is extended to include the effects of dilatancy/compaction that occur in the fault creep region. The analytical approximate solution derived in this study and numerical computational results reveal how the tidal response depends on physical properties of the fault. Furthermore, the model reproduces all the above observations simultaneously for a specific range of fault parameters. Of particular importance is that the occurrence of dilatancy/compaction is essential to reproduce the tidal response at the early stage of ETS. The value of the critical distance dc is constrained to be approximately 10 cm. This is in agreement with the values that have been widely used in seismic cycle numerical simulations rather than those obtained in laboratory experiments. The fluid pressure diffusivity is constrained to be at least 10^(-5) m^(2)/s or less, and the effective normal stress is constrained to 10^(5~6) Pa. In conclusion, this study shows that reproducing the tidal response of tectonic tremors during ETS is useful for estimating fault physical properties, including hydraulic properties.