Time-spacio change in effective friction coefficient with seismic cycle in subduction zones

2014 Fiscal Year Final Research Report

• Project/Area Number: 24340125
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Geology
• Research Institution: Kochi University
• Principal Investigator: HASHIMOTO Yoshitaka 高知大学, 自然科学系, 准教授 (40346698)
• Co-Investigator(Kenkyū-buntansha): UJIIE Kohtaro 筑波大学, 生命環境科学研究科(系), 准教授 (40359188) ; YAMAMOTO Yuzuru 独立行政法人海洋研究開発機構, 地球内部ダイナミクス領域, 研究員 (10435753)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 沈み込みプレート境界地震 / 付加体 / 古応力 / 有効摩擦係数

Outline of Final Research Achievements

The purpose of this study is to examine a time-spacio change in paleo-stress and effective friction coefficient with seismic cycle. We conducted paleo-stress estimation, elastic wave velocity measurements and estimation of fluid temperature and pressure.
In the results, we obtained the horizontal compressional principal stress in the direction of plate convergence as expected. And the horizontal extensional principal stress was also detected generally. Effective friction coefficient is larger in former and smaller in latter, which corresponds larger fluid pressure in former than that in latter. The changes in paleo-stress and others can be explained by the stress switch associated with stress drop at the time of seismogenesis. Elastic properties at boundary faults and temperature and pressure of fluid indicate the high fluid pressure along the fault, which is coincident with the state before or at the time of seismogenesis.

Free Research Field

地質学