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Effects of changes in temperature and fluid pressure on dynamic earthquake rupture in a thermo-poroelastic medium

Research Project

Project/Area Number 15540401
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Solid earth and planetary physics
Research InstitutionThe University of Tokyo

Principal Investigator

YAMASHITA Teruo  The University of Tokyo, Earthquake Research Institute, Professor, 地震研究所, 教授 (10114696)

Project Period (FY) 2003 – 2004
Project Status Completed (Fiscal Year 2004)
Budget Amount *help
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 2004: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2003: ¥900,000 (Direct Cost: ¥900,000)
Keywordspooelastic nedia / earthquake / fault / slip weakening / 熱多孔性媒質 / 地下流体 / 流体 / 熱 / 断層帯
Research Abstract

We theoretically study thermo-hydraulic effects on dynamic earthquake rupture. First, the system of governing equations is derived assuming a thereto-poroelastic medium, and then numerical calculations are carried out based on these equations. Non-linear feedbacks among changes in temperature, fluid pressure and fault slip are shown to play important roles in the rupture dynamics. For example, the duration of fault slip is found to be longer than expected from the classical Griffith crack model located in an elastic medium because of these feedbacks ; the deviation from the solution for the Griffith crack model is larger when the thickness of heated fault zone is larger. The feedbacks also produce slip-weakening behavior and gradual slip onset. Slip-weakening distance is shown to be larger when the rate of fluid outflow from the heated fault zone is larger. A tendency is also found in our simulations that smaller-size events have smaller stress drops, which is consistent with some seismological observations ; the difference in the stress drop between small-and large-size events is larger when the permeability of the medium is smaller. This occurs because ongoing fault slip tends to raise fluid pressure. Our simulations in this paper suggest that scaling relation between small-and large-size earthquakes are rather complicated because of thermo-hydraulic effects.

Report

(3 results)
  • 2004 Annual Research Report   Final Research Report Summary
  • 2003 Annual Research Report

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Published: 2003-04-01   Modified: 2016-04-21  

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