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

温度和流体压力变化对热多孔弹性介质中动态地震破裂的影响

基本信息

批准号：
15540401
负责人：
YAMASHITA Teruo
金额：
$ 1.15万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15540401/
关键词：
pooelastic nedia earthquake fault slip weakening 熱多孔性媒質地下流体流体熱断層帯

项目摘要

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.

从理论上讲，我们研究热液压对动态地震破裂的影响。首先，假设使用poro弹性介质，则得出了管理方程式系统，然后根据这些方程进行数值计算。温度变化，流体压力和断层滑动的变化之间的非线性反馈在破裂动力学中起着重要作用。例如，由于这些反馈，因此发现断层滑移的持续时间比位于弹性介质中的经典griffith裂纹模型的预期更长。当加热断层区域的厚度较大时，与格里菲斯裂纹模型的溶液偏差更大。这些反馈还会产生滑动的行为和逐渐滑动的发作。当从加热断层区域的流体流出速率较大时，滑动距离较大。在我们的模拟中也发现了一种趋势，即较小的事件的应力下降较小，这与某些地震学观察一致。当培养基的渗透性较小时，小事件之间应力下降的差异更大。之所以发生这种情况，是因为持续的断层滑动倾向于增加流体压力。我们在本文中的模拟表明，由于热液压效应，大小地震之间的缩放关系相当复杂。