摘要
为了把握断层上地震的前兆规律 ,对连续介质中断层面上的地震成核过程进行了数值模拟研究。摩擦采用了速率及状态依赖性本构关系 ,并考虑了正应力变化的影响。结果表明 ,在成核的后期阶段 :①最大位移速率单调加速增加 ;②滑动热点 (最大滑动速率处 )在后期阶段开始自发性迁移 ,且在空间上连续 ;③当最大滑动速率达到可以明显探测的量级时 (高于加载速率一个数量级以上 ) ,倒计时间为 2 0小时或更长一些 ,这时的速率变化可作为临震预测标志 ;④平均滑动速率与倒计时间的关系在临震阶段呈对数线性趋势 ,由此可推测微震活动增长率与倒计时间同样存在对数线性关系 ;⑤正应力的变化对上述时间尺度有延长作用 ,使之大致增加到原数值的 2倍。
To unerstand precursory process before seismic fault slip, this work focuses on earthquake nucleation process on a fault plane through numerical simulation.Rate and state dependent friction law with variable normal stress is employed in the analyses. The results show that in the later stage of the nucleation process,① The maximum slip velocity is monotonically accelerating;② The slipping hot spot (where the slip rate is maximum) migrates spontaneously from a certain instant, and such migration is spatially continuous;③When the maximum velocity reaches a detectable order of magnitude (at least one order of magnitude greater than the loading rate), the remaining time is 20 hours or more, and the temporal variation of slip velocity beyond this point may be used as a precursory indicator;④ The average slip velocity is related to the remaining time by a log\|log linear relation, which means that a similar relation between rate of microseismicity and remaining time may also exist;⑤ When normal stress variation is taken into account, time scale of such processes can be extended by about 2 times.
出处
《中国地震》
CSCD
北大核心
2000年第1期1-13,共13页
Earthquake Research in China
基金
"国家重点基础研究专项经费"!(编号G19980 40 70 4)
中国地震局"九五"重点课题!(95 0 4 0 3 0 2 0 2 )
关键词
断层
地震成核
摩擦
数值模拟
地震前兆
Fault\ Earthquake nucleation\ Friction\ Numerical simulation
