2010年智利Bio-Bío M_(W)8.8地震前震中附近地区断层面上的摩擦系数变化特征

The variation features of friction coefficient on the fault planes around the epicenter preceding the 2010 Bio-Bío,Chile M_(W)8.8 earthquake

利用1990年1月1日—2010年2月26日期间发生在2010年智利Bio-Bío M_(W)8.8地震震中附近地区的100次5.0≤M_(W)≤6.9地震震源机制解结果,计算了断层面上的摩擦系数,并得到了摩擦系数随时间的变化。结果表明,震前从2006年初开始直至临近主震发生的约4年零2个月时间内,震中附近地区发震断层面上的摩擦系数随时间呈趋势下降变化;从2006年初的约0.73下降到临震前的约0.4,相对下降幅度达45.2%。这个结果对认识强震孕育过程以及地震预测研究均具有启示意义。

For one hundred earthquakes(5.0≤M_(W)≤6.9)that occurred around the epicenter of the 2010 Bio-Bío,Chile M_(W)8.8 earthquake from 1 January 1990 to 26 February 2010,their focal mechanism solutions were used to calculate the friction coefficient on the fault plane and the friction coefficient as a function of time.The results show that within the period of four years and two months from the beginning of 2006 until the occurrence of the Bio-Bío mainshock the friction coefficient around the epicentral area showed a decreasing trend,dropped from about 0.73 at the beginning of 2006 to about 0.4 immediately towards the occurrence of the Bio-Bío mainshock,with a relative decrease of 45.2%.It will be of great significance for understanding the occurrence process of strong earthquakes and earthquake prediction.