基于库仑应力变化研究台湾强震对福建地区地震触发作用

Effect of Earthquake Triggering in Fujian by the Taiwan Strong Earthquakes Based on Coulomb Stress Changes

考虑同震位错与震后黏弹性弛豫效应,采用分层地壳介质模型,定量计算了台湾地区M_S≥7.0强震对福建地区部分M_L≥4.0地震的库仑应力影响。结果显示:台湾强震对福建M_L≥4.0地震的发生影响较小,远没有达到地震触发阈值,不具有触发作用,其主要原因是这两地区距离较远。结合台湾与福建地区M-T图,认为虽然台湾强震与福建地震不属触发关系,但可以用"同期活跃"的特征来描述。当大区域背景应力状态处于较高水平时,台湾地区M_S≥7.0强震与福建地区M_L≥4.0地震同时较为活跃。在此情况下,台湾M_S≥7.0强震与福建地区M_L≥4.0地震哪个先发生都是可能的。

Considering the coseismic dislocation and postseismic viscoelastic relaxation effect, the paper quantitatively calculated Coulomb stress effect of MS≥7.0 strong earthquakes in Taiwan regions on some ML≥4.0 earthquakes in Fujian region by using the layer crust model. This result shows that strong earthquakes in Taiwan regions had a very small effect on ML≥4.0 earthquakes in Fujian region. This effect did not reach the triggering threshold in large degree and had no triggering effect. The main reason is that the distance between the strong earthquakes with MS≥7.0 in Taiwan regions and earthquakes with ML≥4.0 in Fujian region is too far. Although relation between the Taiwan strong earthquakes and Fujian earthquakes can not be depicted by triggering effect, it can be seen as ＂synchronous active period＂ through the M-T of the area of the Taiwan and Fujian region. When the level of the background stress state in the large scale area is high, MS≥7.0 strong earthquakesin Taiwan regions and ML≥4.0 earthquakes in Fujian region would be active synchronously. Under the circumstances, either of MS≥7.0 earthquakes in Taiwan regions or ML≥4.0 earthquakes in Fujian region could first occur.