区域优势构造面和余震节面库仑应力变化相关性与地震预测意义  

Correlation between the Coulomb stress change on regional dominant faults and that on aftershock nodal planes,and its implication for earthquake prediction

作　　者：陈兵[1] 崔笃信[1] 张晓亮[1] 王庆良[1] 

机构地区：[1]中国地震局第二监测中心,中国西安710054

出　　处：《地震学报》2009年第4期357-366,共10页Acta Seismologica Sinica

基　　金：中国自然科学基金项目(40674057)资助

摘　　要：根据2001年昆仑山口西8.1级地震震源机制,计算了主震破裂在区域优势直立走滑构造面上引起的库仑应力变化,发现3级以上余震大部分分布在库仑应力变化为正的区段,与应力的正相关性为56%—71%;5级余震与应力的正相关性达到60%—80%.5级余震节面上库仑应力变化的正相关性为60%—80%,其效果与优势构造面具有等价性.表明应用库仑应力函数方法分析区域优势构造面应力变化,可能是判断未来地震活动发生地点的一条有效途径.其物理机制可能源于地壳应变主体单元中区域应变能与单元中包含的不同尺度断层面上应力分布的正相关性.亦即主破裂造成沿区域优势构造产生应力的不均匀分布,应力的非均匀性引起区域应变能的非均匀分布,在应变能升高的区段,某些次生断裂面应力随之升高,从而引发余震活动.Based on the focal mechanism solution of the 2001 Ms8.1 earthquake west to Kunlun Mountain Pass, the Coulomb stress change on regional dominant faults induced by the main-shock were calculated. We noticed that most aftershocks （ML ≥ 3. 0） occurred in the region with positive Coulomb stress change, with the coincidence between them reaching to 56%-71%. For ML≥ 5.0 aftershocks, 60%-80% of their possible fault planes show positive Coulomb stress change. This coincidence rate of 60%-80% for ML ≥ 5. 0 after- shocks is close to the consistence rate for regional dominant faults. This suggests that analyzing Coulomb stress change on regional dominant faults may be a useful way for predicting future earthquake positions. Its mechanism may be that there is positive correlation between the stress on the faults of difference scales and the regional strain energy in main elements of the crust. Namely, the mainshock produces heterogeneous stress distribution along the regional dominant faults, and on some branch faults with increased strain energy occurred the aftershoeks.

关 键 词：库仑应力变化 区域优势构造 余震 地震预测 

分 类 号：P315.3[天文地球—地震学]