玛尼7.9级地震对昆仑山口西8.1级地震的触发作用及动力背景初探

Study of Triggering Action Between Mani(M_S7.9) and Kunlun(M_S8.1) Great Earthquakes and Their Dynamic Background

根据库仑静应力变化的概念 ,对青藏块体中部地区 1997年 11月 8日玛尼 7 9级地震及 2 0 0 1年 11月 14日昆仑山口西 8 1级地震的应力触发作用进行了初步研究。不同震源机制解计算结果表明 ,玛尼地震造成了昆仑地震断层面上 10 -3 MPa量级的库仑应力增量 ,该变化仅使得昆仑地震的发生提前了最长 10年左右 ,表明当前地壳应变能水平可能并不很低。对照2 0世纪初以来全球 7级以上强震频度和强度演化特征与地球自转变化的关系 ,认为地球自转幅度衰减、变化频率升高是近期强震活动的重要控制因素。昆仑山口西 8 1级地震的发生 ,可能是地球自转持续加速阶段后期 ,青藏块体内部区域应力场逐渐强化 ,及玛尼地震应力触发的结果。

Based on Coulomb static stress variation, the stress trigging action of Mani( M S7.9, Nov. 1997) earthquake to Kunlun( M S8.1, Nov. 2001)earthquake has been studied. Results of different epicenter mechanism solution show that, 10 -3 MPa Coulomb stress due to Mani earthquake is added to the fracture fault of Kunlun earthquake, and this may shift the broken date to earlier about 10 years, and infer that the stress level in crustal is not low. Comparing of relation between strong earthquakes' strength and frequency and earth rotation change shows that, the strength's decreasing and changing period's shortening of earth rotation are the important controlling factor on strong earthquakes' activity. This great event took place properly due to accumulating strengthening background of regional stress field of inter-Qinghai-Xizang block in the period of acceleration of change of day's length and stress triggering of Mani earthquake.