地球自转减速对2008年汶川M_S8.0地震的作用

Effect of the Earth Rotation Deceleration on the Occurrence of the 2008 Wenchuan M_S8.0 Earthquake

本文将地球看成是一个质量分布均匀的球对称弹性球体,给出了地球以匀角速率旋转情况下产生的应力场的解析表达式,计算了地球匀速自转时在2008年汶川MS8.0地震发震断层面上产生的应力,分析了地球自转速率变化对汶川地震发震断层的影响。结果表明,地球自转减速有利于汶川地震发生。如果地球自转减速对汶川地震的发生起到了触发作用,那么在震前震区或许会出现中小地震发生受到地球自转减速触发的现象。分析表明,从2006年起汶川地震震中附近地区ML≥2.7地震受到地球自转减速的触发,这从另一个侧面说明了地球自转减速对汶川地震的发生具有促进作用。

Stress changes produced by the earth are obtained with a spherically symmetrical and elastic sphere of uniformly-distributed mass and rotating in constant angular rate.The stress changes caused by the earth rotating in constant angular rate on the focal fault plane of the 2008 Wenchuan MS8.0 earthquake are calculated.The effect of changes of the earth＇s rotation rate on the focal fault plane of the Wenchuan earthquake is discussed.The result shows that deceleration of the earth rotation could promote the initiation of the Wenchuan earthquake.On the other hand,if the deceleration of the earth rotation played a positive role in the Wenchuan earthquake occurrence,there could exist some small deceleration of the earth rotation-triggering earthquakes around the epicenter area of the Wenchuan earthquake.Our analysis shows that earthquakes of ML2.7 around the epicenter area of the Wenchuan earthquake could be triggered by the deceleration of the earth rotation.It provides another evidence for the positive role of the deceleration of the earth rotation in the initiation of the Wenchuan earthquake.