考虑震源机制解的地震丛集区搜索方法

Determining earthquake clustering regions by considering focal mechanisms

构造带区段的划分对地震区划与构造演化等研究有着重要作用,而地震丛集区可以为构造带区段的划分提供参考依据.本文发展了一种考虑震源机制解的地震丛集区搜索方法:基于震源机制解的四元数表示方法来定量评估不同地震的震源机制解的相似程度,并以满足给定相似度阈值条件的地震所占比例作为判据来确定地震丛集区.合成数据的测试结果显示,该方法能够对地震丛集区做有效搜索并区分具有不同震源机制特征的丛集区.将该方法应用于2011年日本M 9.0东北大地震显示,搜索得到的地震丛集区与实际观测到的余震特征分布具有较好的一致性,表明该方法可以为实际的地震丛集区划分提供一条有效的途径.

Zonation of tectonic belts plays an important role in the analyses of seismic zoning and tectonic evolution.Determination of earthquake clustering regions provides a basis for tectonic belt zonation.In this paper,we develop a new method to search for earthquake clustering regions by taking the focal mechanisms of earthquakes into consideration.We use the quaternion representation of focal mechanisms to quantify their similarity,and determine the earthquake clustering region based on the proportion of the events satisfying a given similarity threshold among all events in the region.Synthetic tests indicate that the method can effectively search for earthquake clustering regions and distinguish regions with dissimilar focal mechanisms.Application to the 2011 Tohoku earthquake yields clustering regions in good agreement with the observed characteristic distribution of aftershocks,demonstrating that the new method provides an effective means for the determination of earthquake clustering regions.