[关键词]
[摘要]
对震群活动特征的深入研究可以为区域地震危险性分析和地震活动趋势判断提供有效的依据,但受台网布局和震群位置的影响,地震目录中往往会遗漏一些地震,而地震目录的完整性将会影响震群活动特征分析的可靠性。因此,本文利用基于GPU加速的模板匹配方法对山东乳山震群2014年5月至2015年6月期间固定台站和流动台阵记录的连续波形进行扫描,检测出7500个地震事件,为台网目录的4倍,使完备震级从1.0级降至0.2级。基于完备地震目录,利用传染型余震序列(ETAS)模型分析了乳山震群的活动特征。ETAS模型中的随机成分可以作为外力作用触发地震的指标。研究结果表明,乳山震群外力触发的地震所占比例较大,结合前人研究结果,初步推测流体作用可能是外力因素之一,其在乳山震群的发展过程中起一定的作用,但不同时期外力作用对微震活动的触发强度不同。
[Key word]
[Abstract]
The study of swarm activity characteristics can provide effective basis for regional seismic risk analysis and seismic activity trend judgment. However,due to the influence of network layout and swarm location,some earthquakes are often missed,and the integrity of earthquake catalogue will affect the reliability of swarm activity characteristics analysis. Earthquake swarms have occurred frequently in North China since 2013,especially in Rushan,Shandong Province. More than 13000 small earthquakes were recorded in Rushan area on October 1,2013,and the maximum was ML5.0 on May 22,2015. During this period,the seismicity increased and decreased for many times. In this paper,the GPU accelerated template matching method was used to scan the continuous waveforms recorded by the fixed stations and mobile arrays during the period from May 2014 to June 2015 of the Rushan earthquake swarm in Shandong Province. A number of 7500 earthquake events were detected,which was 4 times of the catalogue of the network,and the complete magnitude reduced from 1.0 to 0.2. Based on the completed earthquake catalogue,the activity characteristics of Rushan earthquake group were analyzed by using the model of infectious aftershock series(ETAS). The random components in ETAS model is used as the index of external force triggering earthquake. The Rushan earthquake swarm began to become intensively active in October 2013,while the Rushan array began to operate on May 5,2014. As a result,we added the detection catalogue to the earthquake catalogue of the whole Rushan earthquake swarm,divided the whole development process of the earthquake swarm into five active periods,and analyzed the seismicity of the Rushan earthquake swarm and its variation characteristics in each stage with the help of ETAS model. The results showed that the proportion of the earthquakes triggered by the external force of the Rushan earthquake swarm was large. Combined with the previous research results,it was preliminarily speculated that the fluid effect may be one of the factors of the external force and play a certain role in the development process of the Rushan earthquake swarm,but the triggering intensity of the external force on the microseismic activity was different in different periods.
[中图分类号]
P315
[基金项目]
山东省自然科学基金(ZR2017QD014)资助