山东及其近海小震群活动特征研究

Study on the Characteristics of the Small Seismic Swarms Occurring in Shandong Province and Its Nearby Ocean Floor

对山东及其近海30多年来发生的39次小震群资料进行了系统的整理、分析。结果表明:这39次小震群大多分布在断裂带上,发生在2条(或2条以上)断裂交汇部位的占67%,这些容易发生小震群的断层大多为走滑性质的活动断裂,占到86.5%;其中主余型的占57%,双震型的占32%,多震型的占11%,该区震群活动与外围的中、强地震对应率为56%,其中的较显著小震群与外围的中、强地震对应率为71%。对震群与中强地震的间隔时间和间隔距离,以及与区域地震构造的关系进行了初步分析。

In this paper,39 small seismic swarms occurring in Shandong Province and its nearby ocean floor during the past more than 30 years were classified and analyzed systematically.The results show that the 39 small seismic swarms mostly distributed on seismic faults,67% of which took place on the jointing parts of 2 or more faults.86.5% of the faults,where small seismic swarms are easily be triggered,are active strike slip faults.57% of the small seismic swarms are of the mainshock-aftershock type,32% of them are of the double-shock type,and 11% of them,the multiple-shock type.56% of the cases in which a small seismic swarm event in the above region correspond to an earthquake of moderate,or strong,intensity in the periphery region.Among the remarkable small seismic swarms,the corresponding rate is 71%.Parameters of the remarkable seismic swarms are analyzed in this paper.