Characteristics of Far-field Seismic Radiated Energy from the Five Earthquakes with MS≥5. 0 in the Earthquake Swarm Sequence of 2013,MS5. 8,Qianguo,Jilin Province,China

摘要

The Qianguo M_S5. 8 earthquake swarm of 2013 occurred in Qianguo,Jilin Province,China. There are five earthquakes with M_S≥5. 0 in the Qianguo earthquake swarm,with magnitudes of M_S5. 5,M_S5. 0,M_S5. 3,M_S5. 8 and M_S5. 0. In this study,the far-field seismic radiated energy characteristics of the earthquakes are compared based on the source spectrum and the ground motion spectrum of the earthquake swarm. The ground motion spectrum of the five earthquakes at Changchun seismic station( CN2),which is the national standard station,is first investigated with the recorded ground motions,and then the far-field seismic radiated energy is calculated and combined with the relationships of the source spectrum to describe the variable characteristics of the Qianguo earthquake swarm. Research results indicate that the second earthquake( No. 2) with M_S5. 0 is the key event of the earthquake swarm,which occurred on October 31,the same day following the first M_S5. 5 earthquake( No.1). In fact,the magnitude of event No. 2 decreased compared to event No.1,which did not agree with its large far-field seismic radiated energy. It needs to be pointed out that event No. 2 was the turning point event of the Qianguo earthquake swarm,as being a significant transition before the largest M_S5. 8 earthquake.