2013年吉林省松原地区MS≥5地震群成因研究

Study on Genesis of MS≥5 Songyuan Earthquake Swarm in Jilin Province in 2013

2013-10-31~11-23吉林省松原地区连续发生5次M S≥5.0地震,其中最大地震为2013-11-23 M S5.8地震,该震群的突发性及密集性与区域历史构造地震特征不相符。通过计算2013年松原地区5次M S≥5地震零频极限值的相关系数发现,第1次和第5次地震的震源机制相似性较大,第2次、第3次和第4次地震的震源机制相似性较大。将松原地震同典型的构造地震和塌陷地震的地震参数进行比较发现,2013年松原地震的位移震源谱较典型构造地震呈现衰减早、衰减快的特征,波形复杂度和谱比值等时域、频域特征参数也与典型构造地震相差较大,更符合塌陷型地震的特征。

A series of earthquakes occurred in Songyuan area,Jilin province between October 31 and November 23,2013,including five M S≥5 earthquakes.The largest one,of M S5.8,occurred November 23,2013.By calculating the correlation coefficients of the spectral amplitude of these five M S≥5 earthquakes in Songyuan area in 2013,it is found that the focal mechanisms of the first and fifth earthquakes are similar,while those of the second,third and fourth earthquakes are similar.Statistical analysis on these five earthquakes and compared with tectonic earthquakes and collapsed earthquakesshows that the displacement source spectrum of Songyuan swarm in 2013 presents the characteristics of early attenuation and fast attenuation compared with tectonic earthquakes.Characteristic parameters of time-domain and frequency-domain,such as waveform complexity and spectral ratio,are also quite different from those of tectonic earthquakes,but more in line with the characteristics of collapsed earthquakes.