2008年、2009年大柴旦两次6级地震序列地震视应力特征

Apparent stress features of two strong earthquake sequences in Qinghai Da Qaidam

计算得到2008年、2009年大柴旦两次6级地震序列中109个ML≥3.0地震的视应力,两次序列主震视应力分别为5.1 MPa、3.4 MPa,平均视应力为0.48 MPa。2008年地震序列视应力的整体平均水平小于2009年地震序列,综合USGS及哈佛大学CMT给出的震源参数,发现两次地震震中相近,但震源深度有很大差异,2008年地震深度约25 km,而2009年地震震源深度约12 km,震源深度及发震构造的差异可能造成两次地震序列视应力的不同。

The apparent stress of 109 ML≥ 3.0 in two MS 6 earthquake sequences occurred in 2008 and 2009 in Da Qaidam calculation were calculated, the two main earthquake apparent stresses are 5.1 MPa and 3.4 MPa respectively, the average apparent stress is 0.48 MPa. However, the apparent stress of 2008 sequence is less than the 2009 sequence in general. According to the focal parameters given by USGS and CMT, it is easily found that the two epicenters were quite near, but the differences of in the focal depths are great, the depths of 2008 earthquake is about 25 km, and the latter is just about 12 km. Difference of the focal depth and causative structure may cause the apparent stress difference of the two earthquake seismic sequences.