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2017年精河MS6.6地震序列及震源特征初步分析
姜祥华,韩颜颜,杨文,孟令媛
作者单位E-mail
姜祥华 中国地震台网中心, 北京市西城区三里河南横街5号 100045  
韩颜颜 中国地震台网中心, 北京市西城区三里河南横街5号 100045 hanyy@seis.ac.cn 
杨文 中国地震台网中心, 北京市西城区三里河南横街5号 100045  
孟令媛 中国地震台网中心, 北京市西城区三里河南横街5号 100045  
摘要:
2017年8月9日新疆博尔塔拉州精河县发生MS6.6地震,震中44.3°N、82.9°E,震源深度11km,精河地震发生在库松木契克山前断裂附近,基于远震波形记录反演的震源机制为逆冲型,地质调查结果显示主震破裂未出露地表。利用地震精定位研究余震的空间分布,结果显示,余震展布与库松木契克山前断裂的走向基本吻合,且余震主要分布在主震西侧,单侧破裂特征明显,余震的深度集中在5~15km。基于M-t图分析序列的衰减特征发现,截至2017年8月20日,序列中ML2.0、ML3.0余震相对丰富,衰减基本正常。G-R关系给出的b值为0.54,外推最大余震震级为MS5.6,h值为2.17,均显示该序列为主-余型。MS≥4.0余震的等待时间与发生时间较好地满足双对数线性关系,同样为主-余型地震的特征。断层面上静态滑动量分布相对单一且集中,最大滑动位于沿倾向10km处附近,与地质调查主震断层未出露地表的结果一致,同时也表明主震破裂较充分。基于数字波形资料计算出的余震视应力与震级间很好地符合指数关系,扣除震级变化影响后的序列视应力未出现显著高值,也表明此次破裂的能量释放比较充分。
关键词:  精河MS6.6地震  精定位  地震序列  震源参数
DOI:
分类号:P315
基金项目:川滇国家地震监测预报实验场项目(2016CESE0101)、国家自然科学基金(41504047、41404045)共同资助
Preliminary analysis of the 2017 Jinghe MS6.6 earthquake sequence and its seismic source characteristics
Jiang Xianghua,Han Yanyan,Yang Wen,Meng Lingyuan
Abstract:
On August 9, 2017, the earthquake with MS6.6 occurred in Jinghe County, Xinjiang, China, with epicenter at 44.3°N, 82.9°E. Its focal depth was 11km. The Jinghe MS6.6 earthquake occurred near Kusongmuqike piedmont fault. Its focal mechanism inversed from teleseismic waveforms is reverse faulting. Geological investigation shows that the rupture in the earthquake didn't reach to the earth surface. According to the results of high-resolution event relocation, the aftershocks distribute nearly along the strike of the Kusongmuqike piedmont fault. As most of the aftershocks locate in the west of the mainshock, the rupture is likely to propagate in single direction. The focal depths of the aftershocks concentrate between 5km to 15km. In order to study the feature of the earthquake sequence, we graph their magnitudes against time up to August 20, 2017. The earthquakes with ML2.0 and ML3.0 are abundant and the sequence attenuates near regularly. The b-value from the G-R law is 0.54, and the extrapolated maximum aftershock magnitude is MS5.6. The h-value from Omori's law is 2.17. The relation between the ‘wait time’ of an aftershock with magnitude over MS4.0 and its ‘occurrence time’ is studied. We find the logarithmic of the ‘wait time’ is linear with the logarithmic of the ‘occurrence time’. So the Jinghe earthquake sequence should be a mainshock-aftershock type. Inversion from the teleseismic data shows that slips distribute simply on the fault. The maximum slip concentrates on 10km along the dip. This result is consistent with the geological investigation which proposed the rupture didn't extend to the earth surface. The fault slips also indicate that the rupture in the mainshock is sufficient. Apparent stress of aftershocks calculated from digital waveforms increases exponentially with magnitude. Relative apparent stress which removed the change with magnitude doesn't have significantly high value. That also indicates energy was released sufficiently in the rupture process.
Key words:  Jinghe MS6.6 earthquake  High-resolution earthquake location  Earthquake sequence  Seismic source parameter