Preliminary analysis of the 2017 Jinghe M_S6.6 earthquake sequence and its seismic source characteristics
Jiang Xianghua;Han Yanyan;Yang Wen;Meng Lingyuan;China Earthquake Networks Center;
On August 9,2017,the earthquake with M_S6.6 occurred in Jinghe County,Xinjiang,China,with epicenter at 44.3°N,82.9°E. Its focal depth was 11 km. The Jinghe M_S6.6 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 5 km to 15 km. In order to study the feature of the earthquake sequence,we graph their magnitudes against time up to August 20,2017. The earthquakes with M_L2.0 and M_L3.0 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 M_S5.6. The h-value from Omori's law is 2.17. The relation between the ‘wait time' of an aftershock with magnitude over M_S4.0 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 10 km 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.
【Fund】： 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
【CateGory Index】： P315
【CateGory Index】： P315