2017年伊拉克MW7.3地震的类型界定及其震后趋势分析

2017年伊拉克地震发生在我们划分的巴格达地震区，鉴于不同机构提供的该震震级参数相差较大，本文利用孕震断层多锁固段脆性破裂理论，分情况讨论了该震所属地震类型，并分析了巴格达地震区地震趋势.结果表明：若2017年伊拉克地震为M_W7.3，则该震为第3锁固段向峰值强度点演化过程中发生的1次显著前震，该区未来将发生M_W7.7~8.2（双震型为M_W7.5~8.0）标志性地震，目前已接近临界状态；若2017年伊拉克地震为M_W7.5，除可能为显著前震外，还可能为标志性地震（双震）之一，若如此两年内该区将发生另一次M_W7.5地震；若2017年伊拉克地震为M_S7.8，则该震为第3锁固段峰值强度点对应的标志性地震，与我们对该震的前瞻性中长期预测结果相符.我们判断该震不为主震，预测该区未来还将发生M_W7.8~8.3（双震型为M_W7.6~8.1）标志性地震，目前该区远离临界状态.

Identification of seismic type of 2017 Iraq MW7.3 earthquake and analysis of its post-quake trend

The 2017 Iraq M_W7.3 earthquake occurred in the Baghdad seismic zone defined by us. The seismic type of the earthquake is discussed according to its different magnitude parameters provided by various agencies, and then its post-quake trend in this seismic zone is analyzed in this paper, based on the theory about the brittle failures of multiple locked patches in a seismogenic fault system. The present results show that if the 2017 Iraq earthquake is with a magnitude of M_W7.3, it is identified as a significant foreshock occurred in the evolution process towards the peak strength point of the third locked patch, demonstrating that a M_W7.7~8.2 (or double earthquakes of M_W7.5~8.0) characteristic earthquake will take place in the near future because the seismic zone has closed to the critical state; if the 2017 Iraq earthquake is viewed as M_W7.5, it may yet be one of the double-shock-type characteristic earthquakes besides as a significant foreshock,implying that the other M_W7.5 earthquake will strike the seismic zone within two years; if the 2017 Iraq earthquake is viewed as M_S7.8, it is identified as a characteristic earthquake occurred at the peak strength point of the third locked patch, which is in good agreement with our prospective medium-to-long term prediction of this earthquake. Furthermore, we judge that the M_S7.8 earthquake is not a mainshock, demonstrating that the next M_W7.8~8.3 (or double earthquakes of M_W7.6~8.1) characteristic earthquake will take place in the remote future because the seismic zone is far from the critical state at present.