以青海、新疆、西藏地区为研究区域,系统研究总结了该区域2010—2020年5.0级以上地震前W_q值的时空演化特征,并以2020年新疆于田6.4级和西藏尼玛6.6级地震为实例进行阐述。得出以下三点认识:①地震一般发生在W_q值异常扩展时段或扩展—减小时段,6.0级以上W_q值异常的震例中,约81%发生于异常出现后的9个月内;②地震一般位于W_q值异常面积扩展区或扩展—减小恢复区附近,近70%的震例发生在W_q值异常区内;③建立了震级与W_q值异常区面积间的正相关统计模型,二者的相关系数(R)为0.85,为预测青海、新疆和西藏地区地震的强度提供了定量关系。青海、新疆和西藏地区W_q值方法对6.0～6.9级地震的预测效果(W_q值异常的地震报准率为61%)优于5.0～5.9级地震(W_q值异常的地震报准率为26%),为我国地球物理观测程度较低地区开展强震中短期(1年内)预测提供了参考依据。

In this paper,the temporal and spatial evolution characteristics of W_q values before earthquakes above M_S5.0 in Qinghai,Xinjiang and Tibet since 2010 to 2020 were systematically summarized. The Xinjiang Yutian M_S6.4 earthquake on June 26,2020 and the Tibet Nima M_S6.6 earthquake on July 23,2020 are taken as examples. The research results suggest that:① Strong earthquakes generally occurred during the W_q values expansion or expansion-decrement periods and about 81% occurred within 9 months after the appearance of the W_q anomaly. ② The epicenters of the earthquakes were generally near the W_q values anomaly expansion areas or the areas of expansion-decrement recovery and nearly 70% of the earthquakes occurred in the area of W_q value anomaly. ③ With a correlation coefficient(R)of 0.85,the statistical relationship between the magnitude and the areas of abnormal W_q was established,which provided a quantitative model for the prediction of medium-short term earthquakes in Qinghai,Xinjiang and Tibet Areas. The prediction effect of W_q value method for M_S6.0 ～6.9 earthquakes in Qinghai,Xinjiang and Tibet area(with hit rate of 61%)was better than that of M_S5.0 ～5.9 earthquakes(with hit rate of 26%). Therefore,the model is significant for the prediction of medium-short term(within one year)strong earthquakes in the area with lower ability of geophysical observation in China.

P315

中国地震局震情跟踪(2022020501)、国家自然科学基金(41704062)和国家重点研发计划(2018YFC1503305)共同资助