2020年3月23日新疆拜城5.0级和7月13日霍城5.0级地震总结

2020年3月23日和7月13日，新疆天山中部地区分别发生拜城5.0级和霍城5.0级地震，其中拜城5.0级地震发生在南天山地震带中段，霍城5.0级地震发生在北天山地震带西段。系统总结2次地震前出现的地震活动和地球物理观测异常，结果表明：①拜城5.0级地震：震前主要存在5级地震成组和尼勒克钻孔应变中短期异常；②霍城5.0级地震：震前中短期异常比较丰富，存在3级以上地震带状分布、地震发生率指数、D值、调制比、b值异常，而地球物观测则以形变异常为主，主要出现在震中附近区域。综合分析认为：①拜城5.0级地震前地震活动异常较少，地球物理观测以趋势异常为主，短期指示意义不明确；②霍城5.0级地震前具有中短期预测意义的地震活动和地球物理异常较为丰富，为后续中强地震的发生提供了判定依据。

About Baicheng MS 5.0 earthquake on March 23 and Huocheng MS 5.0 earthquake on July 13, 2020, in Xinjiang

On March 23 and July 13, 2020, two M_S 5.0 earthquakes occurred in the central Tianshan zone of the Xinjiang region. The Baicheng M_S 5.0 earthquake occurred in the middle section of the southern Tianshan seismic belt, and the Huocheng M_S 5.0 earthquake occurred in the western section of the northern Tianshan seismic belt. In this paper, the seismicity and geophysical observation anomalies before the two earthquakes are systematically summarized, and the results are as follows:there are mainly M_S ≥ 5.0 earthquake grouping and middle to short-term anomalies of borehole strain at Nilka station before Baicheng earthquake. The medium-term and short-term seismic and geophysical anomalies are abundant before the Huocheng earthquake, such as seismic belt with a magnitude of M_S 3.0 and above, earthquake rate index, D-value, earth tidal modulation ratio, and b-value. In terms of geophysical observation, there are mainly crustal deformation anomalies near the epicenter of the two earthquakes, including 9 deformation and 1 electromagnetic anomaly that are mainly distributed near the epicenter of the Huocheng earthquake. According to the comprehensive analysis, there were few seismicity anomalies before the Baicheng earthquake. The geophysical observations were dominated by trend anomalies, and their short-term indications were not obvious. Compared with the Baicheng earthquake, there were abundant seismicity and geophysical anomalies before the Huocheng earthquake, these anomalies have short-term to medium-term predictive meanings for the occurrence of future moderate to strong earthquakes in the local areas.