系统梳理2020年6月26日新疆于田6.4级地震构造背景，总结分析余震序列参数演化特征和震前有关异常现象及其预测效能。初步结果如下：①于田6.4级地震发生在黑石北湖断裂附近，主震震源机制显示为张性破裂；②本次地震前原震区发生一次MS 4.6前震，主震后余震相对丰富，构成"前震-主震-余震"型地震序列，震后2个月序列b值为0.71，h值为1.73；③震前震中附近出现准周期活动、地震平静、中源地震影响、多方法组合、垂直摆倾斜和GNSS等中期和短期异常，可能与本次地震的发生存在一定对应关系。
This paper systematically summarized the observed seismicity and geophysical anomalies before Yutian MS 6.4 earthquake in Xinjiang Uygur Autonomous Region on June 26, 2020. In terms of seismicity, some medium-term and short-term anomalies such as seismic quiescence, quasi-periodic seismic activity, images of seismic activities, effects of mid-deep source earthquakes before the occurrence of the Yutian earthquake are observed. In terms of geophysical observations, there are 28 measurements such as gravity, earth tilt, geoelectric field, electric field perturbations, etc. are available within 400 km of the epicenter of the Yutian earthquake and 3 of them are short-term anomalies. The anomalies identified by the comprehensive method are one-year-term. The Yutian earthquake is occurred in the Heishi North Lake fault, which is located in the South area of the Altyn fault. The sequence is foreshock-mainshock-aftershock because there is an MS 4.6 earthquake that occurred before the mainshock and lots of aftershocks occurred within two months. The mainshock source mechanism is tensile rupture. The b value of the sequence is 0.71, and the h value is 1.73. In summary, the seismic anomalies before Yutian MS 6.4 earthquake are mainly medium-term and short-term, and the geophysical anomalies are mainly deformations. The long-term anomalies found before the Yutian earthquake mainly provided the location and magnitude information of the imminent event.
2020,41(5): 168-182 收稿日期：2020-10-10
DOI：10.3969/j.issn.1003-3246.2020.05.022
基金项目：中国地震台网中心青年科技基金（项目编号：QNJJ202011，QNJJ202014，QNJJ202006）；震情跟踪定向工作任务（项目编号：2020010123，2021010502）
作者简介：马亚伟(1990-),男,主要从事地震活动性研究工作。E-mail:yawei_m@seis.ac.cn
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