2020年1月25日，藏东昌都丁青地区发生5.1级地震，尽管此次地震发生在监测能力较低地区，但震前仍监测到小震调制比高值、低b值等地震活动中短期异常。文中系统总结了地震构造背景、震源物理参数、序列特征以及震前出现的地震活动和地球物理观测等异常，结果发现：震源机制解显示为拉张型破裂，最近断裂为巴青—类乌齐断裂；序列活动特征、序列h值和b值计算结果显示，此次地震为主余型地震序列。目前，藏东地区仍存在一些地震活动和地球物理观测异常，表明该地区存在发生6级以上地震的强震背景，丁青5.1级地震的发生未能缓解该地区强震危险性。
An MS 5.1 earthquake occurred in the Dingqing-Qamdo area, East Tibet on January 25, 2020. Although the earthquake occurred in an area with low monitoring capacity, some short to medium term anomalies such as high modulation ratios of small earthquakes and low b values were still monitored prior to the earthquake. The tectonic background, source physical parameters, and sequence characteristics, as well as seismicity and geophysical observations before the event, are systematically summarized in this paper. The result shows that the source of the Dingqing MS 5.1 earthquake is a tensile rupture and the nearest active fault is Baqing-riwoche fault. The activity characteristics of the sequence and the h value and b value of the sequence show that the Dingqing earthquake belongs to a mainshock-aftershock type. At present, some seismicity and geophysical anomalies still exist in eastern Tibet, indicating that there is still a strong earthquake background with a magnitude of larger than 6, and the Dingqing MS 5.1 earthquake is not sufficient to mitigate the risk of strong earthquakes in this area.
2020,41(3): 162-173 收稿日期：2020-06-10
DOI：10.3969/j.issn.1003-3246.2020.03.021
基金项目：2020年度震情跟踪定向工作任务（项目编号：2020010508）
作者简介：臧阳(1988-),男,主要研究方向:地震活动性和震源物理
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