现今中国东北地区地震活动特征与趋势探讨

A Study on the Present Characteristics and Trends of Seismicity in Northeast China

分析现今中国东北地区地震活动特征,得到几点结论性认识:1)从中国东北地区地震活动期的时间韵律特征和第5活动期的持续时间、地震次数等指标来看,现今中国东北地区地震活动第5活动期已经结束,2018年、2019年吉林松原5.7级、5.1级地震,或标志着中国东北地区进入了第6活动期。2)2013~2019年中国东北地区地震活动主体地区位于松辽盆地和大兴安岭地区,2个地区具有以大兴安岭与松辽盆地的分界线为轴迁移对跳的活动特征。分析5组迁移对跳轨迹认为,未来的地震具有向大兴安岭地区迁移的可能。3)以松辽盆地南缘为界,形成中国东北地区成对地震与非成对地震活动的分界线。1900年以来中国东北地区的成对地震主要发生在松辽盆地和大兴安岭地区,成对地震时间间隔为0.1~37.0个月,距离间隔最远至309.0 km,震级差最大为0.7级。松辽盆地和大兴安岭地区共发生27次5.0级以上地震,其中24次地震具有成对活动性质,成对地震发生率约为89%。成对地震中,发生在松辽盆地的占71%,发生在大兴安岭地区的占29%。成对地震活动规律在松辽盆地和大兴安岭地区具有普适性特征,可作为该区域的预测指标。4)对比2013~2015年和2015~2018年中国东北地区的面应变率结果可见,变化最为显著的区域位于松辽盆地中部,这个区域也是整个中国东北地区变化最为明显的区域,未来仍需关注该区域的地震危险性。5)松辽盆地仍将是中国东北地区浅源地震活动的主体地区。

Based on the analysis of seismicity characteristics in northeast China,the following conclusions can be obtained:1)We should make a concrete analysis from the time prosodic characteristics of the seismicity period in northeast China.The duration of the fifth active period,the number of earthquakes and other indicators,all show that the fifth period of seismic activity in northeast China has ended.The magnitude 5.7 and 5.1 earthquakes in Jilin Songyuan in 2018 and 2019 may mark the beginning of the sixth active period in northeast China.2)The main seismic areas in northeast China are located in Songliao basin and Daxinganling area from 2013 to 2019.The two regions have the activity characteristics of migration pair with the boundary line between Daxinganling and Songliao basin.By analyzing the migration trajectories of five groups,it is possible for future earthquakes to migrate to Daxinganling region.3)The boundary between paired earthquakes and unpaired seismicity in northeast China is formed by the southern margin of Songliao basin.Since 1900,paired earthquakes in northeast China have occurred mainly in Songliao basin and Daxinganling region.The time interval between the paired earthquakes is 0.1 month to 37.0 months,the distance interval is as far as 309.0 km,and the magnitude difference is up to 0.7.A total of 27 earthquakes with a magnitude of 5.0 or above occurred in the Songliao basin and Daxinganling area,among which 24 earthquakes had paired activity and the incidence of paired earthquakes was about 89%.71%of the paired earthquakes occurred in the Songliao basin and 29%in Daxinganling region.The law of paired seismic activity is universal in Songliao basin and Daxinganling area and can be used as a prediction index.4)Comparing the results of surface strain rate in northeast China from 2013 to 2015 and 2015 to 2018,the area of the most significant change is located in the middle of Songliao basin,which is also the area with the most significant change in northeast China.There is a risk of future earthquakes in the area.5)Songliao basin will remain the main area of shallow seismic activity in northeast China.