【摘要】 地震震源机制解和地应力实测结果表明,我国大陆地区存在近似于辐射状的区域应力场,其辐射中心位于青藏地块东部.本文首先定义我国大陆应力场近似辐射中心(35°N、100°E)为动力源点,在此基础上计算了1900年以来我国大陆东部地区(30°N—44°N、104°E—125°E)所发生的34次MS≥6.0地震震中到动力源点的距离与地震发生时间的关系.结果表明,20世纪南北地震带中北段发生MS≥7.0地震后,华北地块陆续发生了一系列MS≥6.0地震,且有随时间从南北地震带附近大体向东迁移的规律.据此说明,华北地块的地震主要受控于印度板块作用下青藏地块向我国大陆东部挤压的影响,在其作用下产生了华北地块MS≥6.0地震的系列东向迁移活动.总体来看有4组明显的地震迁移活动,每组地震"序列"的迁移视速度约为80km/a.华北地块首发MS≥6.0地震距南北地震带中北段最近一次MS≥7.0地震的时间间隔约为1个月至11.8年,且60%的MS≥6.0地震发震地点在(39°N±1.5°)区域内.据此推测,2008年汶川MS8.0和2013年芦山MS7.0地震后,华北地块近年存在发生MS≥6.0地震的可能,晋冀蒙交界和环渤海及其附近地区值得重点关注.更多还原

【Abstract】 The focal mechanism solutions of earthquakes and in-situ stress measurement results showed that there was a regional stress field in nearly radial pattern in Chinese mainland,and the radiation center was located in the eastern Qinghai-Xizang(Tibet)block.In this paper we defined the approximate radiation center(35°N,100°E)in Chinese mainland as the dynamic source point and then calculated the distance between the dynamic source point and the location of 34 earthquakes with MS≥6.0since the year 1900 in eastern part of Chinese mainland(30°N—44°N,104°E—125°E)so as to analyze the relationship between the distance and earthquake occurrence time.The results showed that a series of MS≥6.0earthquakes occurred in North China block after an earthquake with MS≥7.0occurred in North-South Seismic Belt in the 20 th century,and they generally migrated eastward from North-South Seismic Belt with time.This also suggested that the earthquakes occurred in North China block should be mainly controlled by the influence of the Qinghai-Xizang(Tibet)block’s squeezing to the eastern Chinese mainland under the action of Indian Plate,causing the MS≥6.0earthquakes eastward migrating in the North China block.There were four distinct groups of migrations with velocity about 80km/a.The interval between the first MS≥6.0earthquake in North China block and the latest MS≥7.0earthquake in North-South Seismic Belt was about 1 month to11.8years,and 60% of the MS≥6.0earthquakes were located in the area close to(39°N±1.5°).Therefore it could be inferred that the MS≥6.0earthquakes probably occur in North China block in recent years after the Wenchuan MS8.0earthquake in 2008 and Lushan MS7.0earthquake in 2013.Accordingly,we should focus on the junction areas of Shanxi,Hebei,Inner Mongolia,and the circum-Bohai and their surrounding areas.更多还原