摘要
20世纪20年代,青藏高原东北发生了两次8级以上强震,其中1920年12月16日发生的海原M8.5地震距今已经100年。海原断裂带作为青藏高原东北缘最活跃的断裂带之一,至今仍控制着该区域微震及中强地震活动。本文基于ISCE软件和StaMPS平台,以2017年3月至2020年6月覆盖研究区的72景哨兵一号(Sentinel-1)SAR影像为数据源,采用PS-InSAR技术对海原断裂带进行时序形变监测,并以区域内GPS速度场进行校正,获取了其三年多来雷达视线向(Line of sight,LOS)的年平均形变速率。研究结果表明:①海原断裂带南北两盘形变速率差异明显,这与左旋走滑的运动性质相符;②毛毛山断裂、老虎山断裂西段处于闭锁状态,老虎山断裂中东段处于较为活跃状态,观测到蠕滑变形;海原地震破裂带部分断裂浅部处于愈合状态;③老虎山断裂中东段的蠕滑变形是青藏高原东北缘最为显著的区段,推断与1888年和1990年景泰的两次六级地震有关。
Numerous deep fault zones have developed in the northeastern Tibetan Plateau,which is the convergence zone of the active Tibetan block,the stable Alashan block,the stable Ordos block,and the stable South China block.Among these fault zones,the Haiyuan fault zone,in which two M8 and several M7 earthquakes have occurred,is one of the most active.Presently,it still controls the activities of strong earthquakes nearby.In this study,based on ISCE and the StaMPS platform,and 72 Sentinel-1 synthetic aperture radar(SAR)images,we monitored the surface deformation of the Haiyuan fault zone by the persistent scatter-interferometric synthetic aperture radar(PS-InSAR)technique,calibrated the initial InSAR result with the GPS velocity field,and finally obtained the annual mean deformation velocity of the Haiyuan fault zone from March 2017 to June 2020.The results revealed the following:(1)The deformation rate on the north and south sides of the Haiyuan fault zone was quite different,which was consistent with the movement characteristics of left-lateral strike-slip faults.(2)The Maomaoshan fault and the western Laohushan fault were locked,and the middle eastern Laohushan fault was fairly active;here,we observed creep deformation.The Haiyuan seismic rupture zone was in a healing state.(3)The creep deformation at the middle eastern Laohushan fault is the most significant section in the northeast margin of the Qinghai Tibet Plateau.We infer that the creeping may be associated with the two M6 earthquakes that happened in Jingtai in 1880 and 1990.
作者
吴东霖
葛伟鹏
魏聪敏
WU Donglin;GE Weipeng;WEI Congmin(Lanzhou Institute of Seismology, CEA, Lanzhou 730000, Gansu, China;Lanzhou National Geophysical Observation and Research Station, Lanzhou 730000, Gansu, China)
出处
《地震工程学报》
CSCD
北大核心
2020年第5期1055-1064,共10页
China Earthquake Engineering Journal
基金
国家重点研发计划项目(2017YFC1500102)
中国地震局科技星火计划项目(XH18048)
甘肃省自然科学基金(17JR5RA340)
中国地震局地震预测研究所基本科研业务专项(2014IESLZ05)
国家自然科学基金(41304035,41572197,41802228)。
