RECENT TECTONIC DEFORMATION ANOMALY AND EARTHQUAKES IN GANSU-NINGXIA-QINGHAI AREA

1　IntroductionAccordingtogeologicalstructure ,theGansu Ningxia Qinghaiareabelongstothenortheastmar ginofQinghai Tibetblock .Thisareahasbeenpaidmuchattentionby geo specialistsinChinaandabroadbecauseofitssignificanttectonicmovement,itsintensiveseismicity ,anditsimportanceinearth quakehazardmitigation .IntheDevelopmentPro gramonNationalKeyBasicResearchesundertheProject“MechanismandPredictionofContinentalStrongEarthquakes”,themechanismsofcontinen talstrongearthquakesarestudied ,usinghypo…

RECENT TECTONIC DEFORMATION ANOMALY AND EARTHQUAKES IN GANSU-NINGXIA-QINGHAI AREA

By processing and analyzing geodetic data of vertical deformation, fault deforma tion and horizontal deformation by GPS in Gansu-Ningxia-Qinghai area and by comparing them with geological structures and many medium to strong earthquake activities in this area, some features of recent tectonic deformation anomaly and the development of medium to strong earthtively large. The amount of vertical movement and the deformation status evolve with time. The dominant stress of tectonic deformation and seismic development in this area comes from the persistent northeastward compression of Qinghai-Tibet block;The time-spatial distribution evolution of tectonic deformation and seismic activities are closely related to dynamic evolution of block moand remarkable fault deformation anormaly on the borders of regional tectonic blocks are indicators of developing moderate-to-strong earthquakes but earthquakes may not necessarily take place in the position of maxium deformation, it usually occurred in the region where fault deformation anormaly shows "trend accumulation-acceleration-turn" variation character or nearby. On the basis of above study, a preliminary prediction for strong earthquake risk in this area is given.