VARIATION OF GRAVITY-FIELD BEFORE AND AFTER
MINXIAN-ZHANGXIAN Ms6.6 EARTHQUAKE
1)Key Laboratory of Earthquake Geodesy,Institute of Seismology,CEA,Wuhan 430071
2)Wuhan Base of Institute of Crustal Dynamics,CEA,Wuhan 430071
3)University of Chinese Academy of Science,Beijing 100039
4)Earthquake Administration of Gansu Province,Lanzhou 730000
Abstract The images of gravity variation before and after the MinxianZhangxian Ms6.6 earthquake,based on gravity data recorded by the gravity net in Gansu province show that,there are some similar characteristics with other earthquakes:1)Before the earthquake,there was a prominent positive gravity anomaly variation amounting to 70×108ms-2 in the south area of the epicenter;2)After the earthquake,gravity variation in the same area was negative,and the positive gravity anomaly variation disappeared.In addition,we found that the calibrate factors of the instruments could affect the result of gravity variation and should be detected and corrected.Our result could provide some reference to research of mechanism of this earthquake.