Relations between gravity variation of Longmenshan fault zone and Wenchuan M_S 8.0 earthquake

Abstract

The observed results of repeated absolute and relative gravity measurements in Chengdu arear during 1996 - 2008 are systemically analyzed, and then discuss the relationship between gravity variation of Longmenshan fault zone and Wenchuan M_S 8. 0 earthquake. The results show as follows. ①The change of gravity field is closely relative to tectonic movement of Longmenshan fault zone. The change of surface gravity field caused by the active faults associated with the mass transfer and structural deformation can be effectively reflect by gravity measurements.② The dynamic images of gravity field in Chengdu arear base on absolute gravity measurements can express the precursory gravity information during the seismogenic process of the Wenchuan M_S 8. 0 earthquake.③The temporal changes' value of gravity point (Yingxiu, Beichuan) cumulate to 120 ×10~(-8)m #8226; s~(-2) shows that gravity field near meizoseismal region have fast increased after the Wenchuan M_S 8. 0 earthquake. #169;Before Wenchuan earthquake, the gravity anomaly in the Sichuan Basin on the east side of Longmenshan fault zone is relative stability, and the gravity anomaly in the West Sichuan Plateau on the west side of Longmenshan fault zone is significant changes.