[S-SS05] [EE] earthquake statistics, physics-based earthquake forecasting, and earthquake model testing

[SSS05-P06] Gravity effect before Lijiang 7.0 earthquake In 1996

*WEIFENG LIANG¹, YIQING ZHU¹, GUOQING ZHANG¹ (1.Second Crust Monitoring and Application Center, China Earthquake Admidistration)

Keywords:gravity change, Lijiang, earthquake

In this study, gravity data before Lijiang 7.0 earthquake in 1996 are adjustmented to a unified benchmark, gravity change image before the earthquake are analyzed, the results show: before the earthquake, during 1989.02-1992.04 (figure a), gravity cumulative changes smoothly, and within 30 x 10^-8 ms^-2; During 1992.04-1995.04 (figure b), gravity cumulative change is very severe, in the process of that gravity changes from positive to negative from south to north, by the trend in the northern part of the studied area appeared 70×10^-8ms^-2 local gravity anomaly zone, abnormal zone diameter greater than 150 km. From the perspective of a 6 years scale 1989.02-1995.04 (figure c), the gravity accumulation of positive - negative differences still exist, gravity cumulative change is more intense, and along the line crossing Eryuan, Dali, and Midu, the gravity change with positive and negative differences, positive and negative difference maximum 150×10^-8ms^-2; During 1995.04-1996.02 (figure d), the gravity changes reverse, the earthquake occur in the process of reverse gravity changes.