Abstract:Variations of the gravity and the ground density of Nepal and its surrounding area are calculated from the GRACE satellite gravity observations; furthermore, the time series of gravity changes at typical points around seismic sources in the region are also obtained. The results show that the obvious negative gravity change rate is concentrated in the Himalaya and Burma arc regions, while the internal Tibetan plateau, northern India and the eastern Southern China block mainly present the significantly positive gravity change rate. The Nepal earthquake occurred in the transfer zone between the positive and the negative gravity changes. The gravity change rate has obvious time segmentation features during 2015: gravity changes decreased from January to April, increasing from May to September, but the gravity changes gradually recovered to increased tendency after December, 2015. Time series of typical points reveals that the gravity around the seismic sources region of the Nepal earthquake overall show long-time decreased feature, the gravity change rates mainly present the characteristics of “increase-decrease-increase-earthquake occurred-decrease” from 2013 to 2016. The changes of the ground density can well reflect the relationship between the ground mass migration and the gravity change rate, which also provides an important reference for understanding the dynamic mechanism of the Nepal earthquake.
QU Wei,AN Dongdong,XUE Kang et al. Gravity Variations before and after the M8.1 Nepal Earthquake Observed by the GRACE[J]. jgg, 2017, 37(12): 1214-1218.