地震学报（英文版）2009，Vol.22Issue(5)：519-529,11.DOI:10.1007/s11589-009-0519-4
Characteristics of seismic activity before the MS8.0 Wenchuan earthquake
Characteristics of seismic activity before the MS8.0 Wenchuan earthquake
摘要
Abstract
The characteristics of spatio-temporal seismicity evolution before the Wenchuan earthquake are studied. The results mainly involve in the trend abnormal features and its relation to the Wenchuan earthquake. The western Chinese mainland and its adjacent area has been in the seismically active period since 2001, while the seismic activity shows the obvious quiescence of M≥7.0, M≥6.0 and M≥5.0 earthquakes in Chinese mainland. A quiescence area with M≥7.0 has been formed in the middle of the North-South seismic zone since 1988, and the Wenchuan earthquake occurred just within this area. There are a background seismicity gap of M≥5.0 earthquakes and a seismogenic gap of WL≥4.0 earthquakes in the area of Longmenshan fault zone and its vicinity prior to the Wenchuan earthquake. The seismic activity obviously strengthened and a doughnut-shape pattern of M≥4.6 earthquakes is formed in the middle and southern part of the North-South seismic zone after the 2003 Dayao, Yunnan, earthquake. Sichuan and its vicinity in the middle of the doughnut-shape pattern show abnormal quiescence. At the same time, the seismicity of earthquake swarms is significant and shows heterogeneity in the temporal and spatial process. A swarm gap appears in the M4.6 seismically quiet area, and the Wenchuan earthquake occurred just on the margin of the gap. In addition, in the short term before the Wenchuan earthquake, the quiescence of earthquake with ML≥4.0 appears in Qinghai-Tibet block and a seismic belt of ML≥3.0 earthquakes, with NW striking and oblique with Longmenshan fault zone, is formed.关键词
Wenchuan earthquake/ background seismicity gap/ seismogenic gap/ earthquake swarm/ seismic belt/ quiescenceKey words
Wenchuan earthquake/ background seismicity gap/ seismogenic gap/ earthquake swarm/ seismic belt/ quiescence分类
天文与地球科学引用本文复制引用
Yan Xue,Jie Liu,Shirong Mei,Zhiping Song..Characteristics of seismic activity before the MS8.0 Wenchuan earthquake[J].地震学报（英文版）,2009,22(5):519-529,11.基金项目
Acknowledgements This research was supported by the Key Project of Chinese National Programs for Fundamental Research and Development (973 program, No. 2008CB425704 and 2004CB418406). （973 program, No. 2008CB425704 and 2004CB418406）
