Characteristics of seismic activity before the MS8.0 Wenchuan earthquake
Yan Xue1, 2, Jie Liu2, Shirong Mei3, Zhiping Song4
1 Institute of Geophysics, China Earthquake Administration, Beijing 100081, China 2 China Earthquake Networks Center, Beijing 100045, China 3 Institute of Earthquake Science, China Earthquake Administration, Beijing 100036, China 4 Earthquake Administration of Shanghai Municipality, Shanghai 200062, China
Characteristics of seismic activity before the MS8.0 Wenchuan earthquake
Yan Xue1, 2, Jie Liu2, Shirong Mei3, Zhiping Song4
1 Institute of Geophysics, China Earthquake Administration, Beijing 100081, China 2 China Earthquake Networks Center, Beijing 100045, China 3 Institute of Earthquake Science, China Earthquake Administration, Beijing 100036, China 4 Earthquake Administration of Shanghai Municipality, Shanghai 200062, China
摘要he 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 ML≥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.
Abstract：he 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 ML≥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.
基金资助:the Key Project of Chinese National Programs for Fundamental Research and Development (973 program, No. 2008CB425704 and 2004CB418406)
通讯作者:
Yan Xue
E-mail: xueyan5619@seis.ac.cn
引用本文:
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.
Yan Xue, Jie Liu, Shirong Mei, Zhiping Song. Characteristics of seismic activity before the MS8.0 Wenchuan earthquake. Earthquake Science, 2009, 22(5): 519-529.
