Distributions of Seismicity Parameters and Seismic Apparent Stresses on the Longmenshan-Minshan Tectonic Zone before Wenchuan Earthquake M_S8.0, 2008

详细信息   

• 责任者：Yi Guixi (Earthquake Administration of Sichuan Province ; Chengdu 610041 ; China) ; Wen Xueze
• 刊名：Chinese Journal of Geophysics
• 出版年：2011
• 卷期：54(6)
• 关键词：汶川地震2008 ; Wenchuan earthquake 2008
• 页码：p.1490-1500
• 图表：4 illus., 1 table, 53 refs.
• 分类号：0500
• issnNo：ISSN0001-5733
• isbnNo：CN11-2074/P

摘要

Using the seismic data from the Sichuan Seismic Network, the authors calculate several seismicity parameters on the Longmenshan-Minshan tectonic zone for the last 30 years before the 2008 M_S8.0 Wenchuan, Sichuan Province, earthquake. The authors also calculate the apparent stresses of M_L≥3.5 earthquakes in the study area for the last over 2 years just before the Wenchuan earthquake. Based on the calculations, the authors analyze the relationships between the distributions of the seismicity-parameters and the apparent stresses and both the extent of the Wenchuan mainshock’s rupture and the distribution of the M_S≥5.0 aftershocks. The result mainly shows that: 1) the sections of Mianzhu-Maoxian and Jiangyou-Pingwu of the central and northern segments of the Longmenshan fault zone were of anomalously low b-values that were much lower than the regional mean one, low a-values, relatively high a/b values and relatively short recurrence intervals T_r; 2) following the Wenchuan mainshock, this section has shown relatively low level of aftershock activity without M_S≥5.0 aftershock events; and 3) the difference of the background stress levels on the southwestern and the central to northern segments could be related with the unilateral and northeastward rupture propagation of the Wenchuan mainshock.