Temporal and Spatial Variation of Apparent Stress in Sichuan Area before the MS 8.0 Wenchuan Earthquake
详细信息
- 责任者：Li Yan’e (Institute of Geophysics ; CEA ; Beijing 100081 ; China) ; Chen Xuezhong
- 刊名：Earthquake
- 出版年：2012
- 卷期：32(4)
- 关键词：汶川地震2008 ; Wenchuan earthquake 2008 ; 地应力 ; geostress ; 四川 ; Sichuan Province
- 页码：p.113-122
- 图表：4 illus., 26 refs.
- 分类号：0500
- issnNo：ISSN1000-3274
- isbnNo：CN11-1893/P
摘要
LIGN: left; WIDOWS: 2; TEXT-TRANSFORM: none; BACKGROUND-COLOR: rgb(244,244,244); TEXT-INDENT: -5px; LETTER-SPACING: normal; DISPLAY: inline !important; FONT: 12px/22px Arial, 宋体; WHITE-SPACE: normal; ORPHANS: 2; FLOAT: none; COLOR: rgb(36,36,36); WORD-SPACING: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px">On the condition of near-source, the Brune model was employed to determine the apparent stress of 439 earthquakes with ML≥3.0 occurred in Sichuan during May 2000 to April 2008 with seismic waveform data recorded by the regional digital telemetric seismic networks in Sichuan area. The spatial distribution image of the apparent stress in Sichuan before the MS8.0 Wenchuan earthquake on May 12, 2008 had been given,and the variation process of the apparent stress with time in Sichuan, the Longmenshan Fault Zone and the dense zone of small earthquakes in the Longmenshan Fault Zone was analyzed. The results were as follows: 1) high apparent stress was mainly concentrated in the Sichuan-Yunnan boundary region before the Wenchuan earthquake; 2) variation of the apparent stress with time in Sichuan from 2001 to 2006 showed a process of abrupt rise and fall,and the high-value points of the apparent stress increased gradually; 3) apparent stress in Longmenshan Fault Zone showed an obvious increase-decrease process from the midyear of 2004 to the beginning of 2005. The variation of Dsapp value which showed two increase-decrease processes was relatively complex; and 4) apparent stress in the dense zone of small earthquakes in the Longmenshan Fault Zone showed two obvious increase-decrease processes from 2003 to 2005, and increased abruptly before the main earthquake.