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汶川地震后沿龙门山裂断带原地应力测量初步结果
引用本文:吴满路,张岳桥,廖椿庭,陈群策,马寅生,吴金生,严君凤,区明益.汶川地震后沿龙门山裂断带原地应力测量初步结果[J].地质学报,2010,84(9):1292-1299.
作者姓名:吴满路  张岳桥  廖椿庭  陈群策  马寅生  吴金生  严君凤  区明益
作者单位:1. 国土资源部新构造运动与地质灾害重点实验室,北京,100081;中国地质科学院地质力学研究所,北京,100081
2. 中国地质科学院探矿工艺研究所,成都,611734
基金项目:科技部973项目,国土资源部《深部探测技术与实验研究》专项(编号 SinoProbe-06)资助的成果 
摘    要:2008年5月12日在中国四川省西部汶川发生Ms8.0地震,震中位于青藏东缘龙门山断裂带。地震发生后的4个月,沿龙门山断裂带中南段开展了原地应力测量,获得了3个测点的应力大小和方向。在3个测孔中浅部采用压磁应力解除法,深部采用水压致裂法。浅部测量结果显示,位于震中区映秀测点,水平最大主应力值为4.3MPa,最大主应力方向为N19°E;宝兴测点位于震中区西南的龙门山断裂带南段,汶川地震没有导致该段地表破裂,该点获得的水平最大主应力值为9.8MPa,最大主应力方向为N51°W;位于龙门山断裂带最西南端的康定测点,水平最大主应力值为2.6MPa,最大主应力方向为N39°E。利用水压致裂法对各钻孔100~400m深度进行了应力测量,获得了应力随深度变化趋势和应力状态。与震前其它应力测量结果和中国其它地区表层地应力测量结果比较,龙门山断裂带西南段处于相对高应力水平,震中区仍处于中等应力水平。这项研究成果将为评价龙门山断裂带余震和今后强震发展趋势提供关键构造物理参数。

关 键 词:汶川Ms8.0地震  原地应力测量  应力解除  水压致裂  龙门山断裂带
收稿时间:2009/4/20 0:00:00
修稿时间:2009/11/27 0:00:00

Preliminary results of in-situ stress measurements along the Longmenshan fault belt after the Wenchuan Ms8.0 earthquake
Zhang Yueqiao.Preliminary results of in-situ stress measurements along the Longmenshan fault belt after the Wenchuan Ms8.0 earthquake[J].Acta Geologica Sinica,2010,84(9):1292-1299.
Authors:Zhang Yueqiao
Affiliation:Institute of Geomechanics, Chinese Academy of Geological Sciences
Abstract:Four months after the Wenchuan Ms 8 earthquake in west Sichuan (China), in situ stress measurements were carried out along the Longmengshan fault zone, with the purpose of obtaining stress parameters for earthquake hazards assessments. In situ stresses were measured in three boreholes by using overcoring of the piezomagnetic stress gauges for shallow depth and hydraulic fracturing for deeper depth. The results show that the maximum horizontal stress at shallower depth (~20m) is about 4.3 MPa, oriented N19°E, in the epicenter area at Yingxiu Township, and about 9.7 MPa, oriented N51°W, at Baoxing County in SW Longmenshan, and about 2.6MPa, oriented N39°E, near Kangding, at the southernmost area of the Longmenshan fault zone. Hydraulic fracturing was conducted at depths from 100 to 400 m and the results show tendency towards increasing in stress with depth. Compared with the results measured before the Wenchuan earthquake along the Longmenshan fault zone and in the Tibetan Plateau, it is concluded that stress level remains relatively high in the southwestern segment of the Longmenshan fault zone, and is still medium in the epicenter zone. These results provide key appraisal for future assessments of earthquake hazards of the Longmenshan fault zone and aftershock occurrences.
Keywords:Wenchuan Ms8  0 earthquake  In-situ stress measurement  overcoring  hydraulic fracturing  Longmenshan fault belt
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