| Preliminary Results of In-situ Stress Measurements along the Longmenshan Fault Zone after the Wenchuan Ms8.0 Earthquake |
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| 作者姓名： | WU Manlu ZHANG Yueqiao LIAO Chunting CHEN Qunce MA Yinsheng WU Jinsheng YAN Junfeng QU Mingyi |
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| 作者单位： | Key Laboratory of Neotectonic Movement and Geohazard, Ministry of Land and Resources, Beijing 100081; Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081;Key Laboratory of Neotectonic Movement and Geohazard, Ministry of Land and Resources, Beijing 100081; Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081;Key Laboratory of Neotectonic Movement and Geohazard, Ministry of Land and Resources, Beijing 100081; Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081;Key Laboratory of Neotectonic Movement and Geohazard, Ministry of Land and Resources, Beijing 100081; Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081;Key Laboratory of Neotectonic Movement and Geohazard, Ministry of Land and Resources, Beijing 100081; Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081;The Institute of Exploration Technology, Chinese Academy of Geological Sciences, Chengdu, Sichuan 611734;The Institute of Exploration Technology, Chinese Academy of Geological Sciences, Chengdu, Sichuan 611734;Key Laboratory of Neotectonic Movement and Geohazard, Ministry of Land and Resources, Beijing 100081; Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081 |
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| 基金项目： | This study was conducted under the auspice of National Key Basic Project (973) (granted No. 2008CB425702) and National Science and Technology Project (granted No. SinoProbe-06). |
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| 摘 要： | Abstract: Four months after the Wenchuan Ms 8 earthquake in western Sichuan, China, in situ stress measurements were carried out along the Longmenshan fault zone with the purpose of obtaining stress parameters for earthquake hazard assessment. In-situ stresses were measured in three new boreholes by using overcoring with the piezomagnetic stress gauges for shallow depths and hydraulic fracturing for lower depths. The maximum horizontal stress in shallow depths (~20 m) is about 4.3 MPa, oriented N19°E, in the epicenter area at Yingxiu Town, about 9.7 MPa, oriented N51°W, at Baoxing County in the southwestern Longmenshan range, and about 2.6 MPa, oriented N39°E, near Kangding in the southernmost zone of the Longmenshan range. Hydraulic fracturing at borehole depths from 100 to 400 m shows a tendency towards increasing stress with depth. A comparison with the results measured before the Wenchuan earthquake along the Longmenshan zone and in the Tibetan Plateau demonstrates that the stress level remains relatively high in the southwestern segment of the Longmenshan range, and is still moderate in the epicenter zone. These results provide a key appraisal for future assessment of earthquake hazards of the Longmenshan fault zone and the aftershock occurrences of the Wenchuan earthquake.
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| 关 键 词： | Key words: Wenchuan Ms 8.0 earthquake in-situ stress measurement overcoring hydraulic fracturing Longmenshan fault belt |
| 收稿时间： | 2009/4/24 0:00:00 |
| 修稿时间： | 2009/5/11 0:00:00 |
Preliminary Results of In‐situ Stress Measurements along the Longmenshan Fault Zone after the Wenchuan Ms 8.0 Earthquake |
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| Authors: | Manlu WU Yueqiao ZHANG Chunting LIAO Qunce CHEN Yinsheng MA Jinsheng WU Junfeng YAN Mingyi QU |
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| Institution: | 1. Key Laboratory of Neotectonic Movement and Geohazard, Ministry of Land and Resources, Beijing 100081;2. Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081;3. The Institute of Exploration Technology, Chinese Academy of Geological Sciences, Chengdu, Sichuan 611734 |
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| Abstract: | Four months after the Wenchuan Ms 8 earthquake in western Sichuan, China, in situ stress measurements were carried out along the Longmenshan fault zone with the purpose of obtaining stress parameters for earthquake hazard assessment. In‐situ stresses were measured in three new boreholes by using overcoring with the piezomagnetic stress gauges for shallow depths and hydraulic fracturing for lower depths. The maximum horizontal stress in shallow depths (～20 m) is about 4.3 MPa, oriented N19°E, in the epicenter area at Yingxiu Town, about 9.7 MPa, oriented N51°W, at Baoxing County in the southwestern Longmenshan range, and about 2.6 MPa, oriented N39°E, near Kangding in the southernmost zone of the Longmenshan range. Hydraulic fracturing at borehole depths from 100 to 400 m shows a tendency towards increasing stress with depth. A comparison with the results measured before the Wenchuan earthquake along the Longmenshan zone and in the Tibetan Plateau demonstrates that the stress level remains relatively high in the southwestern segment of the Longmenshan range, and is still moderate in the epicenter zone. These results provide a key appraisal for future assessment of earthquake hazards of the Longmenshan fault zone and the aftershock occurrences of the Wenchuan earthquake. |
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| Keywords: | Wenchuan Ms 8 0 earthquake in‐situ stress measurement overcoring hydraulic fracturing Longmenshan fault belt |
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