汶川5.12地震引起的库仑应力变化及其对周边地震活动的影响

王连捷; 周春景; 孙东生; 吴珍汉; 王薇

汶川5.12地震引起的库仑应力变化及其对周边地震活动的影响

国土资源部新构造运动与地质灾害重点实验室, 中国地质科学院地质力学研究所, 北京 100081

基金项目:

中国地质科学院基本科研业务费专项 Ywf060717

地质力学所基本科研业务费 DZLXJK200705

详细信息

作者简介:
王连捷(1933-), 男, 研究员, 从事地质灾害、地应力测量、应力场数值分析及应用研究。E-mail:wanglj01@sina.com

中图分类号: P315.72⁺7
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出版历程
- 收稿日期: 2008-09-28
- 刊出日期: 2008-09-01

COULOMB STRESS CHANGES CAUSED BY WENCHUAN EARTHQUAKE AND ITS INFLUENCE ON SEISMIC ACTIVITY IN THE ADJACENT AREAS

Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China

摘要

摘要: 汶川"5.12"8.0级特大地震, 造成重大人员伤亡和财产损失。地震对周围地区断层活动性的影响和余震发展方向是人们关心的一个问题。根据汶川地震同震静态位移我们计算了周围地区一些断层的库仑应力变化, 并据此评价了震后周围地区断层和地震的活动性。计算结果表明, 龙门山断裂带东北段, 包括北川、青川、宁强等地, 为库仑应力增强区, 有利于地震的发生。较大的余震分布与库仑应力增强区有较好的对应关系。鲜水河断裂带主要为库仑应力下降区, 只有一小段为增高区, 鲜水河断裂带总体上不利于地震活动。成都地区的西北部库仑应力增强, 东南部应力下降。库仑应力变化的研究对大震后地震趋势的分析有重要意义。
- 汶川地震 /
- 库仑应力变化 /
- 龙门山断裂带 /
- 有限元
Abstract: On 12 May 2008, M8.0 Wenchuan earthquake occurred along the Longmenshan fault belt in Sichuan Province of China, causing enormous losses and thousands death, and the rearrangement of crustal stress commonly leads to damaging aftershocks.Coulomb stress changes caused by the Wenchuan earthquake are calculated and earthquake activity is evaluated using finite element method for some faults around the area.Results show that Coulomb stress displays a greater changes in northeast part of Longmeshan fault belt, including Beichuan, Qingchuan, Ningqiang areas and so on.Most of aftershocks of Wenchuan earthquake occurred in the area where the Coulomb stress change is increased. Coulomb stress gets weaker in most parts of Xianshueihe fault (b-1, b-2, b-4)except for some parts (b-3).It shows an increase to northwest of Chengdu, but a decrease to southeast of Chengdu.Coulomb stress increases can bring faults to failure, with delays ranging from seconds to decades.
- Wenchuan earthquake /
- Coulomb stress change /
- Longmenshan fault /
- finite element
注释:
编者按:
本文根据汶川地震同震静态位移计算了周围地区一些断层的库仑应力变化, 并据此评价了震后周围地区断层和地震的活动性, 结果表明较大的余震分布与库仑应力增强区有较好的对应关系。从力学的角度深入解释了余震的发生机理, 对研究汶川大震后地震的发展趋势有重要意义, 值得一读。

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图 1 简化的活动断裂分布

Figure 1. A sketch showing distribution of active faults

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图 2 有限元网格划分

Figure 2. Division of finite element mesh for calculation

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图 3 地震位错模型(沿断层面的位移) ^①

Figure 3. Model of displacement of Wenchuan earthquake^①

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图 4 沿断层走向的地表位移(正值表示沿断层向NE方向位移, 负值表示沿断层向SW方向位移)

Figure 4. Surface displacement along strike of Longmenshan fault from Wenchuan earthquake (positive shows northeast displacement, negative shows southwest displacement)

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图 5 垂直断层走向的位移(正值表示垂直于断层向NW方向位移, 负值表示垂直于断层向SE方向位移)

Figure 5. Surface Displacement perpendicular to strike of Longmenshan fault from Wenchuan earthquake (positive shows northwest displacement, negative shows southeast displacement)

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图 6 垂向位移(正值表示向上, 负值表示向下)

Figure 6. Vertical displacement from Wenchuan earthquake (positive shows displacement up, negative shows displacement down)

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图 7 四川及其他地区库仑应力的变化和汶川地震后5级以上余震分布

1.断层; 2.5级以上余震; 3.库仑应力增加区; 4.库仑应力变化不明显地区(< 0.01 MPa); 5.库仑应力降低区; 6.震中

Figure 7. Coulomb stress changes and distribution of aftershocks (more then M5) in Sichuan and other areas after the Wenchuan earthquake

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图 8 沿断层面库仑应力变化的分布(库仑应力变化单位MPa)

Figure 8. Distribution of Coulomb stress changes along fault plane after Wenchuan earthquake

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