COULOMB STRESS CHANGES CAUSED BY WENCHUAN EARTHQUAKE AND ITS INFLUENCE ON SEISMIC ACTIVITY IN THE ADJACENT AREAS
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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。
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.
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Key words:
- Wenchuan earthquake /
- Coulomb stress change /
- Longmenshan fault /
- finite element
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