Earthquake triggering along the Xianshuihe fault zone of Western Sichuan, China
Earthquake triggering along the Xianshuihe fault zone of Western Sichuan, China
复制标题
DOI：
10.1007/s00024-003-2471-4
复制
发表时间：
2004-08-01
影响因子：
2
通讯作者：
Jin, XS
中科院分区：
文献类型：
--
作者：
Papadimitriou, E;Wen, XZ;Jin, XS
川西是中国西南地区地震活动最为活跃的地区之一，其特点是频繁发生强烈（震级M≥6.5）地震，主要沿鲜水河断裂带分布。历史地震活动和仪器记录的地震活动显示出活跃期和不活跃期交替的时间模式，同时在空间上观察到震中显著迁移。在始于1893年的上一个活跃期，全长350公里的左旋走滑鲜水河断裂完全破裂，连续强震的震中沿其走向迁移。通过求解1893年以来的库仑破裂函数（ΔCFF）变化，进而研究该地区过去110年应力场的演化，对这种模式进行了研究。库仑应力变化的计算假设地震可以模拟为弹性半空间中的静态位错，并考虑到强震（震级M≥6.5）中的同震滑动以及与主要断层段相关的缓慢构造应力积累。针对与强震事件相适应的走向、倾角和滑动角的断层进行了应力变化计算。我们评估这些应力变化是使给定的强震更接近还是更远离破裂。研究发现，所有强震，而且大多数有可靠断层面解的较小地震事件，都发生在应力增强的断层段上，这提供了一个令人信服的案例，说明库仑应力模拟能够深入了解地震活动的时空表现。我们将应力计算延伸到2025年，并通过确定可能发生未来强震的断层段，对未来地震危险性进行了评估。
Western Sichuan is among the most seismically active regions in southwestern China and is characterized by frequent strong (M greater than or equal to 6.5) earthquakes, mainly along the Xianshuihe fault zone. Historical and instrumental seismicity show a temporal pattern of active periods separated by inactive ones, while in space a remarkable epicenter migration has been observed. During the last active period starting in 1893, the sinistral strike-slip Xianshuihe fault of 350 km total length, was entirely broken with the epicenters of successive strong earthquakes migrating along its strike. This pattern is investigated by resolving changes of Coulomb failure function (DeltaCFF) since 1893 and hence the evolution of the stress field in the area during the last 110 years. Coulomb stress changes were calculated assuming that earthquakes can be modeled as static dislocations in an elastic halfspace, and taking into account both the coseismic slip in strong (M greater than or equal to 6.5) earthquakes and the slow tectonic stress buildup associated with major fault segments. The stress change calculations were performed for faults of strike, dip, and rake appropriate to the strong events. We evaluate whether these stress changes brought a given strong earthquake closer to, or sent it farther from, failure. It was found that all strong earthquakes, and moreover, the majority of smaller events for which reliable fault plane solutions are available, have occurred on stress-enhanced fault segments providing a convincing case in which Coulomb stress modeling gives insight into the temporal and spatial manifestation of seismic activity. We extend the stress calculations to the year 2025 and provide an assessment for future seismic hazard by identifying the fault segments that are possible sites of future strong earthquakes.