Slip maxima at fault junctions and rupturing of barriers during the 2008 Wenchuan earthquake
Slip maxima at fault junctions and rupturing of barriers during the 2008 Wenchuan earthquake
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2008 年汶川地震期间断层连接处的滑动最大值和屏障破裂
DOI：
10.1038/ngeo636
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发表时间：
2009-10-01
影响因子：
18.3
通讯作者：
Wang, Qingliang
中科院分区：
文献类型：
--
作者：
Shen, Zheng-Kang;Sun, Jianbao;Wang, Qingliang
2008年5月12日发生在中国的汶川特大地震，让当地人民和科学家都大吃一惊。虽然龙门山断裂带--包括这次地震所沿的断裂带--是众所周知的，但地质和大地测量数据显示相对较低的形变速率(<；3 mm yr(-1))。在这里，我们反演全球定位系统和干涉合成孔径雷达数据，以推断与地震有关的断层几何形状和滑动分布。我们的分析表明，断层的几何形状沿其长度变化：在西南部，断层面向西北方向适度倾斜，而在东北方向则变得接近垂直。与此相关的是沿断层的运动从主要的逆冲运动转变为走滑运动。沿断层的峰值滑动发生在映秀、北川和南坝附近的断层段交汇处，那里是伤亡和破坏的集中地。我们认为，这些位置代表了在单一事件中失效的屏障，使破裂能够级联穿过几个断层段，并引发7.9级大弯矩地震。根据同震滑动分布、大地滑动速率和地质滑动速率，我们估计沿多个节段的屏障和破裂大约每4000年发生一次。
The disastrous 12 May 2008 Wenchuan earthquake in China took the local population as well as scientists by surprise. Although the Longmen Shan fault zone-which includes the fault segments along which this earthquake nucleated-was well known, geologic and geodetic data indicate relatively low (< 3 mm yr(-1)) deformation rates. Here we invert Global Positioning System and Interferometric Synthetic Aperture Radar data to infer fault geometry and slip distribution associated with the earthquake. Our analysis shows that the geometry of the fault changes along its length: in the southwest, the fault plane dips moderately to the northwest but becomes nearly vertical in the northeast. Associated with this is a change in the motion along the fault from predominantly thrusting to strike-slip. Peak slip along the fault occurs at the intersections of fault segments located near the towns of Yingxiu, Beichuan and Nanba, where fatalities and damage were concentrated. We suggest that these locations represent barriers that failed in a single event, enabling the rupture to cascade through several fault segments and cause a major moment magnitude (M-w) 7.9 earthquake. Using coseismic slip distribution and geodetic and geological slip rates, we estimate that the failure of barriers and rupture along multiple segments takes place approximately once in 4,000 years.