1999 Chi-Chi Earthquake: A Case Study on the Role of Thrust-Ramp Structures for Generating Earthquakes
1999 Chi-Chi Earthquake: A Case Study on the Role of Thrust-Ramp Structures for Generating Earthquakes
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1999 年 Chi-Chi 地震：推力坡道结构在产生地震中的作用案例研究
DOI：
10.1785/0120000731
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发表时间：
2004
影响因子：
3
通讯作者：
Kun
中科院分区：
文献类型：
--
作者：
Wenshan Chen;Bor‐Shouh Huang;Yue‐Gau Chen;Yuan;Chao;C. Lo;Hui;Q. Sung;N. Huang;Chin;S. Sung;Kun
1999年9月21日集集7.6级地震发生在东倾浅层逆冲断层上，产生高起伏地表破裂。出现了异常的地表断裂，可以清楚地追踪到许多县长达100公里的地方。这些逆冲断层，车龙铺和石岗，是与最近持续的弧陆碰撞有关的活动褶皱冲断带的一部分。沿地震破裂的滑动矢量测量表明，车龙铺断裂的最大剪应力方向由西向(N70-90°W)向北西(N30-40°W)方向变化。集集地震时，应力场发生了约40°的顺时针旋转。石岗断裂上盘的近破裂垂直位移比车龙铺断裂具有更大的累积位移，这与全球定位系统(GPS)的测量结果一致。地表破裂和GPS测量发现，破裂上的最大垂直偏移量约为10m。此外，通过对上盘GPS测量的地壳形变分析，确定了与断层斜坡结构有关的同震隆起。
我们对地质和大地测量的综合分析表明了与逆冲断层有关的斜坡构造对大地震的重要性，并为理解褶皱冲断带中的地震提供了一个总体框架。巨大的地表同震隆起和强烈的凹凸体似乎是断层斜坡几何形状的函数。我们的分析还表明，总的来说，褶皱冲断带中的斜坡构造可能具有很高的诱发大地震的潜力。
2000年11月14日收到手稿。
The 21 September 1999 Chi-Chi earthquake ( M w 7.6) occurred on east-dipping shallow thrust faults that produced a high-relief surface rupture. Extraordinary surface breaks appeared that could be clearly traced for about 100 km across many counties. These thrust faults, the Chelungpu and Shihkang, are part of an active fold-and-thrust belt related to ongoing recent arc-continent collision. Measurement of slip vectors along the earthquake rupture indicates that the orientation of the maximum shear stress changed from a westward direction (N70-90°W) on the Chelungpu fault to a northwestward direction (N30-40°W) on the Shihkang fault. The stress field underwent a clockwise rotation of about 40° during the Chi-Chi earthquake. Near-rupture vertical displacements in the hanging wall of the Shihkang fault have more cumulative displacement than on the Chelungpu fault, which is consistent with Global Positioning System (GPS) measurements. Maximum vertical offset on the rupture was found to be about 10 m by the surficial rupture and GPS measurements. In addition, analysis of crustal deformation by GPS measurements on the hanging wall defines a coseismic uplift related to a fault ramp structure.
Our synthesis of geological and geodetic analyses shows the importance of ramp structures associated with thrust faults for generating large earthquakes and provides a general framework for understanding earthquake in fold-and-thrust belts. Large surficial coseismic uplift and strong asperities appear to be a function of fault ramp geometry. Our analysis also indicates that, in general, ramp structures in fold-and-thrust belts may have a high potential in generating large earthquakes.
Manuscript received 14 November 2000.