2003年2月24日巴楚—伽师6.8级地震的构造背景初探

Tectonic Background of the Ms 6.8 Earthquake at Bachu-Jiashi on Feb 24, 2003

20 0 3年 2月 2 4日发生在新疆巴楚的 6 .8级地震造成 2 6 8人死亡。地震发生在塔里木盆地的西北部 ,靠近南天山西段山区的边缘部分。简单来说 ,这次地震仍然是印度板块与欧亚大陆板块碰撞导致的结果 ,尽管板块碰撞的边界线还在远离震区的南面近千公里处。在过去的十年中 ,这次地震所在的伽师地区已经发生过一系列导致伤亡的地震 ,包括 1996年 3月 19日的 6 .7级、1997年 1月 2 1日到 4月 16日发生的 7个 6级地震、1998年 3月 19日 6 .0级、8月 2日 6 .1级和 8月 2 7日 6 .4级地震 ,共造成 4 8人死亡 ,直接经济损失 15亿元人民币。印度板块相对欧亚板块以每年 4 5mm的速率持续向北运动 ,造成了包括喜马拉雅山在内的雄伟山峰 ,并导致了整个青藏高原的隆升 ,地壳应力通过刚性和不变形的塔里木盆地向北传递 ,形成了天山山系并引发了类似这次地震的许多地震。虽然我们目前还不能确定这次地震发生在那条断裂上 ,但是在这一带确有许多类似的断裂存在。

A magnitude 6.8 earthquake occurred on Feb 24 at 2∶3∶44 UTC in Bachu and Jiashi county, killed 268 people. This earthquake occurred near the boundary between the Tarim Basin and the Xinjiang South Tian Shan mountain west range in the north-west Tarim Basin. In a broad sense, earthquakes in this region result from stresses induced by the collision of the Indian and Eurasian continental plates, even though the boundary between these plates lies about 1000 km to the south. The Jiashi region surrounding this earthquake has produced several deadly earthquakes in the past decade. The most destructive earthpuakes include a magnitude 6.7 event on March 19, 1996, seven magnitude more than 6.0 from January 21 to April 16, 1997. Up to August 27, 1998, Eleven earthquakes killed 48 people, and destroyed thousands of buildings. The direct economy losing exceed eleven hundred million Yuan. The Indian Plate continuously moves northward at a rate of 45 mm per year relative to the Eurasian Plate generating massive mountain ranges including the Himalaya and causing the uplift of the Tibetan Plateau. These stresses are transmitted to the north, through the rigid and undeforming Tarim Basin, where they generate the Tianshan mountain and numerous earthquakes like this recent event. Several nearby mapped faults have orientations similar to the fault that the earthquake occurred on, although this quake has not yet associated with a specific fault.