Abstract:

Based on the interpretation of satellite images,combined with field geomorphic and tectonic investigations and surveys,we get the parameters of surface rupture zones of the 1895 Tashkorgan earthquake,such as the geometry,the types of rupture,the displacements and their distribution and so on.And on these grounds,we estimate the possible magnitude,the epicenter and seismogenic fault of this earthquake.The south segment of Muztag Fault and the whole Taheman Fault were ruptured by the Tashkorgan earthquake.The length of the surface rupture zone is 27km.The rupture zone strikes NNE,and it changes from N25°W in the north to N25°E in the south segment.The surface rupture zone is composed of consequent or obsequent normal fault scarps,represented by horst,graben,and step-like structure on the profile,and distributed in patterns as en echelon,parallel,convergent and parallel cross shaped and so on in the plane.The surface ruptures are dominated by pure dip-slip,with little lateral displacement.The general width of these overlapping surficial fault rupture strands is ca.30～60m, and the largest may come to 825m.The largest co-seismic displacement of a single scarp is 4.2±0.2m. The surface ruptures are composed of three independent secondary segments.The seismogenic fault of this earthquake is Taheman Fault.The south segment of Muztag Fault was also ruptured.Moreover,we find a younger fault scarp which may be induced by the 1895 earthquake in the small basin between the two above-mentioned faults.

Key words: Tashkorgan earthquake, normal fault, surface rupture, rapture segmentation, seismogenic fault, Pamir

摘要：

基于高分辨率卫星影像解译,通过野外地质地貌填图与差分GPS测量,初步获得了帕米尔高原1895年塔什库尔干地震地表破裂带的空间展布、破裂类型、位移及分布等基本参数,据此估算了可能的地震震级,讨论了其宏观震中及发震构造模型。塔什库尔干地震使得慕士塔格正断层南段的部分和整个塔合曼正断层发生破裂,形成了长约27km的地震地表破裂带,破裂带总体走向NNE,由北部的N25°W向南转至N25°E。地表由正向或反向正断层陡坎组成,在剖面上表现为地堑、地垒和阶梯状等构造组合; 在平面上表现为单条雁列型、平行型、收敛(或汇聚)型、"井"字型等。地表破裂带以纯倾滑为主,基本无走滑量,表现为正断层性质。地表破裂带一般宽30～60m,最大可达825m; 单条陡坎垂直位移(4.2±0.2)m,最大同震垂直位移6.8m。地表破裂具有明显的破裂分段特征,由北向南由3条独立的次级破裂段组成。估算其地质矩震级为7.0～7.3级。该断层以东的小盆地内发现了同震感应地表破裂。

关键词: 塔什库尔干地震, 正断层, 地表破裂带, 破裂分段, 发震构造, 帕米尔高原