一九三七年青海托索湖7.5级地震形变带特征

1937年1月7日青海托索湖7.5级地震形变带长达300公里,总体走向北70°西,与库赛湖—玛曲断裂带展布完全吻合。该形变带由一系列陡坎、鼓包、张裂缝、鼓梁和陷坑组成。各种形变现象的组合显示发震断裂具压扭(反时针扭动)特征。反映了震区应力场主压应力方向为北东东—南西西向。由于主要以隆起、凹陷形式出现的北北西向构造在震区和北西西向的库玛断裂反接复合,为库玛断裂反时针错动造成阻抗,引起应力在此大量积聚。这是导致这次大震发生的根本原因。

CHARACTERISTICS OF DEFORMATION BAND OF THE 1937 TUOSUOHU EARTHQUAKE (M=7.5) IN QINGHAI

The deformation band of Tuosuohu earthquake Jan. 7, 1937(M=7.5) was 300km long. Strike as a whole was N70°W, in keeping with Kusaihu and Maqu fracture zone. This deformation band consists of a series of fault scarps, little upheavals, tension fissures, fault ridges and small segs. The combination of all deformation phenomena has shown that earthquake fracture is compressional with anticlockwise torsion characteristics and that the direction of compressional stress of earthquake region stress field is NEE-SWW. The structure of upheavals and segs of NNW direction, has intersected with the fracture Kuma in the earthquake region. The said structure has impeded the anticlockwise torsion of the fracture Kuma. Stresses have been congregated here. That was the essential cause which led to the occurrence of this strong earthquake.