北天山地震构造特征──航空照片解译

通过对北天山地区1:5万航空照片的解译结果,编制了北天山地震构造图。从中可见北天山新构造活动显著,山前差异运动强烈,活断裂、活褶皱发育,地震频繁。山区因断裂活动产生的山间断陷盆地也是地震活动场所。在近南北向区域应力场作用下,产生的线性构造大体分3组:东西向逆冲断裂;北西、北东向右旋、左旋逆走滑断裂。沿这些断裂,山脊、水系错动,冲洪积扇变形,并分布历史地震、古地震遗迹,可见这些断裂活动性强,多为发震构造。地震常常发生在这些断裂的端点、拐点及两组以上断裂的交汇部位。

AN AERIAL PHOTO INTERPRETATION ON NORTH TIANSHAN SEISMIC TECTONIC CHARACTERS

Through the result of 1 i 50000 aerial photo interpretation for north Tianshan region, the author edited the seismic tectonic map of North Tianshan, from which the obvious neotectonic movement, the strong differential motion of the piedmont, the active faults and folds- generation, as well as the frequency of earthquake occurrence, could be seen easily. The intermountain graben basin that had been formed by the faulting movement was also considered as an active place of seismicity. By the force of the local stress field in rough northsouth directions, some linear structures were appeared and could be divided into three aspects, eastwest thrust faults;northwest, northeast right and left lateral reverse slip faults. Along these fracture ridges, the water system has been dislocated, alluvial and proluvial fans been deformated. The traces of historical and paleo-earthquakes have been discovered now and then. Based on this factor, the author believed that these faults were of strong seismicity, most of their structures were statutory, and earthquakes often visit some places such as the end points, corners and the convergent zones that two or three groups of faults met with.