对1812年3月8日新疆尼勒克8级地震发震构造的初步探讨a

本文根据现场考察,航片解译和历史记载资料,对1812年3月8日尼勒克地震的震级及地震地质背景进行了讨论。根据地震主断裂带的展布和运动特征与喀什河断裂带相一致等特点,指出1812年尼勒克8级大震是喀什河断裂作右旋逆冲的结果。 喀什河断裂是一条控制伊犁盆地北界和喀什河河谷的活断裂,它错断了喀什河阶地和古尼勒克沟,有着明显的新活动性。在震区还发现了一些古地震遗迹。对比1812年地震陡坎和古地震陡坎角度变化情况,对断层运动速率进行了估计,并估算出喀什河断裂带发生M8地震的重复周期为800——1600年。

A PRELIMINARY STUDY ON THE ORIGINAL TECTONICS OF THE NILK QUAKE (M=8) IN XINJIANG OCCURRED ON MAR. 8, 1812

Based on the field investigation,the interpretation of aerial photographs and the historical data,the magnitude of the Nilk quake on Mar. 8,1812,and its seismologeolog-ical background have been discussed. It indicates that the quake is the result of the dextral overthrust of the kashi River Fault for its main fault distribution and motion character consistent with that of the Kashi River Fault Zone.'The Kashi River Fault is an active fault,which controls the north boundary of the Yili-Basin,and the Kashi River Valley,and it also truncate the Kashi River terrace and the palaeo-Nilk gully,until now it is still in activity. We are found some trails of the palaeo-earthquake in this region. By comparing the variation of the scarps occurred in the quake of 1812,with that of the fault surface occurred in the palaeo-earthquake and its ratio of the fault motion,the present result indicates that the recurrence period of the Nilk quake (M=8) is 1200400 years.