云南红河断裂带北段断裂位错与地震重复发生的时间间隔

本文用地质方法确定了全新世以来红河断裂(北段)位错速率:狭谷段(定西岭)水平位错速率8毫米/年,垂直位错速率1.8毫米/年;宽谷段(大理)水平位错速率5毫米/年,垂直位错速率9毫米/年。据断裂位错参数计算,本区6.8级左右地震重复发生的时间间隔是178±29年;它与6—7级历史地震重复时间间隔150±50年在时间尺度上相当,这对地震中长期预报有参考价值

FAULT DISPLACEMENT AND RECURRENCE INTERVALS OF EARTHQUAKES AT THE NORTHERN SEGMENT OF THE HONGHE FAULT ZONE, YUNNAN PROVINCE

Since the Late Pleistocene, the movement of the northern segment of the Honghe fault zone has been different from that of the southern one. At the southern segment movement is primarily characteristic of single right-lateral shearing, whereas at the northern segment, of a compositive right-lateral shearing with faulted-depressional extension. With in the compositive zone in question appears an en-echolon fault pattern due to alternate shearing and fault-depression. From the southeast to the northwest, they are: Ding Xiling shearing zone, Dali fault-depression,Xiashankou shearing zone, Eryuan fault-depression, Cibihu Lake shearing zone and Jianchuan fault-depression. Geomorphic feature of shear zone and fault-depression is completely different, the former appearing as a narrow valley and the latter, as a basin.This paper is focused on the determination of displacement rates and recurrence intervals of earthquakes of Dixiling shear zone and Dali fault-depression having remained since the late stages of Late Pleistocene. For Dixiling shearing zone, right-lateral displacement rate is 8mm/yr, and vertical slip rate is 1.8mm/yr, with a ratio of 4:1 and for Dili fault-depression, 5mm/yr and 9mm/yr, respectively, with a ratio of nearly 1:2. According to calculations of the parameters of fault displacement,we have found that recurrence intervals for magnitude 6.8 earthquake are 178±29 years. It is consistent with the recurrence interval (150±50 years)of M 6—7 earthquakes from historic seismic records in this area. It may be useful to immediate—long term earthquake predictio