门源、江口地震的断层形变前兆分析

ANALYSIS OF FAULT DEFORMATION PRECURSORS OF MENYUAN AND JIANGKOU EARTHQUAKES

在跨断层流动测量的资料处理方面,遇到的一个难题是资料不连续,即观测不是等间隔进行的。因此,现有的数据处理方法无法使用。本文提出了一种处理这种不连续资料的简明方法;用该法处理了位于祁连山断裂带上的部分跨断层测量资料,取得了较好的效果;并根据处理结果分析了1986年在青海省门源县发生的6.4级地震的断层形变前兆。

The discontinuity of data (the interval time of sampling is long and irregular) is one difficulty met in processing the data of the mobile survey across the faults. Therefore, the existing data-processing method can not be used in this field. This paper proposed a simple method for processing the discontinuous data based on the fact that the relative steady-state of the faulting is linear or quasilinear, and the hypothesis that the annual period interference is basically unchanged. Such a method was applied to process part of measured data across the faults located at the fractured zone of Qilian mountain and obtained good results. The analytical results show that there did exist believable fault deformation precursor in the M6.4 Men-yuan earthquake, Qinghai Province, 1986. At Biandukou station, the base line began shortening acceleratively in the second half of 1983 and reciprocal variation of the base line began in May, 1985 and simultaneusly, the levelling showed anomaly; the duration time of precusors is about 3.2 years.