EFFECTS OF SOURCE PROPERTIES ON CUTOFF FREQUENCY f_(max)

The cutoff frequency f_(max) of radiation from earthquakes is one of the important parameters for studying the source process. By theoretical analysis and numerical experiments on acceleration Fourier spectrum it is suggested that f_(max) mainly depends on the lower values of slip rise time. This result can be used to explain the observational fact that the greater the earthquake magnitude, the smaller the value of f_(max).     

地震孕育过程的流变模式

本文用一个流变介质中平面剪切(Ⅱ型)裂纹的稳态扩展模型,从力学上说明地震的孕育过程及断层的震前蠕动。在整个稳态扩展过程中,断层的蠕动即为震前蠕动。从计算结果得知,唐山地震前可能发生了数量相当可观的震前蠕动。     

震源性质对截止频率f_(max)的影响

地面运动加速度谱的截止频率f_(max)是研究地震震源过程的重要参数之一。本文从理论分析和近场加速度谱的数值实验,论证了f_(max)的数值主要取决于断层面错动时间的下限值。这个结果可以用以解释1976年龙陵强余震的观测事实,即地震的震级越大,f_(max)值越小。     

地球上部对流的研究

板块构造学说成功地解释了板块边缘的各种构造形态,以及海洋盆地演化的一系列现象,显示了地球上的多种构造运动之间存在着必然的内在联系.为了获得对全球构造运动的规律性认识,需要深入研究板块运动的动力学过程.用热对流来研究板块运动的动力来源问题,是其中的一个重要方面.本文简要介绍这方面的研究工作,以期得到力学工作者的关注.     

A RHEOLOGICAL MODEL FOR THE PROCESS OF PREPARATION OF AN EARTHQUAKE

In this paper we try to explain the mechanical aspects of earthquake preparation process and pre-earthquake creep with the steady growth model of an in-plane shear (mode-Ⅱ) crack in rheologic materials. The fault creep which has occurred during the whole period of stable rupture propagation is the pre-earthquake creep. The result of our estimate shows that a considerable pre-earthquake creep had probably occurred before the Tangshan earthquake.