地震预报的新途径--加卸载响应比理论

从力学角度看,地震的孕育过程实质上是孕震区介质的损伤演化过程,这个过程主要是一个力学过程．但解决与地震预测有关的力学问题与工程中的力学问题有许多不同之处．通常力学问题的解决需要知道其本构关系、边界条件、初始条件以及某些力学量的变化历史(如流变)．但是在地震孕育过程中它们却是未知的或不完全知道的．人们知道的只是地壳中某些物理量的变化．由此提出了加卸载响应比作为一种地震预测的新途径,并简述了加卸载响应比的基本概念、实际应用及一些最新结果．     

非线性系统失稳的前兆与地震预报——响应比理论及其应用

本文在分析了不同的非线性系统的失稳过程后得出:其失稳前兆为响应率不断增高或响应比不断增高,而且系统临近失稳时加载与卸载的响应是不同的.将这一理论用于地震预报.利用起潮力引起的地壳中应力的周期性变化,作为加、卸载的手段.如能分别测量出固体潮加载周期与卸周期引起的响应(如地形变、重力、地震活动性等)的比值,这一参量必然包含地震孕育的特征信息. 用1970—1988年间发生在中国大陆的9个M≥7的大地震的资料,将该区域内中小地震所释放的能量的平方根(Benioff称之为释放应变)作为固体潮加卸载的响应,9个地震中的7个,在震前其响应比明显增高.     

THE PRECURSOR OF INSTABILITY FOR NONLINEAR SYSTEMS AND ITS APPLICATION TO EARTHQUAKE PREDICTION

By analysing the instability process of various nonlinear systems, we conclude that their instability precursors are the continual heightening of the response rate or response ratio.Applying this theory to earthquake prediction, we adopt the periodical change of the stress in crust caused by the tide-generating force as the loading and unloading. If we can measure the ratio of the response (such as crust deformation, gravity and seismicity) during the loading period to that during the unloading period, this parameter must contain some characteristic information about the seismogenic process.With nine earthquakes (M≥7) data that occurred in Chinese mainland during 1970-1988, we take the sum of square root o?energy of small earthquakes, which is called the released strain by Benioff, as the response to the tidal loading and unloading. We find that the response ratios of seven earthquakes increase obviously before the main earthquakes.     

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。     

走进地震预测——————加卸载响应比方法

 概括介绍了加卸载响应比的基本思路、基本概念、物理基础、加卸载 响应比在地震预测中的应用以及取得的一些成果. 加卸载响应比方法物理基础扎实, 只需利 用地球内部的某些实测数据, 为地震预测提供了一条新的途径.     

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.     

从临界转变的角度理解地震预测技术

侦测重大地震前相关的地震活动度异常,以此作为地震预测基础理论的研究,在近十年内常被提出讨论.其中有两个典型的算法,包括美国加州Rundle教授的“震模信息学”算法和北京尹祥础教授的“加卸载响应比值”算法.前者旨在揭示地震活动度的高异常变异性;后者则藉助于日、月引力的响应,来研究地壳块体的受损程度.文章从“临界转变理论”出发,认为不管是高异常地震活动度变异,或是象征地壳材料已严重受损的高加卸载响应比值,都是地壳即将出现临界转变(亦即重大地震)的早期征兆.也就是说,原由两个独立研究群体提出的地震活动度算法,实为临界转变的前兆信号的一体两面,可以在临界转变理论下统一起来.