中国大陆7级以上地震前地震活动的非线性分析

Nonlinear Analysis on Seismic Activity before M≥7.0 Earthquakes Occurred in Chinese Mainland

本文旨在讨论大地震前地震活动频次的非线性增长现象。首先研究了地震活动的累计增长模型,得到在平稳状态下,小地震的发生近似服从泊松分布的规律,大地震前地震累计频次会出现非线性行为;然后使用中国地震台网中心提供的强震和弱震目录,给出了1970年以来中国大陆15次7级以上地震前地震累计次数呈现指数增长的震例,得到7级以上地震前小震累计次数存在数年尺度的非线性增长特性,部分7级以上地震前小震累计次数还存在几个月尺度的短期非线性特性,应当能够作为一种地震预测的中短期指标。

In this paper we discussed the nonlinear increase feature of seismic activity frequency before large earthquakes.By applying the cumulative growth model of seismic activity we found that the occurrence of small earthquakes approximately obeys Poisson s distribution law in a steady state,in which the cumulative frequency of earthquakes shows non-linear behavior before large earthquakes.Then by using the earthquake catalogues of strong and weak earthquakes from China Earthquake Networks Center,we obtained the exponential growth examples of cumulative number of earthquakes before 15 M≥7.0 earthquakes occurred in Chinese Mainland from 1970.We found that there exists the nonlinear growth characteristic of annual-scale in cumulative number of small earthquakes before M≥7.0 earthquakes.The short-term nonlinear characteristic of monthly-scale existed in cumulative number of small earthquakes before some M≥7.0 earthquakes,which can be used as a short-medium-term indicator for earthquake prediction.