地震活动性参数的变尺度(R/S)分析

RESCALED RANGE (R/S) ANALYSIS ON SEISMIC ACTIVITY PARAMETERS

将改变时间标度的方法应用于地震活动性分析中 ,选择具有不同空间尺度范围、时间范围和地震活动背景的现代仪器地震目录作为研究对象 ,分析了几个地震活动性参数地震频度和地震发生时间间隔与时间标度的关系 .这些地震活动性参数的极差和均方差之比与时间标度呈现出幂指数变化方式 ,且幂指数都大于 0 .5,表明地震的发生并非无记忆的泊松过程 ,而是具有随机和规律的双重特性 .H指数偏离 0 .5的程度可以衡量随机与规律成分所占比重 ,偏离越大 ,该序列的规律性成分越多 ,反之则越少 .通过时间标度变换 ,可以较短时间的观测为基础 。

The rescaled range (R/S) analysis, proposed by Hurst, is a new statistical method. Being different from traditional statistical method, R/S analysis can provide the information of maximum fluctuation (range) of statistical parameters. At present paper, several modern instrumental earthquake catalogues in different spatial scale, temporal scale, and with different seismic activity background are studied, and R/S method is used to analyze the variation of range of seismic parameters such as earthquake frequency, and earthquake time interval. For different seismic parameters, the ratio of range to standard deviation - R/S is a power law function of the length of time, and the exponent H of power law is always greater than 0.5. As we know, H=0.5 is the characteristics of all ideal random processes. Our results indicate that earthquake series is not an ideal Poisson process, on the contrary, the earthquake as a phenomenon bears dual characteristics of randomicity and regularity, and the greater H departs from 0.5, the more regularity the time series will show, and vice versa. With time scale changing, one can give the conservative estimate of the fluctuation, which might occur in a relatively long time scale, only by using the limited and known time records.