基于Weibull分布地震信息熵对中国大陆西部强震活动状态的分析

State Analysis on Strong Earthquake Activity in West China Continent Based on Seismic Information Entropy of Weibull Distribution

在强震活动轮回和期幕划分等研究中,强震事件的样本数量往往影响并限制了信度和结果外推,特别是强震活动较弱时期对状态的判断将出现较大的不确定性。强震孕育过程中的中小地震活动状态实际上反映了强震活动的规律性。本文采用基于Weibull分布的中小地震信息熵对中国大陆西部的强震活动状态进行分析。结果显示,西部地区目前处在低熵值时段,可能进入新一轮强震活跃期且主体活动区为青藏地块区。在熵值扫描条件相同的情况下,Ⅰ级活动地块内不同Ⅱ级块体的信息熵值时序曲线相似性较大,不同Ⅰ级构造块体内的Ⅱ级块体信息熵值时序曲线差别较大。说明该方法基于统计物理分析,能够反映区域构造特征并克服期幕划分样本数量不足的缺点。

In the study of strong earthquake cycling and periodicity,the sample size of strong events often influence and even limit the reliability and result extrapolation,especially when strong earthquake activity is low,there will be large uncertainty in state judgement.Small-moderate earthquake activity in the seismogenic process of strong earthquakes actually reflects the characteristics of strong earthquake activity.In this article,we analyse the state of strong earthquake activity based on seismic information entropy of weibull distribution for west China continent.The result shows that the entropy value in the west area is low at present,which may mean that the west area is going to enter a new active period of strong earthquakes and the risk site may be in the Qingzang tectonic block.In the same scanning condition of seismic information entropy,the time-curves of different second grade blocks in each first grade block are highly similar,but have large difference among second grade blocks in different first grade blocks.Based on statistical physics analysis,this method can reflect the regional tectonic characteristics and overcome the disadvantage of lack of sample size in division of periodicity.