This article applies random function theory, and uses seismic energy released as the basic elements of seismic activity. Using natural orthogonal function (or empirical orthogonal function) expansion method we discussed the short-term time-space anomaly in the energy field of regional seismic activity before the 2008 Wenchuan 8.0 earthquake.The results show that the time weighting factor of eigenvectors (typical field) corresponding to several major features of the field values shows a prominent long-term abnormal change around the source region before the M8.0 earthquake. The time weighting factor corresponding to everal regional characteristic values of energy field along the Longmenshan fault zone shows very obvious short-term anomaly. The authors believe that this method is worthy of further study for prediction of earthquake activity.%本文应用随机函数理论,将地震释放能量作为地震活动场的基本要素,采用自然正交函数(或称经验正交函数)展开方法,讨论了2008年汶川8.0级地震前区域地震活动能量场的中短期时空异常.结果表明,汶川8.0级地震前震源周围区域能量场的几个主要特征值对应的特征向量(典型场)的时间权重因子出现了明显中长期异常变化,这可能是汶川地震中期异常指标;而沿龙门山断裂带能量场的几个区域特征值对应的时间因子出现了显著短期异常变化,这可能是汶川地震短期异常指标.笔者认为该方法是一种值得进一步探讨的地震活动性预测方法.
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