During a large earthquake's gestating and occurring process, the stress-strain state along the fault zone has the close relation with the weak seismicity around the fault zone. The seismicity's energy release near the fault zone structure before a earthquake can reflect better the dynamic process of a earthquake's gestating. Thus, in this paper, the method of natural perpendicular function development has been adopted to discuss the time variation about the energy field of the seismic activity along the Longmenshan fault zone before the Wenchuan Afs8. 0 earthquake, 2008. The results have showed that, before the Wenchuan MS8. 0 earthquake, the time factors of the typical field corresponding to several key eigenvalues of the energy field along the Longmenshan fault zone demonstrated a very clear short-term rising, probably as the short-term anomaly message for this earthquake. By analyzing contrastively earthquake examples such as Tangshan earthquake of 1976, the authors believe that studying the time variation of energy field of the seismic activity along the active fault zone can help conduct the intentional and intensive monitor and forecast on the active fault region where is relatively dangerous based on earthquake med- and long-term decision.%在大地震的孕育和发生过程中,沿断裂带的应力-应变状态与断裂带周围微震活动有着密切的关系.震前沿构造断裂带附近地震活动的能量释放更能反映地震孕育的动态过程.本文采用自然正交函数展开方法,讨论了2008年汶川8.0级地震前沿龙门山断裂带地震活动能量场的时间变化.结果表明,在汶川8.0级地震前,沿龙门山断裂带能量场的几个主要特征值对应的典型场的时间因子出现非常明显的短期上升变化,可能是该次地震短期异常信息.通过对比分析1976年唐山地震等震例认为,研究沿活动断裂带地震活动能量场的时间变化,可以对地震中长期判断有较大危险性的活动断裂区进行有目的的重点监测和预测.
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