【摘要】 根据2008年5月12日汶川8.0级地震丰富的余震序列资料,研究了余震活动的时—空扩展过程及分段破裂特征。汶川8.0级地震余震序列呈现有起伏的衰减,前期高频次,衰减快,后期衰减慢,持续时间长。在时间序列出现较强起伏的地震均集中发生在余震带北段,而南段余震活动持续处于平稳状态。密集余震沿NE向龙门山构造带的中央断裂呈窄条形展布330km,深度分布几到40余km。垂向余震带走向(NE方向)的地震深度剖面(NW向截面)和余震密集区图像呈现不对称的锲形分布。这与龙门山推覆构造带的受力作用方式有关。余震区较强余震明显分为南段和北段。研究了较强余震的震源机制及分段特征。给出强余震趋势的基本分析方法,地震类型判定,强余震趋势的阶段性估计效果,以及目前现场地震预报应注意的问题。更多还原

【Abstract】 Based on rich observation data of the 2008 M8.0 Wenchuan Earthquake,we study rupture characters of the faults and the temporal-spatial development of aftershock sequences.The intensity change of aftershock sequences of the 2008 M8.0 Wenchuan Earthquake shows a fluctuate attenuation.In the first half period the attenuation rate of seismic frequency is high and in the later half it is low.The continuation time of seismic attenuation is long.The most of area of seismicity with strong fluctuation is the north segment of seismic fault and the weak seismicity area is the south segment.The aftershock area with heavy intensity distribute along the central segment of Longmengshan faults,which is the seismic belt with 330 kilometers long.The hypocenter depth ranges from several kilometers to 40 kilometers.The vertical profile images formed by the seismic belts of strong aftershocks with the northeast direction show an unsymmetrical wedge distribution.It is relate to the force effecting ways of the nappe structure of Longmenshan faults.The aftershock distribution shows two segments,north and south segments.At the same time,the focal mechanism solutions and the segmental characteristics of strong aftershocks are analyzed.In this paper,we introduce how to judge earthquake tendency,earthquake types,earthquake phases and the tips in the earthquake fieldwork of the 2008 M8.0 Wenchuan Earthquake.更多还原