基于地壳双层结构假设的大陆强震孕震机制探讨

通过对地壳低速高导层和地震震源深度等有关资料的分析研究,在对地震发生前兆、特征及物理机制研究的基础上,初步提出了一个简单的地壳双层孕震模式:地壳存在有两层孕震结构,上层为主孕震层,是地震应力集中积聚和发震后释放应变能的地方,主要是岩石发生脆性变形层,深度在中上地壳范围内;下层为低速高导层,是诱发和加强上层脆性层岩石变形、应变能积累和破裂的主要因素之一,处于岩石脆—韧性变形的过渡带,强震的发生与本层有着密切的关系,深度在中下地壳范围内。同时基于该双层孕震假设讨论了强震的孕育环境及作用。

Discussion on Seismogenic Mechanism of Continental Strong-shocks Based on the Hypothesis of Double-storey Pattern for the Crust

Through detailed analyses for available data concerning low-velocity and high conductive layer beneath the crust and seismic depths,based on the studying of seismic precursors,characteristics and physical mechanisms,a simple double-storey seismogenic hypothesis of the crust for continental strong shocks is preliminarily presented in this paper.The upper layer in mid-upper crust is main earthquake pregnant layer where stress concentrats and strain energy releases in earthquakes events,and is a brittle deformation layer of rocks.The lower one in mid-lower crust with high conductive and low velocity of P wave,is believed that it is one of the most important factors inducing and enhancing brittle deformation,strain energy cumulation and crack in the upper rocks.The latter layer locates in a transitional zone of rock deformation from brittle to ductile,which is closely associated with the occurrence of strong shocks.Meanwhile,seismogenic environment and significance for strong shocks based on the double-storey pattern are discussed in paper.