Abstract: The structural media,internal and external environments of intracrustal seismogenic layer are the important factors which constrain the generation and occurrence of earthquakes,especially strong ones in this layer. Till now,the main advances of studies on the earthquake generating environments of seismogenic layer are as follows: Seismogenic layer is located at the lower part of upper crust to mid crust with the assemblage of amphibolite facies (greenschist facies at upper part of this layer) metamorphic and granitic rocks. It is a medium layer with the relatively high seismic velocity,high density and high resistivity and its lower part corresponds to the transition zone of brittle ductile deformation and high shear stress zone. Intracrustal low velocity high conductivity layers exist below this zone or strong seismic sources. The stress field in this layer is characterized by regional variation and the cut off temperatures for intracrustal seismicity range 300℃～400℃. Seismic source faults are characterized by regional variation and may have different earthquake generating mechanisms for different region. To a certain extent,the strong body earthquake generating model may be useful for the efforts of earthquake prediction.

Key words: Earthquak structure, Earthquake-generating model, Intracrustal seismogenic layer

摘要： 壳内多震层的介质结构及其内、外环境是制约地震(尤其强震)在该层内孕育、发生的重要因素。现今多震层孕震环境研究所取得的主要进展如下:多震层位于上地壳下部至中地壳,岩石组合为角闪岩相(上部为绿片岩相)变质岩和花岗质岩石;多震层具有相对高速、高密度、高阻的介质结构,其下部对应脆 韧变形转换带和最大剪切应力带;多震层(或强震震源)之下存在壳内低速 高导体;多震层应力场具有区域性分区特点,壳内地震活动截止温度约300～400℃;多震层内震源断层具有区域性特点,不同地区震源断层可能具有不同的孕震机制;“坚固体孕震模式”对地震预报具有一定的指导作用。

关键词: 地震构造, 孕震模式, 壳内多震层