深源地震机理的新认识──反向裂隙断层作用

A NEW MECHANISM OF DEEP-FOCUS EARTHQUAKES:ANTICRACK FAULTING

高温高压实验究表明，地幔矿物相交与深源地震有着密切的关系。在具有放热效应的橄榄石一尖晶石相变过程中形成的反向裂隙（ａｎｔｉｃｒａｃｈ）是诱发深源地震的主要原因；而发生在下地幔的相变作用（例如钛铁矿－钙钛矿相变）因其具有吸热效应的特征，不形成反向裂隙，从而导致深源地震终止于下地幔顶界。

The results of high temperature and high pressure experimental research indicate that the occurrence of deep-focus earthquakes is closely related to the mantle phase transformation.Anticrack faulting during the exothermic phase transformation of olivine to spinel is considered the major cause for the development of deep-focus earthquakes.And the cause for the termination of deep-focus earthquakes at the top of lower mantle is that anticracks cannot be developed during the endothermic phase transformation in the lower mantle(such as ilmenite to perovskite phase transformation).As there is no anticrack formed,no shear instability is produced.