关于地壳中存在大规模虚空区的问题

AN APPROACH TO EXISTENCE OF LARGE SCALE GEO-VACUUM ZONES IN EARTH'S CRUST

地壳中存在大规模的虚空区。几乎所有破坏性的大地震都造成了大规模的地面下沉,正是因为虚空区的存在才使这种下沉成为可能;震碛岩的C单元则是这种地面沉陷现象的地质记录。虚空区的基本特点是其内部的实际垂向压力小于静压力。构造运动导致的这种垂向压力与周围压力之差,将使虚空区的岩石发生扩容。科拉半岛上超深钻探发现大量含自由水的裂隙带,证实了地壳中虚空区的存在。一般地说,可以通过探查地壳中的低速层来发现和研究虚空区。

There might exist large scale geo-vacuum zones in the earth＇s crust. Almost all destructive great earthquakes in China during history resulted in significantly extensive subsidence that could only reasonably be attributed to the existence of geo-vacuum zones in the crust. A geo-vacuum zone was basically characterized to be under a situation of lower vertical pressure than the theoretic hydrostatic pressure at the depth. Such vertical pressure decrease was induced by tectonic movements and might produce dilatancy of the rocks. Discoveries in the super-deep drilling well in the Kola Peninsula further confirmed the existence of such phenomena. Generally speaking, such geo-vacuum zones could be located and studied by investigating low velocity zones in the crust and synthesizing the data of geophysical survey. Geological evidence and implications, such as stratigraphic records of earthquake, lithological evidence and implication of fissure in oil-gas exploration, were discussed in the paper. In addition, the mechanism of geo-vacuum zone＇s formation was briefly discussed in the paper.