The experimental investigation of micro-cracks nucleation in typical tectonics

he evolution and nucleation of microcracks in typical tectonics are investigated in the experiment of fracture of marble specimen. The change of state during nucleation of microcracks is observed. The controlling effect of tectonics on evolution of microcracks is analyzed by using thc damage mechanics theory. These characteristics can be analogized to kilometer meters as the first effect of earthquake precursors. These studies may be helpful to interpret-the foreshock or general foreshock in the moderate or short stage before strong earthquakes. The other physical precursors are second or third effect. The local density of microcracks increasing abruptly may be helpful to interpret the phenomenon that part precursor records appear catastrophic jump. The part out of nucleation where some microcracks heal and the density change reversibly may be helpful to interpret the phenomenon that some precursors records appear reverse change. The area difference of microcracks accumulation and evolution in different part of typital tectonics is studied. This difference may be helpful to interpret the characteristics (including the area) of earthquake preparation of diffcrent tectonics, and further to interpret the difference of the precursors beween plate edge and intraplate. These differences may be introduced by the scholars with different points of view as to discuss about the existence of precursors before earthquakes. However, when the precursor records are studied, one must notice the geology background in different areas.