A STUDY OF THE EARTHQUAKE FAULTING PROCESS AND EARTHQUAKE PREDICTION IN THE LIGHT OF FRACTURE MECHANICS

The formulas of strain energy release rate and crack sliding displacement pro-pesed in fracture mechanics have been used in the study of earthquake faulting process. Then, by applying the magnitude-energy relation, logee=α1M+α2, the relations between the earthquake source parameters and the stress conditions in the crust, for strike-slip, dip-slip and circular disk-shaped shear faults were derived. The results are summarized in Table 2. For the case of strike-slip fault, they are as follows:(6) The expression for determining regional stress τ0, M0 =where M, magnitude of earthquake; L, W length and width of the fault; tj, seismic efficiency: To, regional shear stress; τy, yielding shear strength; fi, rigidity modulus; v, Poisson Ratio; D, average dislocation and M0, the seismic moment.The yielding strength under the stress condition prevailing in the crust, can be measured in the laboratory, therefore, by means of (6) or (1), the regional shear stress can be esyimated from earthquake data. It can be seen that a considerable difference exists between the relations mentioned above and the relations for the earthquake source parameters in current use. It is because, in the latter case, the initial and final stress condition of the fracture are only taken into consideration, whereas in the former case, the fracture process in the light of fracture mechanics has been dealt with.