The numerical simulation of thesource development of the Tangshan earthquake

Ｔｈｅｎｕｍｅｒｉｃａｌｓｉｍｕｌａｔｉｏｎｏｆｔｈｅｓｏｕｒｃｅｄｅｖｅｌ┐ｏｐｍｅｎｔｏｆｔｈｅＴａｎｇｓｈａｎｅａｒｔｈｑｕａｋｅＺＨＩ－ＲＥＮＮＩＵ（牛志仁）ＤＡＮＧ－ＭＩＮＣＨＥＮ（陈党民）ＢＩＮＧ－ＱＩＡＮＬＩ（李炳乾）Ｓｅｉｓｍｏｌｏ...

The numerical simulation of the source development of the Tangshan earthquake

According to the precursory data of the 1976 Tangshan earthquake (M = 7.8), and combining with the research results of rock fracture, seismic source, tectonics, seismic precursors, dynamic condition and crust structure, the seismogenic process of Tangshan earthquake has been numerically simulated by using the model of water-saturated porous medium with a rhombic hard inclusion. First, a system of seismogenic dynamics equations of solid-liquid two-phase medium has been set up under considering rock inelastic dilation, strain-softening and pore-water permeation. Then, the finite difference method to solve the equation system in incremental form has been presented. Finally, the seismogenic process of Tangshan earthquake and the temporal-spatial characteristics of its precursors have been numerically simulated when the hard inclusion includes a soft fault belt. The numerically simulating result shows that the development of Tangshan earthquake mainly undergoes following processes: elastic accumulation, early inelastic cubic dilation, accelerative softening (failure and creep) of fault first time, inelastic dilation twice in Tianjin—Ninghe area, accelerative softening of fault twice and instability. Corresponding to the fault accelerative softening, elastic recovery and inelastic dilation twice in some parts of seismogenic medium. By comparing with the data of precursory observation, ones can find the preceding simulating result explains the varied characters of practical data better. Meanwhile, the numerical simulation further displays the temporal-spatial change law and complex patterns of the field of Tangshan earthquake development as well. It makes a base study for the physical mechanism of change of the seismic precursory field. This subject is supported by the key project during the “8-th Five-year Plan” from the State Science and Technology Commission of China.