Study And Application Of Time-dependent Seismic Hazard Zonation

Seismic zonation has vital importance to earthquake disasters comprehensive prevention, which includes land use planning, seismic fortification and emergency preparedness. Emergency preparedness considers seismic hazard in near future, which needs time-dependent seismic zonation.Seismic zonation is related to seismic hazard assessment. Seismic hazard assessment is a main part of Engineering Seismology, and has important guiding significance to the implementation of damage prevention work. Seismic hazard assessment is devided into deterministic method and probabilistic method. Troditional probabilistic seismic hazard assessment (PSHA) assumes earthquake accurence obeys Poisson distribution, in which probabilities of every level of magnitude obey Gutenberg-Richter (G-R) Magnitude-frequency relationship. The earthquake probability in this model does not change with time, which is called time-independent model. From Cornell (1968) raised PSHA method, researchers were trying to improve the Poisson model, and raised time-dependent seismic zonation methods. Time-dependent seismic zonation can give the seismic hazard result in near future in one area, which can give indication to the areas with upcoming major earthquakes, and reference to emergency preparedness.Time-dependent seismic zonation has two aspects of defferences with traditional seismic /onation. First, timp-dependent seismicity model considers two kinds of seismicity models the quasi-periodicity of major earthquake model and stress transfer and trigger model. Second,3-D near fault ground motion prediction model is considered in time-dependent source model. This dissertation systematically researched the foundation of the two time-dependent model and near fault ground motion prediction model, and founded time-dependent seismic zonation model.The application of time-dependent zonation model into seismic zonation work of China in areas such as Bayan Har Block, North-South Seismic Zone and Taiyuan and surrounding areas has important practical significance. This dissertation reevaluates seismic hazard zonation in those areas, showed the distribution of probability of exceedance with certain ground motion parameters in the next 5,10 and 15 years. We compared our results with the calculation by time-independent model, and then showed some areas with high seismic hazard over the next 5,10 and 15 years.Based on the researches above, this dissertation achieved some progress and advances:(1) This dissertation founded two kinds of time-dependent seismicity models based on the quasi-periodicity of major earthquake model and stress transfer and trigger model, provided technical support to seismic risk assessment and targeted emergency preparedness, and promoted the development of accurate disaster prevention technologies.(2) This dissertation systematically researched two kinds of time-dependent PSHA methods, and raised the time-dependent PSHA method with Coulomb stress model and BPT model.(3) This dissertation considered near fault effect of major earthquake, and introduced 3-D near fault ground motion prediction model into time-dependent seismic zonation model.(4) This dissertation compiled seismic hazard calculation program based on time-dependent PSHA.(5) This dissertation applied time-dependent seismic hazard zonation into some areas of China, drew time-dependent seismic zonation maps of Bayan Har Block, North-South Seismic Zone and Taiyuan and surrounding areas.This paper extended the application of seismic zoning in the earthquake disaster comprehensive prevention, and explored the method to enhance the scientific nature of emergency preparedness for earthquake catastrophe.