Probabilistic seismic hazard assessment using spatially smoothed seismicity in North China seismic zone

摘要

In this study, we use a spatially smoothed seismicity procedure for seismic hazard analysis in North China seismic zone by establishing four spatially smoothed seismicity models according to the seismic catalogs of North China and calculating peak ground acceleration (PGA) values with 10% probability of exceedance in 50years. The results show considerable differences between seismic hazards based on different models in certain areas, which is attributable to disparities in the seismicity levels of the four seismic models in those areas. In general, seismic hazard based on different models can be used as reference to evaluate uncertainty. In this paper, we also compare the mean PGA based on four spatially smoothed seismicity models with another PGA calculated using the zoning method based on surface seismic sources adopted for generating the Seismic Ground Motion Parameter Zonation Map of China, and find that the results of the two methods are largely similar, both of which can reflect the seismic hazard level of North China. However, there are differences at certain points, which are because the zoning approach adopts the same earthquake occurrence rate in the seismic source, while the spatially smoothed seismicity approach has different occurrence rates at different points. The discrepancies between the two can be attributed to differences in the principles adopted when potential seismic sources are classified. In particular, the PGA values of Beijing with 10% probability of exceedance in 50years is 177.0cm/s(2), 214.2cm/s(2), 252.8cm/s(2), and 187.5cm/s(2) in four spatial seismicity models, respectively. These PGA values are very important for evaluating the uncertainty of seismic hazard in Beijing. This study is an attempt to perform seismic hazard analysis using spatially smoothed seismicity models in China and recommends using this approach for areas where seismic sources are not clearly identified.