基于阿里亚斯烈度估值的概率性地震危险性分析——以四川丹棱县及其周缘为例

以编制《中国地震动参数区划图》时所构建的地震潜在震源区模型和地震活动性模型为基本输入,在四川省丹棱县及其周缘地区开展基于阿里亚斯烈度的概率地震危险性分析,计算50年超越概率10%的阿里亚斯烈度(Arias Intensity,Ia)。结果表明:丹棱县及其周缘绝大部分地区的Ia值都在0.11m/s以上,部分地区在0.32m/s甚至0.54m/s以上,具有较高的地震诱发滑坡风险,应当加强人员密集区的地震诱发滑坡危险性评估。根据不同Ia预测方程计算得到的Ia分布有较大差异,因此在计算Ia时应考虑多个Ia预测方程,对最终结果进行加权平均,以减小Ia结果的不确定性。同时还发现Ia值与1.0s的谱加速度具有很好的相关性,这也印证了Ia和1.0s谱加速度与砂土液化的相关性。

Probabilistic Seismic Hazard Analysis Based on Arias Intensity: A Case Study in Danling County, Sichuan Province and Its Surrounding Area

Arias Intensity is a ground motion parameter that contains amplitudes, frequencies, and duration of ground motion. It is more reliable in some predictions of seismic damage than the parameters that only depend on the amplitude of ground motion. Scientists have shown that Arias Intensity has a strong correlation with landslides induced by earthquakes. This study presents a preliminary probabilistic seismic hazard assessment in terms of the Arias Intensity in Danling County, Sichuan Province using a seismic source model and the seismicity model established by the Seismic Ground Motion Parameters Zonation Map of China. The results show that the I_a value for most of Danling County and its surrounding area is above 0.11 m/s. Some parts of the area has a value of 0.32 m/s. Some even has more than 0.54 m/s, where a relatively high hazard of earthquake-induced landslides can be found. Hence, we should strengthen the risk assessment of earthquake-induced landslides in personnel concentration areas. An obvious difference is found in the calculation of the I_a distribution according to different I_a prediction equations. Therefore, we should consider more than one I_a prediction equation when calculating the I_a value. The weighted average of the final results is derived to reduce the uncertainty of the I_a value. We also find a strong correlation between I_a and spectral acceleration (t=1.0 s), which confirm the correlation between sand liquefaction and I_a.