安宁河–则木河–小江断裂带区域构造地震发生的时空概率分布估计

Estimation of Temporal and Spatial Probability Distribution of Tectonic Earthquake Occurrence in Anning He-Zemuhe-Xiaojiang Fault Zone

基于安宁河–则木河–小江断裂带1983年7月15日~2023年12月31日Ms3.0及以上地震目录数据,按震级分组并创建发震时刻间隔序列,根据有感地震、中弱震和强震的不同,将数据划分为3.0级及以上、4.5级及以上和6.0级及以上三组,运用指示克里金法,在时间和空间两个维度上,通过分组拟合的方法,构建了各阈值组的半变异函数模型,并利用模型进行发震概率估计。将指示克里金时间与空间分布估计结果做乘积,得到时空概率估计,有以下几点结论:(1) 3.0级阈值组模型对于未来发震的时空概率估计结果为:2025年1月30日,在石棉县–冕宁县–宁南县–巧家县一带发生大于3.0级地震的概率最大,为0.822,其前后50天概率大于0.804;(2) 4.5级阈值组模型对于未来发震的估计结果为:2024年1月15日,在陆良县–曲靖市、九龙县–石棉县、华坪县–宁蒗彝族自治县一带发生大于4.5级地震的概率最大,为0.63,其前后17天概率大于0.616;(3) 6.0级阈值组模型对于未来发震时间未能做出有效估计,但给出了6.0级及以上地震高概率发震区域为九龙县、曲靖市、寻甸回族彝族自治县一带。这一分析结果可以为地震活动研究提供科学的依据,其分析方法和探索发震规律过程有利于解决地震安全性分析中待解决的科学问题。Based on the earthquake catalog data (Ms 3.0 and above) from July 15, 1983, to December 31, 2023, for the Anninghe-Zemuhe-Xiaojiang fault zone, earthquake events were grouped by magnitude, and an interval sequence of seismic occurrence times was created. The data were divided into three groups according to the magnitude thresholds for perceptible earthquakes, moderate to weak earthquakes, and strong earthquakes: Ms 3.0 and above, Ms 4.5 and above, and Ms 6.0 and above. Using indicator kriging, a variogram model was constructed for each threshold group by fitting the data in both temporal and spatial dimensions. The models were then used to estimate the probability of earthquake occurrence. The temporal and spatial probability estimates were combined to produce spatiotemporal probability estimations. The key findings are as follows: (1) For the Ms 3.0 threshold group, the highest probability of an earthquake larger than Ms 3.0 occurring by January 30, 2025, is 0.822 in the area of Shimian-Mianyang-Ningnan-Qiaojia, with a probability greater than 0.804 within a 50-day window. (2) For the Ms 4.5 threshold group, the highest probability of an earthquake larger than Ms 4.5 occurring by January 15, 2024, is 0.63 in the areas of Luliang-Qujing, Jiulong-Shimian, and Huaping-Ninglang, with a probability greater than 0.616 within a 17-day window. (3) For the Ms 6.0 threshold group, no effective time prediction was made, but the high-probability regions for an earthquake of Ms 6.0 or above were identified in the Jiulong, Qujing, and Xundian Hui and Yi Autonomous County areas. These results provide a scientific basis for earthquake activity research, and the analytical methods used to explore seismic patterns may help address unresolved issues in earthquake safety analysis.