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滇西南地区地处青藏高原东南边缘,是我国大陆构造活动强烈且强震频发地区之一.通过分析b值与地壳应力分布状态的负相关关系,采用最大似然法对该区进行b值空间扫描,并结合区域地震构造背景以及活动断裂特征,分析该区b值空间分布沿各断裂带的空间差异性,反映区内不同断裂带以及同一断裂带不同现今应力积累水平与活动习性的差异,从而反映出地震危险性的空间差异.研究结果表明:滇西南地区b值处于0.3~1.2之间,平均b值为0.576,δb值为0.046;区内断裂带与断裂带不同段落的b值分布极其不均匀,澜沧江断裂南段、怒江断裂带等断裂处于研究区低b值区域,目前处于相对较高的应力状态,未来发生强震的可能性较大;而哀牢山断裂带、龙陵-瑞丽断裂带的西段和东段等断裂处于研究区高b值区域,目前处于相对较低的应力积累水平,未来以小震活动为主.该研究方法和结论可供工程场地地震安全性评价和地震活动性中长期预测研究时参考.
Southwest Yunnan Province is located in the southeastern margin of the Qinghai-Tibet Plateau, which is one of the strong tectonic activities and frequent strong earthquakes in China. By analyzing the negative correlation between the b value and the crustal stress distribution, the b value Spatial scanning and combining with the regional tectonic setting and active fault features, the spatial distribution of b value in this area is analyzed to reveal the difference between current stress accumulation level and active habit of different fault zones in the same zone and the same fault zone , Which reflects the spatial difference of seismic hazard.The results show that the b value of southwestern Yunnan is between 0.3 and 1.2, the average b value is 0.576, and the δb value is 0.046.The b value of different sections of the fault zone and fault zone The distribution is extremely uneven. The faults such as the southern section of the Lancangjiang River fault and the Nujiang fault zone are located in the low b value area of the study area and are at relatively high stress state. Therefore, the possibility of strong earthquakes in the future is greater. However, the Ailaoshan fault zone, The faults such as the western segment and the eastern segment of the Taili-Ruili fault zone are located in the high b value area of the study area and are currently at relatively low levels of stress accumulation and are mainly characterized by small earthquakes in the future. Reference for seismic safety evaluation of seismic activity and long-term forecast for the engineering study on the site.