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2013年12月16日三峡库区巴东发生Ms5.1地震.根据eigen-6c2模型研究了巴东地区的8-638阶卫星重力异常,结果表明:该地区场源深度为10km的地壳为局部重力低异常,反映了该处物质密度较周围偏低,形成低密度层.同时,研究了该地区速度结构剖面,结果表明:巴东地区地壳5~9km及10~15km深处存在上下两个低速层,上部低速层与水库渗水有关,下部低速层与地幔热流体的上涌有关.低密度层和低速层的确定为韧性流变层的存在提供了证据.巴东地震是地壳深部能量的长期集聚与突发释放,属构造地震.然而,库水下渗引起的上部低速异常降低了断层活动的阈值,震前库水载荷的变化对此次巴东地震的发生起到了触发作用.通过对比次声波和地震波,我们得出次声波仪记录到的异常信号为本地次声波.
The Ms5.1 earthquake occurred in Badong, the Three Gorges reservoir area on December 16, 2013. According to the eigen-6c2 model, the 8-638-order satellite gravity anomaly in Badong region was studied. The results show that the crust with a source depth of 10 km is locally The low gravity anomalies reflect the lower density of the matter and the formation of a low density layer.At the same time, the velocity structure of the area is studied, and the results show that there are two upper and lower crusts 5 ~ 9km and 10 ~ 15km deep in Badong area The low velocity layer and the upper low velocity layer are related to water seepage in the reservoir, and the lower low velocity layer is related to the upwelling of the mantle hydrothermal fluid.The determination of low density layer and low velocity layer provides evidence for the existence of ductile rheological layer.The Badong Earthquake is the deep crustal energy Long-term accumulation and sudden release are tectonic earthquakes, however, the upper low-velocity anomalies caused by reservoir infiltration reduce the threshold of fault activity, and the change of reservoir water load before the earthquake has played a trigger role in the occurrence of this Badong earthquake Comparing the infrasound and seismic waves, we find that the infrasound signal recorded by the infrasonic instrument is the local infrasound.