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研究区域界面和速度的两步反演计算方法．三维界面采用分段非完全多项式描述，三维速度的重建采用泛函空间的最小二乘原理．计算采用两步进行：第１步反演三维界面形态；第２步将剩余走时残差按加权分配的方式进行三维速度反演．处理了唐山滦县震区地震测深资料，获得了唐山震区深部三维构造形态及唐山、滦县震区三维地壳速度分布．结果表明：唐山震区深部三维构造总体为北东走向，北东向的丰台—野鸡坨断裂与北东向的唐山断裂所夹的构造为莫霍界面隆起区．该区中下地壳三维速度结构沿北东向的唐山断裂存在明显低速异常带，其位置与唐山地震活动带的位置相一致．沙河驿附近较大的低速异常块体对应于较密集的地震分布．该区域存在一条北西向的高速异常带，可能是一条隐伏深断裂．唐山７．８级地震震中区下地壳为北东向的低速异常带与北西向的高速异常带相交处．这两组构造对控制唐山７．８级地震的孕育和发生起了重要作用．
A two-step inversion method to study the interface and velocity of the area. The three-dimensional interface is described by subsection non-complete polynomial, and the reconstruction of 3D velocity adopts the least squares principle of functional space. The calculation is carried out in two steps: the first step is to invert the three-dimensional interface morphology; the second step is to perform the three-dimensional velocity inversion of the remaining travel time residual by weighted distribution. The seismic sounding data of Luanxian earthquake area in Tangshan have been processed and the deep three-dimensional tectonic shape of Tangshan earthquake area and the three-dimensional crustal velocity distribution in Tangshan and Luanxian areas have been obtained. The results show that the deep three-dimensional structure of the Tangshan earthquake area is generally northeastward, and the northeastern Fengtai-Yeji Tuo fracture and the NE-trending Tangshan fault have the Moho intercalation uplift. There is a clear low-velocity anomalous zone along the NE-trending Tangshan fault in the three-dimensional velocity structure of the middle and lower crust in this area, which is consistent with the location of Tangshan seismic belt. Larger low velocity anomaly blocks near Shaheyi Station correspond to more intensive seismic distribution. There is a NW-trending anomalous zone in this area, which may be a deep buried fault. The lower crust in the epicenter area of the Ms = 7.8 Tangshan earthquake is the intersection of the NE-trending low-velocity anomalous zone and the NW-trending high-velocity anomalous zone. These two structures play an important role in controlling the occurrence and occurrence of the MS7.8 Tangshan earthquake.