基于局部一维模型与走时标定的区域 三维速度模型构建技术研究

构建区域介质三维速度模型并以之获得准确的区域震相走时， 是提高区域地震定位精度的重要手段之一. 为充分利用已有的一维模型、 GT事件、 地质资料等实现三维模型构建， 尝试基于目标区域内已有的部分局部一维模型， 通过克里金空间插值建立初始三维模型， 然后利用GT事件走时数据并参考其它地震地质资料对其不断进行修正， 使得其走时偏差图与GT事件走时偏差图一致， 进而获得能够提高区域地震定位精度的三维模型. 使用不同模型进行的地震定位实验表明， 以此方法建立的三维模型的定位偏差较初始模型减少约20%， 较好地起到了减小区域震相走时残差， 提高区域地震定位精度的作用. 

Construction of 3D velocity structure using local 1D model and travel-time calibration

Calculating accurate regional phase travel-times through regional 3D velocity models constructed is one of the important means to improve regional seismic event location accuracy. Using local 1D model, ground truth (GT) events and geological data, construction of 3D velocity model is carried out as follows: First, we construct an initial 3D velocity structure through Kriging method using some local 1D velocity models; then, modify it repeatedly by GT event travel-times and geological data until the minimum travel-time bias is reached; and finally, the modified 3D velocity model is obtained. Location testing is performed with different velocity models. It shows that the modified 3D velocity model can improve regional event location accuracy, and the bias of epicenters is decreased by about 20% statistically.