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.