High resolution seismic refraction method using surface and borehole data for site characterization of rocks

The authors have developed a new method for the analysis of seismic refraction data, which can handle both surface and borehole data simultaneously. The main features of the method we developed are as follows: (1) The algorithm of analysis is based on the tomographic reconstruction technique. and refraction data can be analyzed almost automatically after traveltime picking. (2) The method is applicable to both layered velocity structures and those showing a velocity gradient with depth. (3) In order to apply the seismic refraction technique to a site that has a more complex structure, the method can use the data obtained from sources and receivers on the surface, as well as those within boreholes simultaneously. Numerical and actual field examples have shown that the method can greatly improve the accuracy and the reliability of the seismic velocity models obtained by the seismic refraction method as compared to the conventional analysis methods. It can also shorten the data processing time drastically and reduce the survey cost. (C) 2001 Elsevier Science Ltd. All rights reserved.