TOPOVEL - A FORTRAN PROGRAM FOR TOMOGRAPHIC INVERSION OF POROSITY ANDVELOCITY STRUCTURE IN THE SUBSURFACE

With increasing demand for high-resolution underground imaging, crossh ole tomography has become an important geophysical remote-sensing meth od. In a typical crosshole tomography experiment. sources and receiver s are placed in two parallel boreholes and first-arrival travel-time d ata are collected between each source and receiver. Collected travel-t ime data are used to invert the compressional or shear-wave velocity s tructure between the boreholes. TOPOVEL, a FORTRAN program, is present ed for the inversion of 2-D compressional-wave velocity and porosity s tructures between two boreholes, Potential applications of TOPOVEL inc lude foundation and geotechnical engineering, environmental sciences, hydrogeology, and exploration geophysics.