TOMO3D - A New 3-D Joint Refraction and Reflection Travel-time Tomography Code for Active-source Seismic Data

TOMO3D is a code for three-dimensional refraction and reflection travel-time tomography of wide-angle seismic data that inverts for the velocity field and the geometry of a reflector. Ray tracing is performed by a hybrid method combining the graph and bending methods, and the inversion is iteratively solved using an LSQR algorithm. We present a series of benchmark tests with synthetic data for the forward and inverse problems, as well as other more complex tests comparing inversions with refraction travel times only (i.e. first arrivals) to others with refraction and reflection travel times. The combination of refraction and reflection data increases ray coverage and thus velocity resolution, while allowing the determination of major geological interfaces, and reducing the velocity-depth trade-off.