Finite Difference Modelling for Tunnel Seismology

P039 FINITE DIFFERENCE MODELLING FOR TUNNEL SEISMOLOGY Summary 1 G. KNEIB AND A. LEYKAM Tunnelseis Friedleweg 25 79771 Klettgau Germany The diagonal differencing algorithm which takes spatial derivatives along the diagonals of the finite difference grid is well suited to solve the elastodynamic equations for tunnel seismic modelling because it is accurate and stable at discontinuities of the elastic medium. Spatial high-order finite difference operators increase accuracy and efficiency of the algorithm except at steps in the elastic properties where two-point 2 nd order operators are the best choice. The resulting algorithm keeps memory requirements and computational effort on a