Numerical source implementation in a 2D finite difference scheme for wave propagation

We describe how to implement seismic sources in a 2D staggered grid of a finite difference scheme of P-SV wave propagation. By comparison with analytical solutions in a homogeneous medium, we show that a very simple numerical description of sources in a second-order scheme provides good accuracy for radiated waves if one takes the elementary length where 2D stresses are applied as the grid step of the numerical scheme. The accuracy will depend on the grid step and the time step. The error is less than 10% and depends on the azimuth to the station.