Velocity structure for all of our simulations. The true model, shown on the left, is an approximate subduction zone structure. The model for time reversed wavefield calculations, shown on the right, is produced by using a Guassian filter to smooth the true model. There are 129 stations uniformly distributed in a horizontal line across the surface of the domain at a spacing of approximately 270 m. Source locations are shown for the earthquakes used in all of our tests: Pink pentagons show the locations of six sources dipping +75°, blue stars show the locations of six sources dipping −75° and yellow stars show the locations of eight isotropic sources and eight sources dipping +45°.