• Relocations of 1994 Northridge and 1971 San Fernando earthquakes using a 3-D velocity inversion. Note that the San Fernando aftershocks appear to reach the surface in the region where ground rupture was observed. In contrast, the Northridge aftershocks are cut-off by the San Fernando fault at depths of 5 to 8 km. The north-dipping San Fernando fault may have prevented the south-dipping Northridge rupture from reaching the surface. (Geophys. Res. Letters, May 1, 1995)