Fault identification for buried strike-slip earthquakes using InSAR: The 1994 and 2004 Al Hoceima, Morocco earthquakes

The 1994 M w 6.0 and 2004 M w 6.5 Al Hoceima earthquakes are the largest to have occurred in Morocco for 100 yr, and give valuable insight into the poorly understood tectonics of the area. Bodywave modelling indicates the earthquakes occurred on near-vertical, strike-slip faults with the nodal planes oriented NW-SE and NE-SW. Distinguishing between the primary fault plane and auxiliary planes, using either geodetic or seismic data, is difficult due to the spatial symmetry in deformation fields and radiation pattern of moderately sized, buried, strikeslip earthquakes. Preliminary studies, using aftershock locations and surface observations, have been unable to identify the orientation of the primary fault plane for either earthquake conclusively. We use radar interferometry and aftershock relocation of the earthquake sequence to resolve the ambiguity.