On 9 July 1998 an earthquake occurred NE of Faial Island (Azores, North Atlantic). The Harvard CMT solution points to a sub-vertical strike-slip event corresponding to the strikes N241E and N151E. Here, we use GPS data to estimate the coseismic displacements and to constrain the geometry of the earthquake source. GPS observations collected between 1993 and 1999 are processed to separate the interseismic and coseismic movements. Additionally, a displacement field is derived from a denser GPS network of 30 stations. We model the coseismic movements by a dislocation in a homogenous elastic half space. The data do not allow to infer the fault strike direction, which have helped to understand the relationships with the regional geodynamics. However, the models give consistent figures for the fault surface (≈40 km2), the coseismic slip (1 m) and the depth of the upper and lower edges of the fault plane (2 and 6 km).