Fan-delta uplift and mountain subsidence during the Haiti 2010 earthquake

Abstract

The relative motion between the Caribbean and North American plates is accommodated by several active faults around Hispaniola Island1, 2, 3. The Enriquillo–Plantain Garden fault in southern Haiti is one of these structures2, 4. Strain equivalent to a magnitude 7.2 earthquake is estimated to have accumulated along this fault since its last significant activity4. The Haiti earthquake of 12 January 2010 was initially reported to have occurred along this fault5, 6, but more recent studies proposed slips on previously unrecognized, neighbouring faults5, 7, 8. Here we use interferometric synthetic aperture radar data to show that surface deformation caused by the earthquake does not correspond to the present topography. Alluvial fan deltas were uplifted on the north side of the Enriquillo–Plantain Garden fault, whereas mountains located on the south side of the fault subsided, implying that faults other than the Enriquillo–Plantain Garden fault were responsible for the deformation. To determine fault structure, we fit the satellite surface deformation data to a fault model. We show that slip occurred on a fault dipping northward at 42°, with large thrust components. The maximum displacement on the fault was about 4 m at 10–20 km depth, offshore from the Tiburon peninsula. We confirm that the earthquake ruptured a blind thrust fault and show that the fault could not be identified from large-scale present-day topography.