The devastating Haiti earthquake on 12 January 2010 involved slip on numerous faults, but resulted in very little deformation of the ground surface, according to a study published online this week in Nature Geoscience. Initially the Haiti earthquake was thought to be the consequence of movement along a single fault, which accommodates the motion between the Caribbean and North American plates. This paper is one of the first two to be published this month as part of Nature Geoscience’s special issue on the Haiti earthquake.

Gavin Hayes and colleagues used a combination of seismological observations, geologic field data and satellite geodetic measurements to analyse warping of the ground caused during the earthquake. By modelling the patterns of surface deformation, they were able to assess which fault was responsible. Their results showed that the earthquake may not have been caused by the simple rupture of a single fault, but instead may have involved a complex series of faults. The pattern of surface deformation was caused by some movement on a previously unknown, subsurface thrust fault, named the Leogane fault. The thrust fault caused older rocks to be pushed up over younger ones, but did not rupture the surface.