Unlike the devastating 2010 Haiti earthquake, an eighteenth-century precursor event ruptured the surface near the main fault system implicated in the earthquake, reports a study published online this week in Nature Geoscience. These observations suggest that the fault system may still pose a significant seismic risk to the region around Port-au-Prince. This paper is published as part of Nature Geoscience’s special issue on the Haiti earthquake.

Carol Prentice and colleagues used remote sensing and field investigations to map any offset of the land surface associated with the Haiti earthquake of 12 January 2010, or a precursor event. They documented nine streams whose beds had been offset, probably by only one of the two large earthquakes that occurred on the same fault system in 1751 and 1770, respectively, implying that these events ruptured the land surface. However, the devastating 2010 quake did not leave a surface trace.

The findings suggest that not all the strain accumulated over the past two-and-a-half centuries or so was released during the event in January.