Scientists studying the magnitude 7.0 earthquake that struck Haiti earlier this year warn that it was caused by a previously unknown fault in the Earth's crust.
Purdue University professor Eric Calais presented his team's findings this week at a conference of geophysicists in Brazil.
He said the newly discovered fault could put Haiti at risk for more earthquakes, but that scientists will need to do more research to assess the danger.
Earthquakes happen along faults, areas where the massive slabs of rock that form the Earth's outer layer meet or overlap. When the slabs slip or collide, the ground shakes.
Scientists originally blamed the Haiti quake on movement along the well-known "Enriquillo" fault. But Calais' team found a previously unknown fault was responsible because of the way in which the ground moved.
They say the newly-discovered fault could be connected to a larger system of faults that have never been mapped.
Haiti is still struggling to recover from the January 12 earthquake that killed an estimated 230,000 people, left 1.5 million homeless, and caused $7 billion in damage.