Haiti Quake Increased Stress Along Fault

The destructive magnitude 7.0 earthquake that ruptured a 40‐kilometer segment of the Enriquillo fault 15 kilometers from Port au Prince, Haiti, on 12 January 2010 has dangerously increased the failure stress on an adjacent eastern segment of that fault, according to research presented on 3 May at the European Geosciences Union General Assembly in Vienna, Austria. Jian Lin, a senior scientist with the Geology and Geophysics Department at Woods Hole Oceanographic Institution (WHOI), in Massachusetts, explained that the Haiti quake brought the eastern segment about 2–5 bars closer to failure. With 1 bar equal to atmospheric pressure at sea level, a 2‐to5‐bar increase may not seem significant, Lin said. However, the fault has not ruptured for about 240 years, and it has built up about 1.5–2 meters of stress, at an estimated rate of 7–8 millimeters per year. An increase of just a few bars could act as a trigger, he said. “It's just like your car is on the edge. Now just give a kick and it's going to fall,” he told Eos .