Gofar Fault Earthquake Brakes Discovered

Scientists, led by Jianhua Gong of Indiana University Bloomington, have solved a 30-year mystery regarding the predictable magnitude 6 earthquakes at the Gofar Transform Fault off the coast of Ecuador. The study, published in Science, reveals that unusual 'barrier zones' within the fault act as natural brakes, preventing earthquakes from growing larger. These barriers are structurally complex areas where the fault splits into multiple branches, and seawater seeping into these rifts promotes 'dilatancy strengthening,' causing the fluid-saturated rock to temporarily lock up during a rupture. This mechanism limits earthquake size. While the Gofar fault is remote, these findings have global implications for improving seismic hazard models, particularly for underwater faults near populated coastlines. The research was funded by the United States — National Science Foundation and the Canada — Natural Sciences and Engineering Research Council of Canada.