New research on friction between faults could aid in predicting the world’s most powerful earthquakes. Researchers discovered that fault surfaces bond together, or heal, after an earthquake. A fault that is slow to heal is more likely to move harmlessly, while one that heals quickly is more likely to stick until it breaks in a large, damaging earthquake. Tests allowed them to calculate a slow, harmless type of tremor. The discovery alone won’t allow scientists to predict when the next big one will strike but it does give researchers a valuable new way to investigate the causes and potential for a large, damaging earthquake to happen, and guide efforts to monitor large faults like Cascadia in the Pacific Northwest.