About 14% of magnitude 6.7 or greater strike-slip earthquakes since 2000 have been supershear. That's 50% more than previously thought. Supershear earthquakes occur when a fault ruptures faster than seismic shear waves can travel through rock. The events were thought to be rare because scientists had mostly looked for them on land. The findings suggest that disaster planning assessments should include whether a fault is able to produce supershear quakes, which are potentially more destructive than other types.