The first thing to know about moonquakes is this: They last forever. While most earthquakes are over in under a minute, moonquakes can last for an afternoon. In the 1970s, at least one 5.5-magnitude moonquake shook the lunar surface at full force for more than 10 minutes straight, then tapered off gradually over the course of several hours.
“The moon was ringing like a bell,” Clive Neal, a geological sciences professor at Notre Dame, told NASA about the Apollo-era lunar seismic data he and his colleagues examined. A strong moonquake would be enough to devastate a hypothetical human settlement—breaching a moon base’s seal and causing a catastrophic loss of oxygen—which is part of why scientists became interested in studying the phenomenon in the first place.