Earth's moon looks rather dead and inactive. But in fact, moonquakes, or "earthquakes" on the moon, keep things just a bit shook up. Quakes on the moon are less common and less intense than those that shake Earth.
According to USGS scientists, moonquakes seem to be related to tidal stresses associated with the varying distance between the Earth and moon. Moonquakes also tend to occur at great depths, about midway between the lunar surface and its center