An earthquake on the moon is called a moonquake. Unlike the ones that strike the earth, moonquakes happen less frequently and have smaller magnitudes than their counterparts on earth. While quakes on earth are caused by the movement of plates(plate tectonics), moonquakes are caused by totally different mechanisms.
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According to NASA, quakes can form due to four different mechanisms: meteoric impacts; thermal quakes caused by the expansion of the frigid crust by the suns' heat(280'C) for a period of two weeks and cooling during the lunar night; deep quakes about 700km below the surface caused probably by tides; and shallow moonquakes is not known. While the deep moonquakes are mild, the shallow quakes last for a long time -- as long as 10 minutes (earthquakes generally last for less than a minute or two).
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According to NASA, the dry, cool and rigid nature of the moon could be the reason for shallow quakes to last for a long period even if the quake is a lid one."Moonquakes set the moon to vibrate like a tuning fork," NASA notes.
credit: third party image reference
The presence of water on earth, on the other hand, dampens quakes. The rocks are also weathered and that makes the vibrations weaken with time and distance. Between 1972 and 1977, the Apollo seismic network recorded 28 shallow moonquakes. A few quakes had a magnitude of 5.5.
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