Here's a great link that talks about data from these seismometers: http://www.nasa.gov/exploration/home/15mar_moonquakes_prt.htm http://www.nasa.gov/exploration

Here's a great link that talks about data from these seismometers: http://www.nasa.gov/exploration/home/15mar_moonquakes_prt.htm http://www.nasa.gov/exploration/home/15mar_moonquakes_prt.ht... Some relevant quotes: 'There are at least four different kinds of moonquakes: (1) deep moonquakes about 700 km below the surface, probably caused by tides; (2) vibrations from the impact of meteorites; (3) thermal quakes caused by the expansion of the frigid crust when first illuminated by the morning sun after two weeks of deep-freeze lunar night; and (4) shallow moonquakes only 20 or 30 kilometers below the surface.' ... 'Furthermore, shallow moonquakes lasted a remarkably long time. Once they got going, all continued more than 10 minutes. "The moon was ringing like a bell," Neal says. 'On Earth, vibrations from quakes usually die away in only half a minute. The reason has to do with chemical weathering, Neal explains: "Water weakens stone, expanding the structure of different minerals. When energy propagates across such a compressible structure, it acts like a foam sponge--it deadens the vibrations." Even the biggest earthquakes stop shaking in less than 2 minutes. 'The moon, however, is dry, cool and mostly rigid, like a chunk of stone or iron. So moonquakes set it vibrating like a tuning fork. Even if a moonquake isn't intense, "it just keeps going and going," Neal says. And for a lunar habitat, that persistence could be more significant than a moonquake's magnitude.' ---------- Edit: Aha! I wonder if it was Werner Von Braun who first said the moon "rang like a bell." That was the search phrase I used to find the above. Here's a really cool article by him in Popular Science from 1970, talking specifically about the impact from Apollo 12's Lunar Module [2]. "The object of the deliberate crash was to see what the instrument would report to earth, and the result astounded scientists. The moon rang like a bell!" [1] http://www.nasa.gov/exploration/home/15mar_moonquakes_prt.htm http://www.nasa.gov/exploration/home/15mar_moonquakes_prt.ht... [2] http://books.google.com/books?id=VQEAAAAAMBAJ&lpg=PA62&ots=ocQn84yFer&pg=PA62#v=onepage&q&f=false http://books.google.com/books?id=VQEAAAAAMBAJ&lpg=PA62&#...