APOD 1.7

Moonquakes Suprisingly Common (Oct. 10, 2010)

This picture shows Buzz Aldrin standing on the moon next to a lunar seismometer. Apparently moonquakes, which are similar to earthquakes, are very common on the moon. Over the five years from 1972-1977, there have been a recorded 28 moonquakes. There are typically four types of moonquakes: deep moonquakes, vibrations, thermal quakes, and shallow moonquakes. The deep moonquakes occur 700 km below the surface and are probably caused by tides. The vibrations are caused by the impacts from meteorites. The thermal quakes are caused when the crust expands because of the sun after two weeks of deep freeze lunar nights. Shallow moonquakes are usually 20-30 km below the surface. I thought that the first 3 were major ones, but it turns out that the shallow moonquakes are actually more serious than the previous 3. This is because the shallow moonquakes tend to last longer. They describe it like hitting a tuning fork. It will keep going on and on. It usually lasts for 10 min compared to the half a minute quakes that we feel on Earth. It is amazing that the quakes can last this long. I wasn't even aware that the moon had quakes. From the typical pictures we see of the moon, the moon looks so peaceful and quiet. I was suprised to know that the moon had some similar quakes as we do on Earth and how intense they can really be. I have been through earthquakes that have lasted several seconds, I can't imagine enduring a 10 min one.