moonquakes


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moonquakes

Localized disturbances inside the Moon, detected by the Apollo seismic network. Rare but strong moonquakes occur 50–300 km below the surface, although they are much less intense than earthquakes by a factor of about 1000. Weaker but more numerous moonquakes occur at depths of 800–1000 km and are triggered at perigee by lunar tides. Seismic signals on the Moon are extended by scattering in the dry and porous lunar crust. Deep moonquakes provide information, through their arrival times, of the structure of the lunar interior: a 60 km crust on average, a mantle extending to a depth of 1100 km or more, and a central partly molten core roughly 500–600 km in radius.
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The intensity of Moonquakes, on the other hand, grew gradually as opposed to arriving in waves.
The Apollo 11 seismometer operated for only three weeks, but the four remaining recorded 28 shallow moonquakes --the type expected to be produced by these faults--from 1969-77.
Findings of the paper suggest that the moon may still be shrinking today and actively producing moonquakes along these thrust faults.
"Our analysis gives the first evidence that these faults are still active and likely producing moonquakes today as the Moon continues to gradually cool and shrink," said Thomas Watters, senior scientist in the Center for Earth and Planetary Studies at the Smithsonian's National Air and Space Museum in Washington.
You don't often get to see active tectonics anywhere but Earth, so it's very exciting to think these faults may still be producing moonquakes."
Apollo missions to the moon brought seismometers to the lunar surface as well, detecting thousands of moonquakes and meteorite impacts.
The astronauts deployed long-lived instruments on the lunar surface, including seismometers that measured moonquakes. Study of these quakes showed that the Moon has a crust, a mantle, and possibly even a small metallic core.
(51) Nakamura's (2003) reanalysis of old Apollo seismic data has revised sharply upward the actual number of deep moonquakes positively identified by a factor of five.
A theory offered by the team to explain the puzzle is that "moonquakes"-seismic shaking brought on by meteorite impacts or gravitational tides from Earth-may have caused Shackleton's walls to slough off older, darker soil, revealing newer, brighter soil underneath.
The satellite orbiter would then act as a telecommunications station between the surface network and the Earth, relaying information to the Earth during the penetrators' one year life on the strength and frequency of moonquakes and the thickness of the crust and core.
There are already plans to send a probe to study rocks on the Moon and another called MoonLite to fire missiles into the surface to study the resulting "moonquakes".
The darts, shot into craters and penetrating to a depth of two metres, would send back information about possible "moonquakes" and the composition of the Moon's core.