Over the last decade, scientists have established that as the inside of the Moon cooled, it shrivelled up a like a raisin. That left it riven with cliffs called “thrust faults”, marked all over its surface.
Now a new analysis, using data from Nasa missions, suggests that the Moon could still be shrinking today. As it does, it is experiencing moonquakes along those thrust faults, with the rock shaking at the cliffs.
Scientists compare the process to the way a grape will gradually wrinkle up, adding lines as it cools and shrinks. But unlike a grape’s skin, the crust around the Moon cannot stretch and is instead brittle, making it break apart as the shrinking happens.
The faults form when the crust moves around, and one part of the crust is pushed up over another. They form unusual-looking cliffs that can be seen from the surface, standing tall and many miles long.
The new research was made possible by the creation of an algorithm that processed seismic data that was taken in the 1960s and 1970s. It helped shed new light on those moonquakes, including allowing for a better understanding of where they are actually coming from.
Once that location data was generated, it could be laid on top of the images of the thrust faults that were taken from a 2010 study that used pictures from Nasa’s Lunar Reconnaissance Orbiter.
Comparing the two, they found that at least eight of the rumbles were coming from movement of plates beneath the Moon’s surface, not from asteroid impacts or other explanations. That helped confirm that the Moon is still experiencing true tectonic activity, according to the new paper published in Nature Geoscience.
The instruments left by Apollo astronauts in the past finished their work in 1977. But scientists think this shaking and shrinking is still happening to this day, with images seeming to show evidence of recent movement, such as boulders and landslides that appear to have recently fallen over.
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SOURCE: The Independent, Andrew Griffin