The Moon is shrinking: its circumference has shrunk by more than 45 meters as a result of the gradual cooling of the core over the last hundreds of millions of years.
The confirmation comes from a study led by the American Smithsonian Institute and published in the journal The Planetary Science Journal, which demonstrated that, a bit like grapes shrivel and turn into raisins, the Earth's satellite has also developed folds and faults in its places where parts of the moon's crust collide against each other.
This phenomenon, however, causes earthquakes and landslides which constitute a danger for future human missions: the continuous shrinkage, in fact, has led to significant surface deformations even in the South Pole region, where NASA's Artemis III mission is expected to land.
Researchers led by Thomas Watters have linked a group of faults located in the southern polar region of the Moon, recently identified by NASA's Lunar Reconnaissance Orbiter, to one of the most powerful earthquakes recorded over 50 years ago by the seismometers positioned during the Apollo missions.
Just as on Earth, seismic events on our satellite can be strong enough to damage buildings, equipment and man-made structures but, instead of lasting just a few seconds or minutes, they can last for hours.
Just like the one under study, which reached magnitude 5.0 and lasted an entire afternoon.
This means that lunar earthquakes can devastate future human settlements.
“Our models suggest that shallow earthquakes capable of producing strong ground shaking are possible,” Watters says.
“The global distribution of new faults, the possibility that they are active and the risk that they form other faults following the ongoing global contraction, are factors that should be taken into consideration – concludes the researcher – when planning the position and stability of the future permanent outposts on the Moon."
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