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- The seismometers left on the moon by the Apollo missions recorded 28 moonquakes between 1969 and 1977.
- At least eight are related to thrust faults that form when the moon narrows.
A new study indicates that the moon is slowly narrowing over time, creating wrinkles in the crust that could trigger moonshakes.
A NASA-led team of researchers used a new algorithm to reanalyze seismometer data placed on the moon during several Apollo missions from 1969 to 1977. She compared these data to more than 12,000 photos taken by Lunar Reconnaissance Orbiter (LRO) from NASA since. 2009 and determined that the moon measured 164 feet "leaner" than in the early 1970s.
According to the study published this week in Nature Geosciences, the inside of the moon shrinks like a grape while it cools, creating wrinkles on the moon's surface, called flawed flaws.. Unlike the soft skin of a grape that shrinks into a grape, the surface of the moon is brittle and it breaks and cracks when it contracts. The thrust faults that appear on the surface of the moon are like cliffs or escarpments in the form of stairs and are generally several meters high and several kilometers long.
The LRO has photographed more than 3,500 of these scarves on the moon since 2009.
Seismometers recorded 28 earthquakes ranging from 2 to 5 on the Richter scale between 1969 and 1977. The algorithm then allowed scientists to better understand the epicentres of earthquakes. They found that eight of these shallow earthquakes were located within 30 km of visible thrust faults in LRO lunar imagery.
Two instruments placed on the Moon in July 1969 by Apollo 11 astronauts: a seismometer (in the foreground) and a laser telemetry retroreflector designed by a team led by the University of Maryland.
(University of Maryland)
The researchers also determined that six of the eight earthquakes related to thrust faults occurred when the moon was at its apogee or greater distance from Earth, where "the additional tidal stress due to Earth's gravity caused a peak of total stress on the moon crust. "
"We think it's very likely that these eight earthquakes were caused by errors that slipped as stress accumulated. when the lunar crust was squeezed by global contraction and tidal forces, indicating that the Apollo seismometers recorded the decrease of the Moon and that the Moon is still active ", Thomas Watters, Senior Scientist of Earth and planet studies at the Smithsonian's National Air Space Museum in Washington, said in a press release.
The research has led to more questions about what is happening as the moon ages. While seismometers were removed in 1977, images capturing landslides and fallen rocks suggest that moonshells continue to occur. Future research can also help scientists understand what is happening to other celestial bodies, such as the planet Mercury, which is also shrinking and has thousands of flawed faults.
"For me, these results underscore the need to return to the moon,Said Nicholas Schmerr, co-author, assistant professor of geology at the University of Maryland. "We learned a lot from the Apollo missions, but they only scratched the surface. With a larger network of modern seismometers, we could make enormous progress in our understanding of the geology of the moon. This gives very promising fruits for science during a future mission on the Moon. "
"The establishment of a new network of seismometers on the lunar surface should be a priority for human exploration of the moon, both to learn more about the interior of the moon and to determine the magnitude of the moonquakes on the risks, "Renee Weber, co-author of the study and planetary seismologist at NASA's Marshall Space Flight Center, said in a statement.
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