Moonquakes are causing the moon to shrink over time

Mindy Sparks
May 14, 2019

The moon is shrinking - much like the way a grape shrivels into a raisin - and that may be causing it to have "moonquakes," according to NASA. Scientists know the Moon is too cold and still to have plate tectonics, like Earth, which keeps our whole crust sliding around in giant, continent-sized pieces.

As the moon's interior cools, it shrinks, which causes its hard surface to crack and form fault lines, according to research sponsored by NASA. Unlike the flexible skin of a grape when it shrinks into a raisin, the moon's brittle crust breaks. This breakage results in thrust faults, where one section of crust is pushed up over an adjacent section.

These fault scarps resemble small stair-step shaped cliffs when seen from the lunar surface, typically tens of yards (meters) high and extending for a few miles (several kilometers).

The increased funding request, announced by President Donald Trump on Twitter, comes almost two months after Vice President Mike Pence declared the objective of shortening by four years NASA's timeline for putting astronauts back on the moon for the first time since 1972.

On Dec. 12, 1972, Gene Cernan parked his moon buggy in a valley named Taurus-Littrow, where a slumping escarpment - nicknamed the "Lee-Lincoln scarp" - was observed on a hill in the distance, Scientific American reported. And as it shrinks, the moon actively produces moonquakes along the faults.

Magnitude 5 moonquakes are causing landslides on the Moon, Nasa researchers say.

US astronauts placed seismometers on the lunar surface during the Apollo 11, 12, 14, 15 and 16 missions, recording 28 shallow quakes up to nearly 5 magnitude, which is moderate strength. They developed an algorithm that enabled them to get a more accurate location for the epicenters of each quake. These tracks are evidence of a recent quake because they should be erased relatively quickly, in geologic time scales, by the constant rain of micrometeoroid impacts on the Moon.

This means that the Apollo seismometers recorded the moon shrinking, the researchers said.

These incredible findings were published today (May 13) in the journal Nature Geosciences.

Six out of the eight tectonically active moonquakes occurred when the Moon was at or close to its apogee, the point where it's most distant from Earth and where the diurnal and recession stresses create the most compression near the tidal axis. "These widely distributed stations made the Apollo network an ideal candidate for using sparse seismic network algorithms used on Earth where there aren't a lot of stations". For the past 10 years, the LRO has been taking pictures of the moon's surface, and scientists would like to compare photos of specific fault regions from different periods to search for recent moonquake activity evidence.

John Keller of NASA's Goddard Space Flight Center said: "It's really remarkable to see how data from almost 50 years ago and from the LRO mission has been combined to advance our understanding of the Moon while suggesting where future missions intent on studying the Moon's interior processes should go". The agency will establish sustainable missions by 2028, then we'll take what we learn on the Moon, and go to Mars.

Other reports by Iphone Fresh

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