Scientists have observed that the moon has started to shrink as its interior started to cool down. They have reported that the moon has become more than about 150 feet thinner than it was 100 million years ago.
The shrinking moon was compared to a grape that shrivels into a raisin. This means that the moon has obtained wrinkles as it decreases in size. However, unlike a grape, the moon's surface crust is very brittle. As the moon shrinks, the surface breaks down developing "thrust faults". This is seen when one area of the crust is pushed up over another.
As the interiors of the moon cooled down over the last several hundred million years, it causes the surface to wrinkle as it shrinks because the moon does not have tectonic plates like the ones that Earth has.
Thomas Watters stated that their analysis gives the first evidence that the faults are still active and are most likely causing moonquakes. Watters is a senior scientist from the Center of Earth and Planetary Studies at the Smithsonian's National Air and Space Museum located in Washington. The scientist added that the moon is continuing to gradually cool down and shrink. He pointed out that some of the quakes could reach a magnitude of five on the Richter scale which is fairly strong.
As of the moment, there are thousands of cliffs that are scattered across the surface of the moon. The average dimensions are about a few miles in length and tens of yards in height.
Since 2009, the arbiter has taken photos of over 3500 cliffs on the moon. In 1972, Eugene Cernan and Harrison Schmitt, Apollo 17 astronauts, were able to ascend one of these cliffs by maneuvering the rover to zigzag over it. The cliff was named Lee-Lincoln fault scarp.
This process of cooling down and drinking has rendered the Moon to be 50 meters skinnier. It has also actively produced quakes along the faults found on the surface of the moon. Seismometers were placed on the Moon by the Apollo astronauts. Quake locations were pinpointed using an algorithm or mechanical program detected by a sparse seismic network.
This data from four seismometers were reanalyzed by scientists.
Between 1969 to 1977, 28 shallow moonquakes were recorded by the instruments placed on the lunar surface during the Apollo missions.
According to the algorithm used by the scientists, eight of the 28 shallow quakes occurred within the range of 30 kilometers of the faults visible in lunar images.
Watters explained that it is highly likely that the eight quakes were produced by faults slipping as stress builds up when the moon's crust is compressed by global contraction and tidal forces. This means that the moon is tectonically active.
