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“As the interior cools, the moon is shrinking. Over the past few hundred million years, the moon has shrunk by about 150 feet.” NASA recently released a latest study showing that as the moon cools and shrinks, strong moonquakes will occur.

The contraction of the moon creates moonquakes

The article states that just like grapes shrinking into raisins, the moon’s surface will wrinkle as it shrinks. But unlike the pliable grape skin, the lunar surface’s crust is brittle. As the Moon cools and shrinks, the lunar crust fractures into thrust faults—parts of the lunar crust are pushed above adjacent parts.

The research report was published on the 13th in Nature Geoscience, a sub-journal of Nature magazine. The main author is Thomas Waters, a scientist at the Earth and Planetary Research Center of the Smithsonian National Air and Space Museum. Thomas Watters said, “This study proves for the first time that the moon remains tectonically active, and as the moon continues to cool and shrink, moonquakes will occur. Some of these moonquakes can reach magnitude 5 on the Richter scale.”

The scientists analyzed instrument data from astronauts landing on the lunar surface during the Apollo era, as well as more recent data collected by NASA’s Lunar Reconnaissance Orbiter (LRO), the report said. During the Apollo 11, 12, 14, 15, and 16 missions, astronauts placed instruments on the lunar surface. The Apollo 11 seismometer was only operational for three weeks, but the remaining four instruments recorded a total of 28 shallow moonquakes from 1969 to 1977 – which scientists estimate were caused by tectonic faults – ranging in magnitude from 2 to 5 .

A team of scientists has developed a new algorithm that allows them to pinpoint the epicenter of these moonquakes. Subsequently, precise positioning data from the Apollo era was overlaid on the LRO images. The study found that the epicenters of eight of the moonquakes were within 18.6 miles of geological structures called thrust faults. “These eight moonquakes were likely caused by fault slippage,” Waters said. To date, LRO has imaged more than 3,500 fault scarps.

“The moon is not the only body in the solar system that shrinks with age.” NASA said that Mercury’s surface has huge thrust faults – 600 miles long and more than 1 mile high – that shrink more significantly than the moon.

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