Over Ten Thousand Young Faults Mapped Across a Shrinking Moon
The Moon is steadily contracting as its interior cools, a process that has generated more than 10,000 young geological faults across its surface and reduced its radius by roughly 45 meters over the past several hundred million years, according to an study published in The Planetary Science Journal. The findings detail how the lunar crust fractures under tectonic stress because our single-plate satellite lacks the shifting tectonic plates found on Earth. Thomas Watters of the Smithsonian led the research team analyzing millions of images from the Lunar Reconnaissance Orbiter Camera.
Cooling Interiors Cause the Lunar Crust to Crack
Formed approximately 4.5 billion years ago following a violent collision between early Earth and a massive planetary body, the Moon has never finished cooling its interior. As the interior loses heat, its volume diminishes, but the cold and rigid outer shell cannot simply wrinkle smoothly. Instead, the brittle crust cracks under the resulting pressure, creating faults where one section of rock is pushed upward over another. Journal des Femmes noted that this transformation resembles a drying grape shrinking into a raisin, though lunar rock fractures rather than folds softly.
The study calculates that the lunar radius shrank by approximately 45 meters, or 148 feet, over the course of 400 million to 800 million years. This contraction rate translates to a decrease of 6 to 11 centimeters per million years, a pace vastly slower than Earth’s moving tectonic plates. A thick, porous layer of pulverized rock known as megarégolithe initially acted as a thermal blanket, trapping internal heat and delaying the widespread fracturing seen today.
Implications for Artemis and Lunar Base Placement
These young faults and resulting moonquakes present a distinct challenge for future human outposts, particularly the missions planned under NASA’s Artemis program near the lunar south pole. A prior 2024 study by Watters’ team linked surface faults in that polar region to a magnitude five moonquake recorded by Apollo instruments in the 1970s.
Selecting a safe location for permanent bases requires factoring in the distribution of these active faults. According to Smithsonian data cited by Journal des Femmes, regions with thicker crust contain fewer faults and appear more stable than heavily fractured areas. However, a 2022 study estimated weaker tremors and avoided most candidate sites for Artemis.
