Moon is more geologically active than previously believed

Moon is more geologically active than previously believed
by Clarence Oxford
Los Angeles CA (SPX) Jan 29, 2025

The moon's surface has long been a subject of study, offering clues about its geological and evolutionary history. Dark, flat regions known as lunar maria, which are filled with solidified lava, were thought to have formed through significant compression billions of years ago. Many researchers concluded that these regions have remained dormant ever since. However, a new study indicates that the moon's subsurface activity may still be ongoing.

Scientists from the Smithsonian Institution and the University of Maryland have found evidence suggesting that small ridges on the moon's far side are much younger than the previously studied formations on its near side. Their findings, published in The Planetary Science Journal on January 21, 2025, challenge the assumption that the moon has been geologically static for billions of years.

"Many scientists believe that most of the moon's geological movements happened two and a half, maybe three billion years ago," said Jaclyn Clark, assistant research scientist in the Department of Geology at UMD. "But we're seeing that these tectonic landforms have been recently active in the last billion years and may still be active today. These small mare ridges seem to have formed within the last 200 million years or so, which is relatively recent considering the moon's timescale."

The researchers utilized advanced mapping and modeling techniques to identify 266 previously unknown small ridges on the moon's far side. These ridges were typically grouped in clusters of 10 to 40 within volcanic regions that formed approximately 3.2 to 3.6 billion years ago. The team's analysis suggests that these ridges emerged in narrow areas with underlying weaknesses in the lunar surface. To determine their age, the researchers used a method called crater counting, which involves estimating surface age based on the number of impact craters.

"Essentially, the more craters a surface has, the older it is; the surface has more time to accumulate more craters," Clark explained. "After counting the craters around these small ridges and seeing that some of the ridges cut through existing impact craters, we believe these landforms were tectonically active in the last 160 million years."

The study found that the far-side ridges bear a structural resemblance to those on the near side, indicating they may have been shaped by similar forces. These forces likely include the moon's gradual contraction and shifts in its orbit. Decades ago, the Apollo missions detected shallow moonquakes, and the new findings suggest that these ridges might be associated with similar seismic activity. Understanding these dynamics could play a critical role in planning future lunar missions.

"We hope that future missions to the moon will include tools like ground-penetrating radar so researchers can better understand the structures beneath the lunar surface," Clark said. "Knowing that the moon is still geologically dynamic has very real implications for where we're planning to put our astronauts, equipment and infrastructure on the moon."

Research Report:Recent Tectonic Deformation of the Lunar Far Side, Maria and South Pole Aitken Basin