Did you know that the Moon, our celestial companion, is still alive with activity? Recent research has revealed that quakes on the Moon are far more widespread than we ever imagined. The dark, basalt plains, which cover a significant portion of the lunar surface, are not as geologically quiet as previously thought. These plains, formed from ancient volcanic activity, are now known to be teeming with fault ridges, or small mare ridges (SMRs), which are compressional tectonic features. These SMRs are not just ancient formations; some are just a few tens of millions of years old, relatively recent in geological terms. This discovery provides a clearer picture of the Moon's ongoing slow shrinkage and wrinkling, much like an old apple drying out. The findings suggest that the Moon's dark basalt plains, prime targets for future missions and potential long-term bases, are not as stable as we thought. Geologist Cole Nypaver from the Smithsonian Institution's Center for Earth and Planetary Studies explains, 'This work helps us gain a globally complete perspective on recent lunar tectonism, which will lead to a greater understanding of its interior and its thermal and seismic history, and the potential for future moonquakes.' The Moon, after all, doesn't have tectonic plates like Earth, but it does have its own internal activity. The SMRs, which appear to have formed around the same time as the lobate scarps (ridge-like formations in the rocky lunar highlands), have been mapped globally and analyzed as part of a unified contraction system. This has revealed that the lunar maria have shrunk by roughly 0.003 to 0.004 percent, a tiny fraction but comparable to the contraction in the highlands. This similarity suggests that the same global stresses are shaping both terrains. The Moon's shrinkage has left its mark on both the rocky highlands and the smooth, dark volcanic plains. This discovery dramatically expands the inventory of possible seismic sources on the Moon, broadening our toolkit for understanding the Moon's ongoing evolution. The widespread presence of recently or currently seismically active tectonic features across the maria provides new opportunities for future lunar missions and investigations. The distribution of SMRs may also be of relevance to any long-term lunar habitation due to the hazards that shallow moonquakes pose to human-made lunar infrastructure. The research has been published in The Planetary Science Journal.
