Shrinking Moon Triggering Moonquakes, New Study Reveals
- The Moon, our closest celestial neighbor, is continuing to shrink, a process that is triggering new tectonic activity and raising the possibility of more frequent moonquakes.
- Scientists have known for some time that the Moon is cooling and contracting, a process that began hundreds of millions of years ago.
- While both Earth and the Moon experience tectonic forces, the mechanisms are fundamentally different.
The Moon, our closest celestial neighbor, is continuing to shrink, a process that is triggering new tectonic activity and raising the possibility of more frequent moonquakes. Recent research, published on , details the discovery of over a thousand previously unknown tectonic ridges across the lunar maria – the dark, basaltic plains visible from Earth – providing evidence of this ongoing contraction.
This isn’t a sudden development. Scientists have known for some time that the Moon is cooling and contracting, a process that began hundreds of millions of years ago. As the lunar interior cools, the surface wrinkles and cracks, much like a drying apple. This contraction creates stress within the Moon’s crust, leading to the formation of thrust faults and, potentially, moonquakes.
How Lunar Tectonics Differ from Earth’s
While both Earth and the Moon experience tectonic forces, the mechanisms are fundamentally different. Earth’s crust is composed of moving plates that collide, separate, and slide past each other, resulting in mountain building, ocean trenches, and volcanic activity. The Moon, however, lacks these mobile plates. Instead, stress accumulates within its single, continuous crust. This stress manifests as distinctive landforms, including lobate scarps – cliff-like features formed by compression – and, more recently identified, small mare ridges (SMRs).
Lobate scarps were initially identified as evidence of the Moon’s shrinking. However, they don’t fully explain all the observed features related to this contraction. SMRs, a different class of surface feature, have now been found to play a significant role. These ridges form from the same compressive forces that create the lobate scarps, but they are located specifically within the lunar maria.
Mapping the Moon’s Shrinking
Researchers created the first global map and detailed study of these small mare ridges (SMRs). The study, published in The Planetary Science Journal, identified 1,114 previously undocumented SMR segments on the near side of the Moon, bringing the total number of known SMRs to 2,634. Analysis indicates that the average age of these ridges is approximately , remarkably similar to the average age of lobate scarps (). This similarity suggests a common origin and ongoing tectonic activity.
“Since the Apollo era, we’ve known about the prevalence of lobate scarps across the lunar highlands, but this is the first time scientists have documented the widespread prevalence of similar features across the lunar maria,” explained Cole Nypaver, a postdoctoral research geologist at the Center for Earth and Planetary Studies and lead author of the study.
The Link to Moonquakes
Previous research has established a connection between the tectonic forces that form lobate scarps and the occurrence of moonquakes. Because SMRs are formed through the same types of faulting, they are also considered potential sources of seismic activity. This is particularly relevant as we prepare for a renewed era of lunar exploration.
Understanding the distribution of potential moonquake sources is crucial for planning safe landing sites for future missions, including NASA’s Artemis program, which aims to return humans to the Moon. Seismic activity could pose challenges to lunar habitats and equipment.
Implications for Future Lunar Missions
The discovery of these SMRs and their potential link to moonquakes isn’t necessarily a cause for alarm, but it does highlight the need for a more comprehensive understanding of the Moon’s internal processes and seismic hazards. The new catalog of SMRs, combined with existing data on lobate scarps, provides a more complete picture of the Moon’s recent contraction and tectonic evolution.
“Our findings will help to complete a global view of recent lunar tectonism, which will lead to a better understanding of its interior, thermal history, and seismicity, as well as potential future moonquakes,” Nypaver stated.
As Tom Watters, a senior scientist emeritus at the Center for Earth and Planetary Studies, noted, “Our discovery of young, small ridges in the maria, and the understanding of their cause, complements the global picture of a dynamic, shrinking Moon.”
The ongoing study of the Moon’s tectonic activity is not only essential for ensuring the safety of future lunar missions but also provides valuable insights into the evolution of terrestrial planets and the processes that shape their surfaces. Continued exploration and research will undoubtedly reveal further details about our celestial neighbor and its dynamic history.