The Moon is slowly shrinking as its interior cools, and that contraction is generating faults and seismic activity in the very region where NASA plans to land astronauts. A study published in The Planetary Science Journal, led by Smithsonian senior scientist emeritus Thomas R. Watters, models a potential magnitude 5.3 shallow moonquake along a thrust-fault scarp near the lunar south pole, with shaking strong enough to destabilize steep crater walls. The findings raise direct questions about how engineers and mission planners should design habitats and select landing sites for the Artemis campaign.
A Shrinking Moon and the Faults It Creates
Over the last several hundred million years, the Moon has contracted by roughly 50 meters as its molten core gradually cools, a figure highlighted in NASA’s discussion of the shrinking crust. That may sound minor on a body more than 3,400 kilometers wide, but the effect on the brittle outer shell is significant. Unlike Earth, the Moon lacks tectonic plates that can absorb stress through subduction or spreading. Instead, the global shrinkage compresses the entire crust, forcing sections of rock to break and thrust upward over neighboring blocks, forming cliff-like landforms known as lobate scarps that can stretch for kilometers and rise tens of meters above the surrounding terrain.
These scarps are not ancient relics frozen in time. High-resolution imaging from the Lunar Reconnaissance Orbiter shows that young lobate thrust-fault scarps are widely distributed across the Moon and rank among its youngest surface features, based on the way they cut across small impact craters. Their crisp appearance, sharp edges, and lack of overprinting by later impacts indicate that the Moon’s crust is still being reshaped by internal cooling today. That ongoing deformation is the engine behind the seismic risk now drawing attention from planetary scientists and space agencies, especially as human activity is poised to return to the lunar surface.
What Apollo Seismometers Revealed
The only direct seismic measurements ever taken on the Moon came from instruments deployed by Apollo astronauts between 1969 and 1977. During that period, the network recorded 28 shallow moonquakes, as detailed in a reanalysis of Apollo data that revisited the original seismic records with modern techniques. That study relocated the epicenters of several events to positions close to mapped thrust-fault scarps, strengthening the case that at least some of these quakes were caused by slip along contractional faults rather than by impacts or deep interior processes. The link between young scarps and shallow quakes suggests that the Moon’s tectonic engine is still active on human timescales.
One distinctive feature of lunar seismic signals is their duration. Because the Moon’s near-surface is extremely dry, fractured, and lacks an atmosphere, it forms what seismologists describe as a high-Q environment, where seismic waves lose energy very slowly. Vibrations scatter and reverberate through the fractured crust for far longer than they would on Earth, producing emergent oscillations that can “ring” the Moon like a bell. For any future structure sitting on or near the surface, that prolonged shaking would impose repeated stress cycles well beyond what a comparable earthquake would deliver on our planet, raising design questions about fatigue, resonance, and anchoring in low gravity.
Modeled Hazards at the South Pole
The study led by Watters goes beyond historical data to project what a strong shallow moonquake could do at the south pole, where Artemis missions are targeting permanent infrastructure. Using numerical simulations, the team modeled a potential event of approximately magnitude 5.3 associated with a south-polar thrust-fault scarp, describing the scenario in a recent journal analysis of ground motion. They mapped the predicted peak ground acceleration as a function of distance from the fault, finding that even at tens of kilometers away, shaking levels could be high enough to matter for engineered structures. In the Moon’s one-sixth gravity and vacuum, loose regolith may respond differently than soil on Earth, with particles more prone to lofting and sliding under repeated jolts.
The same modeling assessed slope stability for steep south-polar crater walls, including those around Shackleton crater, one of the most discussed candidate sites for a long-term base because of its persistently shadowed interior, which may harbor water ice. Simulations indicate that seismic shaking from a nearby fault rupture could trigger landslides on these slopes, potentially mobilizing blocks and regolith down into areas that might host infrastructure or scientific instruments. That finding complicates the calculus for mission planners: the very craters that offer the best resource potential also sit in a zone of active faulting and elevated landslide risk, forcing a trade-off between access to ice, illumination, communications, and geological stability.
Implications for Artemis Landing Sites
NASA has identified multiple candidate landing regions near the south pole for its Artemis campaign, and the agency’s own mapping now overlays those regions with relocated epicenter probability clouds and mapped scarps. In its overview of how a shrinking Moon affects the south pole, NASA notes that several proposed sites lie within tens of kilometers of potential fault-related epicenters. The overlap between promising resource zones and active fault traces is not trivial. While the odds of a significant shallow quake occurring during any single short-duration sortie are low, the risk profile changes sharply for a surface habitat expected to operate for many years, particularly if it is situated near steep topography.
Most public discussion of Artemis focuses on propulsion systems, life support, and international partnerships, but the seismic dimension is becoming harder to ignore as more detailed models emerge. The Moon is popularly imagined as geologically dead, yet the contractional faults identified across its surface are young, the quakes recorded by Apollo were real, and the latest simulations tie both phenomena directly to south-polar terrain that astronauts are likely to traverse. Habitat designers will need to account for ground motion and long-duration shaking in a way that no previous lunar architecture has attempted, potentially favoring low-profile, flexibly mounted structures or partially buried modules that can ride out vibrations with reduced risk of tipping or structural damage.
Filling the Data Gap With New Instruments
A central limitation of current risk models is that no seismic instrument has operated on the Moon since the Apollo network went silent in 1977, leaving a gap of nearly five decades in direct observations. NASA’s planned Farside Seismic Suite, or FSS, is intended to close that gap by deploying a modern seismometer package to the lunar far side. Drawing on heritage from the InSight mission’s sensor that recorded marsquakes, the FSS payload is described in a mission briefing as the first dedicated seismic station on the Moon since Apollo and the first ever on the far side, where Earth-based radio interference is naturally shielded.
When FSS begins collecting data, scientists will be able to compare real-time seismic activity with the patterns inferred from Apollo-era records and from surface fault mapping, providing a much clearer picture of how often shallow quakes occur and how strong they are. Continuous monitoring will help distinguish between different sources of moonquakes, such as thermal contraction, tidal stresses from Earth, and fault slip related to global contraction. Those measurements, in turn, can feed directly into engineering standards for lunar construction, informing everything from allowable building heights to anchoring strategies and safe standoff distances from steep slopes and fault traces.
Designing for a Living, Shrinking World
The emerging view of the Moon as a slowly contracting, tectonically active body has direct implications for how humanity should build there. Engineers will need to consider not only the static loads imposed by reduced gravity but also dynamic loads from repeated shaking, with an eye toward avoiding resonant frequencies that could amplify motion. Structures may benefit from flexible joints, shock-absorbing foundations, or partial burial in regolith berms that can dampen vibrations. Landing pads, fuel depots, and mobility corridors will likely be sited with conservative setbacks from scarps and crater rims to reduce exposure to landslide debris in the event of a strong shallow moonquake.
For mission planners and the broader public, keeping up with these evolving insights will be an ongoing task as new data arrive from orbital imagers, landers, and seismic packages. NASA’s outreach platforms, including its curated science series, are increasingly highlighting how planetary geology intersects with human exploration. As Artemis moves from concept to sustained presence, the Moon’s subtle but persistent tectonic activity will shift from a scientific curiosity to a core design constraint, shaping where we land, how we build, and how safely we can inhabit our nearest celestial neighbor.
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*This article was researched with the help of AI, with human editors creating the final content.
