A new study analyzing 15 years of lunar images shows that internal seismic activity, not meteorite impacts, is the primary trigger for the Moon’s most recent landslides. The findings reveal that the lunar interior is still geologically active, challenging long-held assumptions about our celestial neighbor.
The Lunar Reconnaissance Orbiter Wide Angle Camera captured this mosaic of the Moon as it appeared during the Aug. 30, 2023, Super Blue Moon. Credit: NASA/GSFC/Arizona State University
- New research has identified 41 small-scale landslides on the lunar surface since 2009, indicating that the Moon is more geologically active than previously thought.
- Analysis of multi-temporal imagery from NASA’s Lunar Reconnaissance Orbiter Camera (LROC) concluded that endogenous Moon shocks, rather than meteorite impacts or thermal weathering, are the major trigger for these active landslides.
- Most of the recent landslides have occurred in specific areas, such as the eastern Imbrium Basin, indicating ongoing seismic activity in these areas.
- These findings provide important insights into contemporary lunar geological processes, informing geo-threat assessments and mission planning for future human exploration and permanent bases on the Moon.
The Moon may seem like a lifeless, unchanged world, but new research suggests it is more geologically active than previously thought. A team of Chinese scientists has identified 41 new landslides on the lunar surface since 2009, and concluded that they were likely caused by seismic activity. This discovery has important implications for our understanding of lunar geology and the safety of future Moon bases.
Study, published in journal national science reviewtackles an important question about the Moon’s geology: What causes its myriad small landslides? By analyzing images of 74 locations over 15 years from NASA’s Lunar Reconnaissance Orbiter Camera (LROC), researchers tested leading theories of impacts by comparing them to inner Moon earthquakes. Their conclusion: Endogenous Moon earthquakes (seismic activity starting below the surface), not meteorite impacts, are the dominant force behind the Moon’s currently active landslides.
“Our work reminds us that the Moon is not a static, dead world – in addition to abundant new impacts, landslides are still active today,” Xiong Xiao, a professor at Sun Yat-sen University and lead author of the paper, said in a Sept. 29 press release. “These insights bridge a gap between past lunar history and current processes, advancing both science and mission planning.”
History of landslides on the Moon
For decades, scientists have wondered what causes widespread landslides on the Moon. These events are an important process in shaping the lunar landscape and represent a potential, but understudied, geopotential threat to future exploration. While ancient landslides can be massive, the 41 newly identified events are much smaller, typically less than about two-thirds of a mile (1 kilometer) long. This new research helps solve the long-standing mystery of their trigger, pinpointing the Moon’s earthquakes as the primary cause and suggesting that the same forces were responsible for landslides in the Moon’s distant past.
identifying landslides
To capture these recent changes, the research team led by Xiao began a careful search. They focused on the “least stable regions” of the Moon – the steep slopes between 24 and 42 degrees, the areas most likely to give way of material under gravity. These include the steep walls of young impact craters, long ridges raised by tectonic faults within the last 1.1 billion years, and irregular mare patches (mysterious, mounded areas of volcanic rock that may indicate recent volcanic activity).
The team analyzed 562 pairs of high-resolution, multi-temporal images captured by NASA’s LROC between 2009 and 2024. The images covered 74 different observation targets spanning both the near and far sides of the Moon to ensure a globally representative sample. To recognize subtle differences between photographs taken years apart, scientists carefully put “before” and “after” images together, aligning them and taking into account any changes in lighting. As a result, they identified 41 new, smaller-scale landslides.
What causes landslides?
After identifying the landslide, scientists worked to determine the trigger. For 29 percent of the landslides (12 of 41), they found a strong spatial correlation with a new effect – a small crater, often less than 6.5 feet (2 meters) wide, appearing at the landslide’s starting point. However, researchers stopped short of confirming the direct cause. Due to the large gap of time between the before and after images, they could not be certain that both events occurred at the same time.
Furthermore, these landslides occurred on slopes that were already highly unstable and near their breaking point. Evidence suggests that in some of these cases, small impacts may have provided a final, gentle push to material that was already ready to collapse. The ground shaking from these small impacts must have been incredibly localized because other nearby rocks on the same slope showed no signs of movement. This, combined with the fact that some recent large lunar impacts did not cause landslides, led the team to demonstrate that impacts are not an efficient landslide trigger.
The team also examined another possibility: thermal weathering. The surface of the Moon experiences rapid temperature changes every day. This continued stress could theoretically crack and fracture the exposed rocks, causing them to crumble and slide. However, when researchers examined the starting points of the landslides, they found no evidence of exposed rock. Instead, the areas were covered with a layer of regolith (lunar soil), which acts as a powerful insulator, protecting any rock from extreme temperatures. With no weak rocks to break, the team ruled out thermal weathering as a possible trigger.
By eliminating other possibilities, the researchers concluded that endogenous Moon earthquakes were the only plausible driver for the majority – 71 percent – of the new landslides. This conclusion was strengthened by the location of the landslide. They were not distributed randomly; Most were concentrated in the eastern Imbrium basin. The Apollo seismometers had detected seismic activity in the region decades earlier, but conventional wisdom held that the activity had stopped since then. The new findings suggest that this area may be a currently active lunar seismic zone.
Importance for future lunar missions
As plans for permanent Moon bases gain momentum, understanding the current geologic activity of the Moon is more important than ever. “Understanding today’s landslide activity and its drivers is essential to assessing geohazard risk for these future missions,” Xiao said. While the newly discovered landslides are small, the findings serve as an important warning: Future lunar facilities should not be built near steep slopes in seismically active areas such as the eastern Imbrium Basin. Landslide locations also provide a map of potential seismic hotspots, guiding future exploration of the Moon’s interior without the need for a planet-wide network of sensors.
