A study published in The Planetary Science Journal on October 14, 2026, reports more than 10,000 young fault-related landforms mapped across the Moon. The count covers two types of terrain feature—lobate scarps and small mare ridges—while the paper assesses seismic activity through a separate set of observations. The study draws on images from the Lunar Reconnaissance Orbiter Camera (LROC).
What the lunar map counts
The study reports more than 8,900 lobate scarps and more than 2,600 small mare ridges (SMRs), two distinct landform populations associated with lunar contraction.
| Mapped landform | Study count | Scope |
| Lobate scarps | More than 8,900 | Mapped thrust-fault scarps |
| Small mare ridges (SMRs) | More than 2,600 | Mapped ridges in the lunar maria |
A lobate scarp is a low, curved ridge formed where the Moon’s crust is pushed together along a thrust fault. The study’s scarp survey comprises about 127,800 mapped segments; roughly 5,470 scarps are longer than 1 kilometer.
How LROC imagery built the survey
The researchers used Narrow Angle Camera imagery and mosaics with resolutions of 0.5–2 meters per pixel, alongside monochrome Wide Angle Camera mosaics at 100 meters per pixel. Within 45 degrees of the equator, the study reports more than 90% coverage at the Narrow Angle Camera’s optimum incidence angles. More than 70% of the area was imaged under both east- and west-lighting conditions.
Those details describe the image coverage behind the inventory. They also give the count context: the study maps visible geological features across a broad area, using two camera systems with different spatial resolutions.
Why the contraction rate has two estimates
The study estimates that late-stage contraction reduced the Moon’s radius by 42–46 meters, equivalent to an estimated areal contraction of 0.0048%–0.0053%. The radius estimate varies with the assumed dip angle of the thrust faults; the estimate is about 44 meters at a 30-degree dip.
The implied rate depends on how long the contraction is assumed to have occurred. Here, Ma means a million years:
| Assumed start of thrust faulting | Estimated contraction rate | Model condition |
| About 400 million years ago | About 11 cm/Ma | Assumes generally uniform contraction over that interval |
| About 800 million years ago | About 6 cm/Ma | Assumes generally uniform contraction over that interval |
These are alternative estimates built from the same modeled contraction over different assumed time spans. The paper does not present either as a direct measurement of a constant present-day rate.
What the moonquake evidence suggests
An earlier analysis of Apollo seismic-network data placed 13 of 28 relocated shallow-moonquake epicenters within 90 kilometers of a lobate scarp. The study’s authors treat that proximity as evidence relevant to a connection between some young thrust faults and shallow moonquakes.
The paper also discusses landslides near young faults identified in repeat LROC images. Its authors interpret seismic shaking from fault slip as a likely trigger for those landslides, and describe the fault population as a potential seismic hazard worth considering.
