Scientists have created the first global map and analysis of small oceanic ridges (SMRs) on the moon, a distinctive geological feature of tectonic activity. Published in Planetary Science Journal On December 24, 2025, an analysis conducted by scientists at the National Air and Space Museum’s Center for Earth and Planetary Research reveals for the first time that SMR is geologically new and extends across the lunar maria, a vast, dark plain on the moon’s surface. The research team’s findings about how SMRs form introduce a new set of potential lunar earthquake sources that could influence the selection of locations for future moon landings.

Crustal movements are active on both the Moon and the Earth. However, the tectonic forces that affect each celestial body are different. The Earth’s crust is divided into plates that converge, separate, and slide against each other to form vast mountain ranges, deep ocean trenches, and a ring of volcanoes around the Pacific Ocean. Although the Moon’s crust is not divided into plates, stresses within the Moon’s crust give rise to some distinctive landforms. One of the most common of these is foliated scarps, which form when the Earth’s crust is compressed and the resulting forces push material up the adjacent crust along faults, forming ridges. These cliffs, seen in the lunar highlands, only formed within the last billion years, or within the last 20% of the moon’s history.

In 2010, co-author Tom Watters, a senior scientist emeritus at the Center for Earth and Planetary Research, discovered that the moon was slowly shrinking. This contraction led to the formation of foliate cliffs in the lunar highlands. However, the formation of foliated scarps does not explain all of the recent contractional topography on the Moon. Another recently identified class of tectonic landforms is SMR.

SMR is caused by the same forces that form foliated cliffs. However, while foliated cliffs are found at high altitudes, SMRs are only found in Maria. The research team sought to map SMR in the lunar maria and analyze its relationship with recent crustal activity.

“Since the days of Apollo, we’ve known that lobed cliffs are widespread throughout the lunar highlands, but this is the first time scientists have documented a similar widespread spread of features across the lunar mare,” said Cole Kneipaver, a postdoctoral research geologist at the Center for Earth and Planetary Research and lead author of the paper. “This study will help us gain a complete global perspective on recent lunar tectonism on the Moon. This will lead to a deeper understanding of the Moon’s interior and its thermal and seismic history, as well as the potential for future lunar earthquakes.”

The team has compiled the first comprehensive SMR catalog. They discovered 1,114 new SMR segments on the marian side of the moon, increasing the number of known SMRs on the entire moon to 2,634. They also found that the average SMR was 124 million years old, consistent with the average age of the foliation stumps previously found by Watters et al. (105 million years). These ages suggest that, like the foliated scarps, the SMR is one of the youngest geological features on the Moon. Finally, our analysis shows that SMRs form through the same type of faults as foliated scarps, and that highland foliated scarps often transition into mare SMRs, suggesting that the origins of these two structures are similar. Together with the Moon’s high-altitude lobes, the researchers’ SMR data provides a more complete picture of recent contractional crustal activity on the Moon.

“By detecting a young, small bump within Maria and discovering its cause, we now have a complete picture of the dynamically contracting moon,” Watters said.

Possibility of further lunar earthquakes

Previously, Dr. Watters found a link between the tectonic movements that cause the formation of foliated cliffs and the occurrence of lunar earthquakes. The discovery that SMRs originate from the same type of tectonic activity indicates that wherever SMRs exist, lunar earthquakes can also occur beyond the lunar maria. Expanding the list of potential sources of lunar earthquakes creates new opportunities to better understand the Moon’s tectonic movements, but it also indicates that considering the potential for seismic activity increases the risks for humans who may explore or live on the Moon in the future.

“We are in a very exciting time for lunar science and exploration,” Nipaver said. “Future lunar exploration programs like Artemis will provide a wealth of new information about the Moon. A deeper understanding of the Moon’s tectonics and seismicity will directly benefit the safety and scientific success of them and future missions.”

About the National Air and Space Museum

The National Air and Space Museum in Washington, DC, is located at 650 Jefferson Dr. SW and is open from 10 a.m. to 5:30 p.m. every day except December 25. Admission is free, but you will need a timed entry pass to visit. The Stephen F. Udvar-Hazy Center is located near Washington Dulles International Airport in Chantilly, Virginia, and is open from 10 a.m. to 5:30 p.m. every day except December 25. Admission is free and a timed admission pass is not required. Parking fee is $15.

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