Smithsonian planetary scientists discover recent tectonic activity on the Moon

(Press-News.org) Scientists have produced the first global map and analysis of small mare ridges (SMRs) on the moon, a characteristic geological feature of tectonic activity. Published in The Planetary Science Journal Dec. 24, 2025, the analysis performed by scientists at the National Air and Space Museum’s Center for Earth and Planetary Studies and colleagues reveals for the first time that SMRs are geologically young and are widespread across the lunar maria—the vast, dark plains on the moon’s surface. The team’s discovery of how SMRs form introduces a new set of potential moonquake sources that could affect future site selections for lunar landings.

Both the moon and the Earth are tectonically active; however, the tectonic forces affecting each body are different. Earth’s crust is divided into plates that have converged, separated, and slide past each other to produce expansive mountain ridges, deep ocean trenches and a ring of volcanoes around the Pacific Ocean. The moon’s crust is not divided into plates, yet stresses within the lunar crust give rise to several distinctive landforms. One of the most common of these is lobate scarps, which form when the crust compresses and the resulting forces push material up and over adjacent crust along a fault, creating a ridge. These scarps, found in the lunar highlands, have formed only within the last billion years, or 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 Studies, discovered that the moon is slowly shrinking. This contraction caused the lobate scarps in the lunar highlands to form. Yet the formation of lobate scarps does not account for all the recent contractional landforms on the moon. Another recently identified class of tectonic landforms is SMRs.

SMRs are caused by the same forces that form lobate scarps. But while lobate scarps are found in the highlands, SMRs are found only in the maria. The research team sought to map out SMRs in the lunar maria and analyze their connection to recent tectonic activity.

“Since the Apollo era, we’ve known about the prevalence of lobate scarps throughout the lunar highlands, but this is the first time scientists have documented the widespread prevalence of similar features throughout the lunar mare,” said Cole Nypaver, a post-doctoral research geologist at the Center for Earth and Planetary Studies and the first author on the paper. “This work helps us gain a globally complete perspective on recent lunar tectonism on the moon, which will lead to a greater understanding of its interior and its thermal and seismic history, and the potential for future moonquakes.”

The team compiled the first exhaustive SMRs catalog. They discovered 1,114 new SMR segments across the nearside lunar maria, increasing the number of known SMRs across the moon to 2,634. They also found that the average SMR was 124 million years old, consistent with the average age of lobate scarps (105 million years old), previously found by Watters and colleagues. Those ages suggest that, like the lobate scarps, the SMRs are among the youngest geologic features on the moon. Finally, the analysis shows that SMRs formed via the same type of faults as lobate scarps, and that lobate scarps in the highlands often transition to SMRs in the mare, suggesting a similar origin for these two structures. Together with lobate scarps in the lunar highlands, the team’s SMR data provide a more complete picture of recent contractional tectonic activity on the moon.

“Our detection of young, small ridges in the maria, and our discovery of their cause, completes a global picture of a dynamic, contracting moon,” Watters said.

The Potential for More Moonquakes

Previously, Watters found a link between the tectonic activity that causes lobate scarps to form and the incidence of moonquakes. The discovery that SMRs originate from the same type of tectonic activity indicates that moonquakes could also occur across the lunar maria, anywhere an SMR is present. Expanding the list of potential sources for moonquakes creates new opportunities to better understand the tectonics of the moon, but it also shows an elevated risk for humans who might explore or live on the moon in the future, given the potential for seismic activity.

“We are in a very exciting time for lunar science and exploration,” Nypaver said. “Upcoming lunar exploration programs, such as Artemis, will provide a wealth of new information about our moon. A better understanding of lunar tectonics and seismic activity will directly benefit the safety and scientific success of those and future missions.”   

About the National Air and Space Museum

            The National Air and Space Museum in Washington, D.C., is located at 650 Jefferson Dr. S.W. and is open every day except Dec. 25 from 10 a.m. to 5:30 p.m. Admission is free, but timed-entry passes are required to visit. The Steven F. Udvar-Hazy Center is located in Chantilly, Virginia, near Washington Dulles International Airport and is open every day except Dec. 25 from 10 a.m. to 5:30 p.m. Admission is free, timed-entry passes are not required, and parking is $15.

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