Although it’s not easy to observe from Earth, the Moon is gradually shrinking as it cools down. The shrinkage occurs at a rate of about 45 meters (more than 150 feet) every few hundred million years. A recent study conducted in the US suggests that this slow process could lead to landslides and quakes near the lunar South Pole. This research is particularly significant as NASA is considering landing astronauts in this area in the future. It is crucial to avoid building a space station in a geologically unstable zone.”Our modeling suggests that shallow moonquakes capable of producing strong ground shaking in the south polar region are possible from slip events on existing faults or the formation of new thrust faults,” stated planetary scientist Tom Watters from the Smithsonian Institution.”The global distribution of young thrust faults, their potential to be active, and the potential to form new thrust faults from ongoing global contraction should be considered when planning the location and stability of permanent outposts on the Moon.”The study focused on lobate scarps, extended ridges thought to be caused by tectonic activity. Recent imagery from the Lunar Reconnaissance Orbiter was analyzed in combination with recordings from the seismometers placed during the Apollo missions, which operated until 1977.
How lobate scarps are thought to form. (Arizona State University/Smithsonian)The analysis suggested that one of the most powerful moonquakes ever recorded by the Apollo seismometers, a magnitude 5 quake lasting several hours, could have been caused by one of the lobate scarps observed near the Moon’s South Pole – and on the Moon, it doesn’t take much to trigger a serious landslide.
Image showing possible moonquake epicenters (magenta dots), lobate scarps (red lines), and potential NASA landing spots (blue squares). (NASA/LRO/LROC/ASU/Smithsonian Institution)”You can think of the Moon’s surface as being dry, grounded gravel and dust,” explained geologist Nicholas Schmerr from the University of Maryland.”Over billions of years, the surface has been hit by asteroids and comets, with the resulting angular fragments constantly getting ejected from the impacts.””As a result, the reworked surface material can be micron-sized to boulder-sized, but all very loosely consolidated. Loose sediments make it very possible for shaking and landslides to occur.”Currently, scientists have limited data regarding the frequency and location of moonquakes. However, any insights, like those provided by the findings of this new study, will be valuable in planning future Moon landings and lunar bases.”As we get closer to the crewed Artemis mission’s launch date, it’s important to keep our astronauts, our equipment and infrastructure as safe as possible,” emphasized Schmerr.”This work is helping us prepare for what awaits us on the Moon – whether that’s engineering structures that can better withstand lunar seismic activity or protecting people from really dangerous zones.”The research has been published in the Planetary Science Journal.
