Moonquakes and a Shrinking Moon: New Insights into Lunar Tectonics
Recent research reveals the Moon is still tectonically active and continues to shrink, potentially triggering seismic activity – or moonquakes – in the future. Scientists have identified thousands of small geological structures, known as small mare ridges (SMRs), in the Moon’s maria regions, the dark plains on its surface, leading to this discovery.
Evidence of Ongoing Lunar Activity
The identification and analysis of these SMRs have provided new insights into the mechanisms behind moonquakes and potential risks for future lunar missions. Researchers found these structures to be geologically young, ranging in age from 50 to 310 million years, and widespread across the lunar surface.
Lunar Tectonics: A Different Mechanism Than Earth
Like Earth, the Moon experiences tectonic activity, but the process differs significantly. While Earth’s crust is divided into moving plates that create mountains and volcanoes, the Moon’s crust lacks this plate system. However, internal pressures still shape distinctive landforms. Lobate scarps, ridges formed by compression of the crust, were previously known structures indicating this activity.
The Moon is Shrinking
In 2010, research by Tom Watters of the Smithsonian Institution established that the Moon is slowly shrinking, a process that causes the formation of lobate scarps in the lunar highlands. Recent studies demonstrate that lobate scarps aren’t the sole evidence of this contraction; the newly discovered SMRs in the maria regions appear to be formed by the same compressive forces.
“Since the Apollo era, we have known about the abundance of lobate scarps throughout the Moon’s highlands, but this is the first time scientists have widely documented the existence of similar features throughout the Moon’s mare regions,” said Cole Nypaver of the Smithsonian Institution.
Nypaver added, “This research helps us gain a more complete global perspective on recent Lunar tectonism, which will lead to a greater understanding of the Moon’s interior and its thermal and seismic history, and the potential for future Moonquakes.”
Cataloging Small Mare Ridges
Researchers compiled the first catalog of SMRs on the Moon’s near side, identifying 1,114 new segments, bringing the total number of identified structures to 2,634. The average age of the SMRs is approximately 124 million years, comparable to the age of lobate scarps, which are around 105 million years old.
This finding reinforces the evidence that the Moon remains geologically active and continues to contract. “Our discovery of a small, young ridge in the mare region, as well as findings about its causes, completes the global picture of a dynamic, shrinking Moon,” Watters stated.
The research, published in the journal Planetary Science Journal, is considered crucial for assessing the risk of future moonquakes.