Lunar Moonquakes and Faults: A New Discovery at the Lunar South Pole

The lunar south pole, a strategic and intriguing region for space exploration, has recently become the focus of scientific attention due to new discoveries regarding moonquakes and faults. These geological phenomena are believed to be the result of the Moon’s interior gradually cooling and shrinking, a process that has significant implications for future human activities on the Moon.

NASA’s ongoing Artemis campaign, which aims to send astronauts to the lunar south pole, has been aided by data from a NASA-funded study. This research, published in the Planetary Science Journal on January 25, 2024, provides valuable insights into the geological conditions of this region and the potential risks associated with moonquakes and faults.

The study, led by Tom Watters of the Smithsonian Institution, Washington, reveals that the epicenter of one of the strongest moonquakes recorded by the Apollo Passive Seismic Experiment was located in the lunar south polar region. However, the exact location of the epicenter could not be accurately determined. The researchers used a relocation algorithm specifically adapted for very sparse seismic networks to distribute a cloud of possible locations near the pole. This cloud encompasses a number of lobate scarps and many of the proposed Artemis III landing regions.

Lunar Reconnaissance Orbiter Camera (LROC) data has detected thousands of relatively small, young thrust faults widely distributed in the lunar crust. These scarps, which form where contractional forces break the crust and push or thrust it on one side of the fault up and over the other side, are cliff-like landforms that resemble small stair-steps on the lunar surface. They are formed when the lunar crust is pushed together as the Moon contracts, causing the near-surface materials to break and form a thrust fault. The thrust fault carries crustal materials up and sometimes over adjacent crustal materials.

Slip events on existing faults or the formation of new thrust faults trigger shallow moonquakes that can cause strong seismic shaking tens of miles (many tens of kilometers) away from the scarp. The strongest recorded shallow moonquake had an epicenter in the south-polar region, and one young thrust-fault scarp, located within the de Gerlache Rim 2, an Artemis III candidate landing region, is modeled in the study and shows that the formation of this fault scarp could have been associated with a moonquake of the recorded magnitude.

The team also modeled the stability of surface slopes in the lunar south polar region and found that some areas are susceptible to regolith landslides from even light seismic shaking, including areas in some permanently shadowed regions. These areas are of interest due to the resources that might be found there, such as ice.

To better understand the seismic hazard posed to future human activities on the Moon, new seismic data is needed, not just at the South Pole, but globally. Missions like the upcoming Farside Seismic Suite will expand upon measurements made during Apollo and add to our knowledge of global seismicity.

LRO is committed to acquiring data of the lunar surface to aid scientists in understanding important features such as thrust faults. This study is a good demonstration of one of the many ways in which LRO data is being used to assist planning for our return to the Moon.

This research was funded by NASA’s LRO mission, launched on June 18, 2009. LRO is managed by NASA Goddard for the Science Mission Directorate at NASA Headquarters in Washington. With Artemis missions, NASA is exploring the Moon for scientific discovery, technology advancement, and to learn how to live and work on another world as we prepare for human missions to Mars. We will collaborate with commercial and international partners and establish the first long-term presence on the Moon. NASA will land the first woman and first person of color on the Moon, using innovative technologies to explore more of the lunar surface than ever before.

In conclusion, the discovery of moonquakes and faults at the lunar south pole is a significant development for space exploration. As NASA continues to make progress toward sending astronauts to this strategic region, understanding the geological conditions and potential risks is crucial for the success and safety of future missions. The ongoing research and data acquisition efforts, such as those funded by NASA’s LRO mission, will provide valuable insights and contribute to the planning and execution of Artemis missions.