A research team believes the Moon is more seismically active than previously thought. Analysis of processed Apollo data by US space agency NASA indicates more than 22,000 previously unknown earthquakes. This is almost three times more than the 13,000 earthquakes recorded so far. Results Presented at the 55th Lunar and Planetary Science Conference, March 2024.
Unlike earthquakes, these movements are caused by gradual changes in temperature and meteorite impacts – not by shifting tectonic plates. Because it should not be available on satellite. That is why earthquakes on the Moon are much weaker than on Earth.
During the Apollo missions, seismic measurements were placed on Earth's satellite. Thanks to a new analysis of the data, a total of 35,000 earthquakes have now been recorded. Newly discovered earthquakes show “Moon may be more seismically and tectonically active today than we thought”said Geoffrey Andrews-Hannah, a geophysicist at the University of Arizona Special Journal of Science.
Short and long term data
Apollo astronauts deployed two types of seismometers on the lunar surface. One recorded the 3D movement of seismic waves over a long period of time. Another recorded high-speed tremors over a short period of time. Short-term data have been largely ignored to date because they are severely disturbed by temperature fluctuations between lunar day and lunar night. There were problems with transmitting the data back to Earth, which made estimating the numbers more difficult.
After the Apollo missions ended, NASA withdrew funding for lunar seismometers in favor of new projects. Some short-term data was almost completely lost. Yoshio Nakamura, a now-retired geophysicist at the University of Texas at Austin, recovered a copy of the data on the 12,000 tapes.
These were then digitally converted and study author Keisuke Onodera (a seismologist at the University of Tokyo) spent three months analyzing the data. He used denoising techniques to remove the noise in the data.
The measurements also suggest that these earthquakes occurred at shallower locations than expected. According to Onodera, this suggests that the mechanisms behind some of these earthquakes are more fault-based (a tear or break in the rock) than expected. Onodera and Nakamura hope that future NASA seismic measurements on commercial lunar landers will confirm the results of the new study.
Other options not mentioned by the study group include setting up a fiber optic network on a satellite. It can be used to detect earthquakes over large areas and reduce risks to future lunar colonies.
For sources
Presentation of results at the 55th Lunar and Planetary Science Conference: Lunar seismicity assessment using newly discovered shallow earthquakes (Estimating lunar seismicity from newly discovered shallow earthquakes).
This study was published on October 27, 2023 in the Open Archive of Earth and Space Sciences and is undergoing a peer review process: New insights into lunar seismicity through analysis of newly discovered earthquakes in Apollo short-term seismic data (New Insights into Lunar Seismology through Analysis of Newly Discovered Earthquakes in Short-Term Apollo Seismic Data).
An article in the journal Science appeared on March 20, 2024: The number of earthquakes discovered in the Apollo archive has tripled (The number of earthquakes discovered in the Apollo archives has tripled).
