A new study published in the Journal of Geophysical Research details the discovery of tens of thousands of seismic events on the moon that were previously unknown to researchers.
The findings were presented at the Lunar and Planetary Science Conference. The space agency explains that billions of years the moon formed vast basins called "mare", which researchers assumed were dead, bereft of any geological activity that likely occurred before dinosaurs were even on Earth.
However, researchers conducted a survey on more than 12,000 images of the moon and found that one mare has been "cracking and shifting as much as other parts of the Moon" and may very well still be happening today. Notably, between 1969 and 1977, seismometers that Apollo astronauts stationed detected around 13,000 moonquakes, and now one researcher has gone back through the Apollo data with a fine-toothed comb and found an additional 22,000 moonquakes, bringing the grand total to around 35,000.
Speaking to Science Magazine, Jeffrey Andrews-Hanna, a geophysicist at the University of Arizona who wasn't involved in the study, said the newly discovered moonquakes show "the moon may be more seismically and tectonically active today than we had thought" and "It is incredible that after 50 years we are still finding new surprises in the data."
"Literally no one checked all of the short-period data before," study author Keisuke Onodera, a seismologist at the University of Tokyo, told Science Magazine.
"We thought there must be many, many more [moonquakes in the data]," Nakamura told Science magazine. "But we couldn't find them."