For over two centuries, people across the globe—from Belgium and Japan to the United States—have reported hearing inexplicable booming sounds known as “skyquakes.” Often resembling artillery fire or massive backfires, these auditory phenomena remain a scientific puzzle. Historical records date back to 1811, when residents in New Madrid, Missouri, reported strange noises during a 7.2-magnitude earthquake. Similar sounds, dubbed “Seneca Guns,” were documented near New York’s Seneca Lake in 1850, leading author James Fenimore Cooper to describe the “deep, hollow” explosions as defying natural laws.

Scientists have long speculated about the origins, proposing theories ranging from military exercises and quarry blasts to exploding meteors. In 2020, a team from the University of North Carolina at Chapel Hill attempted to solve the mystery by cross-referencing news reports with data from the EarthScope Transportable Array, a massive network of seismic stations.

Their findings suggested the noise likely originates in the sky rather than the ground. Researcher Eli Bird noted that while the team suspects an atmospheric phenomenon—perhaps amplified crashing ocean waves or space rocks entering the atmosphere—they generally ruled out seismic activity as the direct cause. Despite these efforts, definitive answers remain elusive. When a massive boom shook 15 Alabama counties in 2017, the National Weather Service found no evidence of an explosion, admitting they could only hypothesize along with the public.