Skyquakes: The Cannon Fire That Comes From a Clear Blue Sky
The sound arrives without warning. A deep, concussive boom, like distant cannon fire or a door slammed by a giant, rolls in off the water under a cloudless sky. Windows rattle. Dogs bark. People step outside looking for the storm, the explosion, the jet — and find nothing at all. Then it happens again, a month or a year later, and again nobody can say what it was.
The phenomenon is old enough to have collected names on three continents. Along the coast of North Carolina, the booms are called the Seneca Guns, a name borrowed from James Fenimore Cooper's 1850 short story "The Lake Gun," which described mysterious detonations heard around Seneca Lake in upstate New York. In the delta country of Bengal, British colonial officials of the nineteenth century recorded the "Barisal Guns," phantom artillery booming over the waterways near the town of Barisal; the reports were serious enough to be debated in letters to the scientific journal Nature in the 1890s. On the Belgian and Dutch coast, fishermen spoke of mistpouffers, roughly "fog belches." Japan has its uminari, the "cries of the sea," and Italy its brontidi. Different languages, same experience: guns firing where there are no guns.
For a long time the reports were easy to shrug off as folklore. That changed in 2020, when researchers at the University of North Carolina took the problem to the instruments. Between 2013 and 2015, the EarthScope Transportable Array, a rolling network of roughly 400 seismic and atmospheric sensors, had swept across the eastern United States. The team matched its recordings against local news reports of booms in the Cape Fear region and found the events clearly captured: bursts of sound lasting from about one to ten seconds. The crucial discovery was negative. No earthquake, however small, showed up in the ground at the same time. Whatever makes the Seneca Guns travels through the air, not the crust.
That finding narrowed the field without settling it. Bolides, small meteors detonating in the upper atmosphere, can produce exactly such booms, but they should be visible as fireballs far more often than anything witnesses describe. Atmospheric ducting, in which temperature layers bend sound waves back to earth, can carry distant thunder, ocean storms or military exercises over surprising distances, yet many booms occur when no such source can be found offshore. Shallow seismic slips too small to register, collapsing undersea slopes and even eruptions of methane gas from the seabed have all been proposed. Each idea fits some cases and fails others, and the oldest accounts predate supersonic aircraft, the explanation of last resort, by generations.
That is the real puzzle of the skyquakes: not that they lack an explanation, but that they have too many, none of which covers Bengal, Belgium and the Carolinas at once. The booms are real, recorded and measured. Their source, after several centuries of listening, remains officially unknown. Somewhere off a quiet coast, the next one is already on its way.