They have been reported from an Adriatic island in 1824; Western Australia, South Australia and Victoria in Australia; Belgium; frequently on calm summer days in the Bay of Fundy, Canada; Lough Neagh in Northern Ireland; Scotland; Passamaquoddy Bay, New Brunswick; Cedar Keys, Florida; Franklinville, New York in 1896; and northern Georgia in the United States. Their sound has been described as being like distant but inordinately loud thunder while no clouds are in the sky large enough to generate lightning. Those familiar with the sound of cannon fire say the sound is nearly identical. The booms occasionally cause shock waves that rattle plates. Early white settlers in North America were told by the native Haudenosaunee Iroquois that the booms were the sound of the Great Spirit continuing his work of shaping the earth. The terms "mistpouffers" and "Seneca guns" both originate in Seneca Lake, NY, and refer to the rumble of artillery fire. James Fenimore Cooper, author of The Last of the Mohicans, wrote "The Lake Gun" in 1850, a short story describing the phenomenon heard at Seneca Lake, which seems to have popularized the terms.
Hypotheses
Their origin has not been positively identified. They have been explained as:
Coronal mass ejection CMEs often generate shock waves similar to what happens when an aircraft flies at a speed higher than the speed of sound in Earth's atmosphere. The solar wind's equivalent of a sonic boom can accelerate protons up to millions of miles per minute—as much as 40 percent of the speed of light.
Meteors entering the atmosphere causing sonic booms.
Gas:
*Gas escaping from vents in the Earth's surface.
*With lakes, bio gas from decaying vegetation trapped beneath the lake bottoms suddenly bursting forth. This is plausible, since Cayuga Lake and Seneca Lake are two large and deep lakes.
*Explosive release of less volatile gases generated as limestone decays in underwater caves.
Military aircraft.
In some cases, they have been associated with earthquakes. Earthquakes may not hold as a general cause because these sounds are often unaccompanied by seismic activity, other than the vibrations induced by sound.
In North Carolina, one speculation is that they are the sound of pieces of the continental shelf falling off into the Atlanticabyss. However, the Atlantic abyss is too far away from the east coast, and the Atlantic ridge is the result of very slow-moving tectonics and could not produce such sounds, given how often they occur.
Underwater caves collapsing, and the air rapidly rising to the surface.
Possible resonance from solar and/or earth magnetic activity inducing sounds.
