A skyquake is a phenomenon where a loud sound is reported to originate from the sky. It often manifests as a banging, or a horn-like noise. The sound may cause noticeable vibration in the ceiling or across a particular room. Those who experience skyquakes typically do not have a clear explanation for what caused them and they are perceived as mysterious. They have been heard in several locations around the world, typically in areas close to lakes and other bodies of water. Reports of skyquakes have come from the North Sea, the Ganges, Canada, Colombia, Japan, Finland, Australia, Italy, Ireland, India, The Netherlands, Norway, Tierra del Fuego in Argentina, the United Kingdom, the United States, Mexico, Malaysia (particularly Ipoh) and Indonesia (particularly Jakarta and Java).
In 1804, they were reportedly heard during the Lewis and Clark Expedition near Great Falls. Meriwether Lewis wrote “since our arrival at the falls we have repeatedly witnessed a noise which proceeds from a direction a little to the N. of West as loud and resembling precisely the discharge of a piece of ordinance of 6 pounds at the distance of three miles.” William Clark added in his notes, “…a rumbling like Cannon at a great distance is heard to the west of us; the Cause we Can’t account.”[6]
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.[citation needed]
The terms "mistpouffers" and "Seneca guns" both originate in Seneca Lake, New York, 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. Given the long time that they have been known and reported, but with no proposal experimentally confirmed, it seems likely that they occur for more than one reason. Proposed explainations have been:
Moderate-sized meteors causing sonic booms as they strike the lower atmosphere.[8]
Gas explosions, either by ignition or sudden release of trapped deposits:
Gas escaping from vents in the Earth's surface.[citation needed]
With lakes, bio gas from decaying vegetation trapped beneath the lake bottoms suddenly bursting forth. (Plausible, since Cayuga Lake and Seneca Lake are large, deep lakes with millennia of deep deposition of organically enriched sediment.)[citation needed]
Explosive release of less volatile gases generated as limestone decay in underwater caves.[citation needed]
Underwater caves collapsing, and either the released air and/or a wave of water pressure vacuum abruptly arriving at the lake surface.
Volcanic eruptions (in places near known volcanic activity).
Military aircraft surreptitiously creating sonic booms. (This origin does not explain sounds heard before supersonic flight, but could be extended to include military cannon-fire practice.)
Earthquakes: Shallow earthquakes can generate sound waves with little ground vibration: The "booming" sound is heard only locally, near the epicenter.[8][9]
Secondary atmospheric waves from plasma impacts of solarCMEs. CMEs generate plasma shock waves in space, similar to the sonic boom caused by aircraft flying faster than the speed of sound in Earth's atmosphere. The solar wind's equivalent of a sonic boom in the Solar System plasma medium can accelerate protons up to millions of miles per minute – as much as 40percent of the speed of light.[11] This is a proven source of auroras, but has never yet been shown to be sufficiently forceful and sufficiently abrupt to cause a "boom".
Possible resonance from solar and/or Earth magnetic activity inducing sounds.[12]
Breaking waves: A line of breaking waves on a rocky shore is capable of producing booming noises at low frequencies, thereby allowing the sound to travel for longer distances.[13]
↑ T.D. LaTouche, "On the Sounds Known as Barisal Guns", Report (1890-8) of the annual meeting By British Association for the Advancement of Science, Issue 60, pp. 800.
↑ Eraldo Baldini, "Tenebrosa Romagna", Il Ponte Vecchio, 2014, p. 21.
↑ William R. Corliss, Earthquakes, Tides, Unidentified Sounds, and related phenomena (The Sourcebook Project, 1983).
↑ M.G.J.Minnaert, De Natuurkunde van 't Vrije Veld, Deel 2: Geluid, Warmte, Elektriciteit, § 48: Mistpoeffers, bladzijden 63-64.
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