Skyquake

Names (according to area) are: • Bangladesh: Barisal guns • France: "bombes de mer", "canons de mer". • Indonesia: dentuman (lit: "clatter") or suara tembakan meriam (lit: "the sound of cannon fire"). • Italy: "brontidi", "marina", "balza", "lagoni", "bomba", "rombo", "boato", "bonnito", "mugghio", "baturlio", "tromba", "rufa". • Japan: "uminari" (literally, "cries from the sea") • Netherlands and Belgium: "mistpoeffers", "zeepoeffers", "zeedoffers", "mistbommen", "gonzen", "balken", "onderaardse geruchten". • Philippines and Iran: "retumbos" • United States: "Guns of the Seneca" around Seneca Lake and Cayuga Lake, Seneca guns in the Southeast US • Latin America and Spain: "cielomoto" • Canada: "seefahrts" • elsewhere: "fog guns", "mistpouffers", "waterguns" 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.” 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 and Passamaquoddy Bay, New Brunswick, Canada; Lough Neagh in Northern Ireland; Scotland; 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, 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 explanations have been: • Moderate-sized meteors causing sonic booms as they strike the lower atmosphere. • Avalanches, either natural or human-caused (for avalanche control). • Weather: Distant thunder, or loud sounds from wind damage. • Atmospheric ducting of distant thunder or other loud sounds from far off. • Secondary atmospheric waves from plasma impacts of solar CMEs. 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 40 percent of the speed of light. 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. • 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. == See also ==