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Mud Volcano - Note:See the volcano article for information on magmatic volcanoes such as Mount St. Helens or Kilauea.
The term mud volcano is used to refer to formations created by geologically excreted liquids and gases, although there are several different processes which may cause such activity. The largest structures are 10 km in diameter and reach 700 metres in height. About 86% of released gases are methane, with much less carbon dioxide and nitrogen emitted. Ejected materials often are a slurry of fine solids suspended in liquids which may include water (frequently acidic or salty) and hydrocarbon fluids. Approximately 1,100 have been identified on land and in shallow water. It has been estimated that well over 10,000 may exist on continental slopes and abyssal plains. Tectonic forces and large sedimentary deposits around the Caspian Sea have created several fields of mud volcanoes, many of them emitting methane and other hydrocarbons. Features over 200 meters high exist in Azerbaijan, with large eruptions sometimes producing flames of similar scale. A mud volcano may be created by a pressurized mud diapir which breaches the Earth's surface or ocean bottom. Temperatures may be as low as the freezing point of ejected materials, particularly when venting is associated with the creation of hydrocarbon clathrate hydrate deposits. Mud volcanoes are often associated with petroleum deposits and tectonic subduction zones and orogenic belts. Emissions First order estimates of mud volcano emissions have been recently made. Achim J. Koph in 2003 estimated 1.97 × 1014 to 1.22 × 1022 Tg of methane has been released by all mud volcanoes during the past 1,000 years, of which 4.66 × 1010 to 3.28 × 1014 g is from surface volcanoes. http://springerlink.metapress.com/app/home/contribution.asp?wasp=46wayjuxql0qud6vkyvm&referrer=parent&backto=issue,11,13;journal,9,32;linkingpublicationresults,1:103695,1 How much of this powerful greenhouse gas reaches the atmosphere from submarine volcanoes is not known. L.I. Dimitrov in 2002 estimated that 10.2-12.6 Tg/yr of methane is released from onshore and shallow offshore mud volcanoes. Etiope and Klusman in 2002 estimated at least 1-2 and as much as 10-20 Tg/yr may be emitted from onshore mud volcanoes. Alexei Milkov estimated as much as 30.5 Tg/yr of gases (mainly methane and CO2) may escape from mud volcanoes to the atmosphere and the ocean. http://aapg.confex.com/aapg/sl2003/techprogram/paper_77807.htm In a conservative estimate based on 120 mud volcanoes: - "The emission results to be conservatively between 5 and 9 Tg/yr, that is 3-6 % of the natural methane sources officially considered in the atmospheric methane budget. The total geologic source, including MVs (this work), seepage from seafloor (Kvenvolden et al., 2001), microseepage in hydrocarbon-prone areas and geothermal sources (Etiope and Klusman, 2002), would amount to 35-45 Tg/yr." http://gsa.confex.com/gsa/inqu/finalprogram/abstract_53365.htm
North American mud volcanoes Mud volcanoes of the north american continent include Yellowstone's Mud Volcano The name of Yellowstone National Park's Mud Volcano area is misleading; it consists of mud pots and fumaroles rather than a true mud volcano. Yellowstone is an active geothermal area with a magma chamber near the surface, and active gases tend to be steam, carbon dioxide, and hydrogen sulfide.http://volcanoes.usgs.gov/Products/Pglossary/MudVolcano.html See also Web sites
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