|
|
|
|
Mud volcano
|
| |
|
| |
- Note: See the volcano article for information on magmatic volcanoes such as Mount St. Helens or Kilauea.
- The geothermal phenomena known as "mud volcanoes" are often not true volcanoes. See mudpot for further information.
The term mud volcano or mud dome is used to refer to formations created by geo-excreted liquids and gases, although there are several different processes which may cause such activity.
Discussion
Ask a question about 'Mud volcano' Start a new discussion about 'Mud volcano' Answer questions from other users |
Encyclopedia
- Note: See the volcano article for information on magmatic volcanoes such as Mount St. Helens or Kilauea.
- The geothermal phenomena known as "mud volcanoes" are often not true volcanoes. See mudpot for further information.
The term mud volcano or mud dome is used to refer to formations created by geo-excreted liquids and gases, although there are several different processes which may cause such activity. Temperatures are much cooler than igneous processes. 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.
Details
A mud volcano may be the result of a piercement structure 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; hydrocarbon gases are often erupted. They are also often associated with lava volcanoes; in the case of such close proximity, mud volcanoes emit incombustible gases including helium, whereas lone mud volcanoes are more likely to emit methane.
In Azerbaijan, eruptions are driven from a deep mud reservoir which is connected to the surface even during dormant periods, when seeping water still shows a deep origin. Seeps have temperatures up to 2–3 °C above the ambient temperature.
Approximately 1,100 mud volcanoes 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.
Mud volcanoes are frequently associated with earthquake zones. Many scientists suggest monitoring gas emissions and activity of mud volcanoes, because they can be suitable to predict strong earthquakes.
Features
- Gryphon: steep-sided cone shorter than 3 meters that extrudes mud
- Mud cone: high cone shorter than 10 meters that extrudes mud and rock fragments
- Scoria cone: cone formed by heating of mud deposits during fires
- Salse: water-dominated pools with gas seeps
- Spring: water-dominated outlets smaller than 0.5 meters
- Mud shield and many other kinds of features
Emissions
First order estimates of mud volcano emissions have been recently made (1 Tg = 1 million metric tonnes).
- 2002: L.I. Dimitrov estimated that 10.2–12.6 Tg/yr of methane is released from onshore and shallow offshore mud volcanoes.
- 2002: Etiope and Klusman estimated at least 1–2 and as much as 10–20 Tg/yr of methane may be emitted from onshore mud volcanoes.
- 2003: Etiope, in an 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."
- 2003: analysis by Milkov et al suggests that the global gas flux may be as high as 33 Tg/yr (15.9 Tg/yr during quiescent periods plus 17.1 Tg/yr during eruptions). Six teragrams per year of greenhouse gases are from onshore and shallow offshore mud volcanoes. Deep-water sources may emit 27 Tg/yr. Total may be 9% of fossil CH4 missing in the modern atmospheric CH4 budget, and 12% in the preindustrial budget.
- 2003: Alexei Milkov estimated approximately 30.5 Tg/yr of gases (mainly methane and CO2) may escape from mud volcanoes to the atmosphere and the ocean.
- 2003: Achim J. Kopf estimated 1.97×1011 to 1.23×1014 m³ of methane is released by all mud volcanoes per year, of which 4.66×107 to 3.28×1011 m³ is from surface volcanoes. That converts to 141–88,000 Tg/yr from all mud volcanoes, of which 0.033–235 Tg is from surface volcanoes.
Locations
Europe and Asia
Mud volcanoes are generally few in Europe, but dozens can be found on the Taman Peninsula of Russia and the Kerch Peninsula of southeastern Ukraine.
In Italy, they are common in the northern front of the Apennines and in Sicily.
Another relatively accessible place where mud volcanoes can be found in Europe are the Berca Mud Volcanoes near Berca in Buzau County, Romania, close to the Carpathian Mountains.
Many mud volcanoes exist on the shores of the Black Sea and Caspian Sea. Tectonic forces and large sedimentary deposits around the latter 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 (see below). Iran and Pakistan also possess mud volcanoes in the Makran range of mountains in the south of the two countries.
China has a number of mud volcanoes in Xinjiang province. There are also mud volcanoes at the Arakan Coast in Myanmar. There are two active mud volcanoes in South Taiwan, and several inactive ones.
The island of Baratang, part of the Great Andaman archipelago in the Andaman Islands, Indian Ocean, has several sites of mud volcanic activity. There was a significant eruption event in 2003.
A drilling accident offshore of Brunei in 1979 caused a mud volcano which took 20 relief wells and nearly 30 years to stop the eruption.
Drilling or an earthquake may have resulted in the Sidoarjo mud flow on May 29, 2006, in the Porong subdistrict of East Java province, Indonesia. The mud covered about 440 hectares, or , and inundated four villages, homes, roads, rice fields, and factories and displaced about 24,000 people, killing 14. The gas exploration company was operated by PT Lapindo Brantas. In 2008, it was termed the world's largest mud volcano and is beginning to show signs of catastrophic collapse, according to geologists who have been monitoring it and the surrounding area. A catastrophic collapse could sag the vent and surrounding area by up to 150 meters in the next decade. In March 2008, the scientists observed drops of up to 3 meters in one night. Most of the subsidence in the area around the volcano is more gradual, at around 0.1 cm per day. Now named Lusi, the mud volcano appears to be a hydrocarbon/hydrothermal hybrid. Lusi is actually a contraction of Lumpur Sidoarjo, where lumpur is the Indonesian word for "mud".
Azerbaijan
It is estimated that 300 of the planet's estimated 700 mud volcanoes sit in Eastern Azerbaijan and the Caspian Sea. In 2001, one mud volcano 15 kilometers from Baku made world headlines when it suddenly started spewing flames 15 meters high.
North and South America
Mud volcanoes of the North American continent include:
- Shrub and Klawasi mud volcanoes in the Copper River basin by the Wrangell Mountains, Alaska, USA. Emissions are mostly CO2 and nitrogen; the volcanoes are associated with magmatic processes.
- An unnamed mud volcano 30 m high and with a top about 100 m wide, 24 km off Redondo Beach, California, and 800 m under the surface of the Pacific Ocean.
- A field of small (<3 meters) mud volcanoes in the Salton Sea geothermal area near the town of Niland, California. Emissions are mostly CO2.
- Smooth Ridge mud volcano in 1,000 m of water near Monterey Canyon, California.
- Kaglulik mud volcano, 43 m under the surface of the Beaufort Sea, near the northern boundary of Alaska and Canada. Petroleum deposits are believed to exist in the area.
- Maquinna mud volcano, located 16-18 kilometers west of Vancouver Island, British Columbia, Canada.
- There are many mud volcanoes in Trinidad and Tobago in the Caribbean, near oil reserves in southern parts of the island of Trinidad. As of August 15, 2007, the mud volcano titled the Moruga Bouffle was said to being spitting up methane gas which shows signs that it is definitely active. There are also several other mud volcanoes in the tropical island which include:
- the Devils Woodyard mud volcano near Hindustan ** the Moruga Bouffe mud volcano near Moruga
- the Piparo mud volcano
- the Chatham mud volcano located underwater in the Columbus Channel; this mud volcano periodically produces a short-lived island.
- Venezuela. The eastern part of Venezuela contains several mud volcanoes, all of them, as in Trinidad, having an origin related to oil deposits. The image shows the Volcán de lodo de Yagrumito, about 6 km from Maturín, Venezuela. Its mud contains, water, biogenic gas, a certain amount of hydrocarbons and an important quantity of salt. Cows from the savanna often gather around to lick the dried mud for its salt content, which is an integral part of their diet needed to produce milk.
- Colombia. Volcan El Totumo , which marks the division between Bolivar and Atlantico in Colombia. This volcano is approximately high and can accommodate 10 to 15 people on its crater; many tourists and locals visit this volcano due to the medicinal benefits of the mud; the volcano is located next to a cienaga, or lake. This volcano is currently under a legal fight between the Bolivar and Atlantico Departamentos because of its tourist value.
Yellowstone's "Mud Volcano"
The name of Yellowstone National Park's "Mud Volcano" feature and the surrounding area is misleading; it consists of hot springs, mud pots and fumaroles, rather than a true mud volcano. Depending upon the precise definition of the term mud volcano, the Yellowstone formation could be considered a hydrothermal mud volcano cluster. The feature is much less active than in its first recorded description, although the area is quite dynamic. Yellowstone is an active geothermal area with a magma chamber near the surface, and active gases are chiefly steam, carbon dioxide, and hydrogen sulfide.
The mud volcano in Yellowstone was previously a mound, until suddenly, it tore itself apart into the formation seen today.
See also
External links
-
- Azerbaijan Academy Of Sciences (in English)
- - USGS, June 2003
- - October 29, 2001, BBC report
-
-
- - U.S. Geological Survey Water-Resources Investigations Report 00-4207
-
-
- , August 2006
-
|
| |
|
|
