Mud volcano

A mud volcano or mud dome is a landform created by the eruption of mud or slurries, water and gases. Several geological processes may cause the formation of mud volcanoes. Mud volcanoes are not true igneous volcanoes as they do not produce lava and are not necessarily driven by magmatic activity. Mud volcanoes may range in size from merely 1 or 2 meters high and 1 or 2 meters wide, to 700 meters high and 10 kilometers wide. Smaller mud exudations are sometimes referred to as mud-pots.
The mud produced by mud volcanoes is mostly formed as hot water, which has been heated deep below the Earth's surface, begins to mix and blend with subterranean mineral deposits, thus creating the mud slurry exudate. This material is then forced upwards through a geological fault or fissure due to local subterranean pressure imbalances. Mud volcanoes are associated with subduction zones and about 1100 have been identified on or near land. The temperature of any given active mud volcano generally remains fairly steady and is much lower than the typical temperatures found in igneous volcanoes. Mud volcano temperatures can range from near to occasionally , some being used as popular "mud baths".
About 86% of the gas released from these structures is methane, with much less carbon dioxide and nitrogen emitted. Ejected materials are most often a slurry of fine solids suspended in water that may contain a mixture of salts, acids and various hydrocarbons.
Possible mud volcanoes have been identified on Mars.
Details.
A mud volcano may be the result of a piercement structure created by a pressurized mud diapir that breaches the Earth's surface or ocean bottom. Their temperatures may be as low as the freezing point of the 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.
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.
Emissions.
Most liquid and solid material is released during eruptions, but seeps occur during dormant periods.
The mud is rich in halite (rock salt).
First-order estimates of mud volcano emissions have been made (1 Tg = 1 million metric tonnes).
Locations.
Europe.
Dozens of mud volcanoes can be found on the Taman Peninsula of Russia and the Kerch Peninsula of Crimea along with the south-western portion of Bulgaria near Rupite. In Italy, they are common in the northern front of the Apennines and in Sicily. On August 24, 2013, a mud volcano appeared in the centre of the via Coccia di Morto roundabout in Fiumicino near Rome.
Mud volcanoes can be found in the Berca Mud Volcanoes near Berca in Buzău County, Romania, close to the Carpathian Mountains.
Asia.
Indonesia.
Mud volcanism is a common phenomena in Indonesia with dozens of structures present onshore and offshore.
The Indonesian Lusi mud eruption is a hybrid mud volcano, driven by pressure from steam and gas from a nearby (igneous) volcanic system, and from natural gas. Geochemical, petrography and geophysical results reveal that it is a hydrothermal system connected at depth with the neighboring Arjuno-Welirang volcanic complex.
Drilling or an earthquake in the Porong subdistrict of East Java province, Indonesia, may have resulted in the Sidoarjo mud flow on May 29, 2006. The mud covered about 440 hectares, (2.73 mi2), and inundated four villages, homes, roads, rice fields, and factories, displacing about 24,000 people and killing 14. The gas exploration company involved was operated by PT Lapindo Brantas and the earthquake that may have triggered the mud volcano was the 6.3 magnitude Yogyakarta earthquake of May 27, 2006. According to geologists who have been monitoring Lusi and the surrounding area, the system is beginning to show signs of catastrophic collapse. It was forecasted that the region could sag the vent and surrounding area by up to in the next decade. In March 2008, the scientists observed drops of up to in one night. Most of the subsidence in the area around the volcano is more gradual, at around per day. A study by a group of Indonesian geo-scientists led by Bambang Istadi predicted the area affected by the mudflow over a ten-year period. More recent studies carried out in 2011 predict that the mud will flow for another 20 years, or even longer. Now named Lusi – a contraction of "Lumpur Sidoarjo", where "lumpur" is the Indonesian word for "mud" – the eruption represent an active hybrid system.
In the Suwoh depression in Lampung, dozens of mud cones and mudpots varying in temperature are found.
Central Asia.
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 high occur in Azerbaijan, with large eruptions sometimes producing flames of similar scale. There are mud volcanoes in Georgia, such as the one at Akhtala.
Iran and Pakistan possess mud volcanoes in the Makran range of mountains in the south of the two countries. A large mud volcano is located in Balochistan, Pakistan. It is known as "Baba Chandrakup" (literally Father Moonwell) on the way to Hinglaj and is a Hindu pilgrim site.
India.
Extensive mud volcanism on the Andaman accretionary prism occurs above a complex network of faults and is caused by the convergence of the Indian plate and the Burmese microplate. The mud matrix ejected from these mud volcanoes is composed of smectite–illite–kaolinite–chlorite–plagioclase–quartz–calcite assemblage derived both from sediments and altered oceanic crust and originates from a deep-burial diagenetic environment. The modes of δ13C distributions for methane (>−42‰), ethane (>−27‰) and CO2 (b−3‰) gases emitted by these mud volcanoes indicate their thermogenic origin, with TOC and N of associated mud suggesting marine organic matter as the source. The mud water is much fresher (Cl− = 45 to 135 mM) than seawater and its δ18O (−0.2 to 2.6‰)and δD (−24 to −14‰) isotopic compositions fall well below the global meteoric water line. From their trace element contents and stable isotopic compositions it is inferred that the mud water is a mixture of sediment pore water (ancient seawater) and water released from dehydration of clay minerals. The 87Sr/86Sr of mud water (~0.7071) confirms the above inference and points out that altered oceanic crust plays a significant role in controlling the chemistry of water. The formation temperatures of mud ejecta, derived from mineralogical (smectite/illite), chemical (K+/Na+) and isotopic (δD/δ18O) geothermometers, lie in the range of 50 °C to 120 °C — which corresponds to a depth zone of 2 to 6 km within the Andaman forearc. It is believed that the mud volcano ejecta originate at the plate-boundary décollement zone, from the sediments and altered oceanic crust of the subducting Indian plate.
Iran.
There are many mud volcanoes in Iran: in particular, in the provinces of Golestan, Hormozgan, and Sistan and Baluchestan, where Pirgel is located.
Pakistan.
In Pakistan there are more than 80 active mud volcanoes in Balochistan province; there are about 10 locations with clusters of mud volcanoes. In the west, in Gwadar District, the mud volcanoes are very small and mostly sit in the south of Jabal-e-Mehdi toward Sur Bandar. Many more are in the northeast of Ormara. The remainder are in Lasbela District and are scattered between south of Gorangatti on Koh Hinglaj to Koh Kuk in the North of Miani Hor in the Hangol Valley. In this region, the heights of mud volcanoes range between . The most famous is Chandragup. The biggest crater found at 25°33'13.63"N. 65°44'09.66"E is about in diameter. Most mud volcanoes in this region are in out-of-reach areas having very difficult terrain. Dormant mud volcanoes stand like columns of mud in many other areas.
Philippines.
In the Turtle Islands, in the province of Tawi-Tawi, the southwestern edge of the Philippines bordering Malaysia, presence of mud volcanoes are evident on three of the islands – Lihiman, Great Bakkungan and Boan Islands. The northeastern part of Lihiman Island is distinguished for having a more violent kind of mud extrusions mixed with large pieces of rocks, creating a 20-m (66-ft) wide crater on that hilly part of the island. Such extrusions are reported to be accompanied by mild earthquakes and evidence of extruded materials can be found high in the surrounding trees. Submarine mud extrusions off the island have been observed by local residents.
Mariana Forearc.
There are 10 active mud volcanoes in the Izu–Bonin–Mariana_Arc which can be found along a north to south trend, parallel to the Mariana trench. The material erupted at these mud volcanoes consists primarily of blue and green serpentinite mud which contains fresh and serpentinized peridotite material from the subduction channel. Serpentinite mud is formed as fluid from the down going Pacific plate is released via prehnite-pumpellyite dehydration, greenschist alteration, and blueschist dehydration. This fluid interacts with mafic and ultramafic rocks in the down going Pacific plate and overriding Philippine plate, resulting in the formation of serpentinite mud. All of these mud volcanoes are associated with faults, indicating that the faults act as conduits for the serpentine mud to migrate from the subduction channel to the surface. These mud volcanoes are large features on the forearc, the largest of which has a diameter of ~50 km and is over 2 km high.
North America.
Mud volcanoes of the North American continent include:
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.
However, there are mud volcanoes and mud geysers elsewhere in Yellowstone. One, the "Vertically Gifted Cyclic Mud Pot" sometimes acts as a geyser, throwing mud up to 30 feet high.
The mud volcano in Yellowstone was previously a mound until a thermal explosion in the 1800s ripped it apart.
South America.
Venezuela.
The eastern part of Venezuela contains several mud volcanoes (or mud domes), all of them having an origin related to oil deposits. The mud of from Maturín, contains water, biogenic gas, hydrocarbons and an important quantity of salt. Cattle from the savanna often gather around to lick the dried mud for its salt content.
Colombia.
Volcan El Totumo, which marks the division between Bolívar and Atlantico in Colombia. This volcano is approximately high and can accommodate 10 to 15 people in its crater; many tourists and locals visit this volcano due to the alleged medicinal benefits of the mud; it is next to a "cienaga", or lake. This volcano is under legal dispute between the Bolívar and Atlántico Departamentos because of its tourist value.