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 less than a meter high and 1 or 2 meters across, to 700 meters tall 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.

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 metres
  • Mud shield

    Emissions

Deep Sea Mud Volcanoes
Mud volcanoes are regularly found along the subsurface seafloor, they are primarily responsible for releasing methane into the water column along with other gases and fluids. The high pressure and low temperature associated with the bottom of the seafloor can be the predominant cause of why gases and fluids get trapped that are rising upward; this is a result of methane oversaturation. The total methane emission of offshore mud volcanoes is about 27 Tg per year. This estimate does come with uncertainties, such as the total number of mud volcanoes and their release of methane into the atmosphere/water column is unknown.
Surface Mud Volcanoes
Most liquid and solid material is released during eruptions, but seeps occur during dormant periods. The chemical composition of mud volcanoes is almost entirely methane and hydrocarbons found within the mud and the shale from the mud volcanoes. The emissions from mud volcanoes can be entirely dependent on its location, mud volcanoes from NW China are more enriched with methane and have lower concentrations of propane and ethane. The origin of the gas is most likely from below 5000m in the Earth's crust.
The mud is rich in halite. The overall chemical composition of mud volcanoes is similar to normal magma concentrations. The content of the mud volcano from Kampun Meritam, Limbang are 59.51 weight percent SiO2, 0.055 wt.% MnO, and 1.84 wt.% MgO.
First-order estimates of mud volcano emissions have been made.
  • 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, seepage from seafloor, microseepage in hydrocarbon-prone areas and geothermal sources, 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. 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 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

Dozens of mud volcanoes are located on the Taman Peninsula of Russia and the Kerch Peninsula of Crimea, Ukraine along with the south-western portion of Bulgaria near Rupite. In Italy, they are located in Emilia-Romagna, in the northern front of the Apennines as well as the southern part, and in Sicily. On 24 August 2013, a mud volcano appeared in the center of the via Coccia di Morto roundabout in Fiumicino near Rome.
Mud volcanoes are located in the Berca Mud Volcanoes near Berca in Buzău County, Romania, close to the Carpathian Mountains. They were declared a natural monument in 1924.

Asia

Central Asia, The Caucasus, and The Caspian Sea

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.

Georgia

There are mud volcanoes in Georgia, such as the one at Akhtala.

Turkmenistan

is home to numerous mud volcanoes, mainly in the western part of the country including Cheleken Peninsula, which borders the Caspian Sea.

Iran and Pakistan (Makran Mountain Range)

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 on the way to Hinglaj and is a Hindu pilgrim site.

Azerbaijan

and its Caspian coastline are home to nearly 400 mud volcanoes, more than half the total throughout the continents. Most mud volcanoes in Azerbaijan are active; some are protected by the Azerbaijan Ministry of Ecology and Natural Resources, and the admission of people, for security reasons, is prohibited. In 2001, one mud volcano from Baku made world headlines when it started ejecting flames high.
In Azerbaijan, eruptions are driven from a deep mud reservoir which is connected to the surface even during dormant periods, when seeping water shows a deep origin. Seeps have temperatures that are generally above ambient ground temperature by –.
On 4 July 2021, a mud volcano eruption on Dashli Island in the Caspian Sea, near an oil platform off the coast of Azerbaijan, caused a massive explosion and fireball, which was seen across the region, including from the capital Baku, which is to the north. The flames towered into the air. There were no reports of injuries or damage to any oil platforms. The last previous volcanic eruption on the island was recorded in 1945 and the preceding one in 1920.

India

Extensive mud volcanism occurs on the Andaman accretionary prism, located at the Andaman Islands in the Indian Ocean.

Indonesia

Mud volcanism is a common phenomenon 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 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 29 May 2006. The mud covered about 440 hectares, , 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 6.4 magnitude Yogyakarta earthquake of 27 May 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 forecast 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 geoscientists 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 mud pots varying in temperature are found.
In Grobogan, Bledug Kuwu mud volcano erupts at regular intervals, about every 2 or 3 minutes.