Largest Single Mud Volcano in the World Discovered in Caspian Sea

Researchers Richard Davies and Simon Stewart of the School of Earth, Ocean and Planetary Sciences at Cardiff University, Sudbury on Thames, England, have identified the largest single mud volcano yet described on earth! (2005) (1)

The newly discovered mud volcano is located underwater on the bottom of the southern part of the ancient Caspian Sea in southeastern Europe and southwestern Asia. The saltwater Caspian Sea is the largest inland body of water in the world. It extends about 750 miles in a northern and southern direction and about 130 to 271 miles in an eastern and western direction. It has an area of 143,000 sq miles. Its mean depth is about 550 ft and it is deepest in the south where the new mud volcano is located. Its level varies from year to year but averages about 92 feet below sea level. The Caspian Sea is known as a terminal lake because it has no outlet; however the Volga River flows into it. It is generally believed that about 90 percent of all the world’s sturgeons swim in the Caspian Sea. Seven species or subspecies of sturgeon populate the Caspian, giving it the greatest diversity of sturgeon in the world. Sturgeon eggs (roe) are known as caviar. The Caspian Sea is also one of the major petroleum-producing areas of the world.

The diameter of the mud volcano discovered by the Davies-Stewart team is 6.2 miles and its height 4,600 feet! A mud volcano is a geologic formation created by geologically excreted liquids and gases that are cooler than hot igneous processes. Mud volcanoes are frequently located near petroleum fields.

In addition to discovering a mile-high mud volcano, Davies and Stewart located with their 3D seismic instruments an oval caldera beneath the mud volcano. The caldera measures about 5,000 feet across and 1,600 feet deep. A caldera is a large depression commonly formed by collapse of the ground following explosive eruption of a large body of stored magma. Calderas at Yellowstone National Park are associated with eruption of silicic magma as pyroclastic flows that covered large areas around and within the caldera (see also SEMP Biot #164: Yellowstone Is a Supervolcano?? at: http://www.semp.us/biots/biot_164.html; accessed January 4, 2006).

The caldera now filled by Oregon's Crater Lake was produced by an eruption that destroyed a volcano the size of Mount St. Helens and sent volcanic ash as far east as Nebraska. The Crater Lake caldera is six miles in diameter and almost 2,000 feet deep, making it the seventh deepest lake in the world and the deepest lake in the United States. Thus, it is much larger than the caldera beneath the Davies-Stewart mud volcano.
The Davies-Stewart mud-volcano discovery is important for at least four reasons. First, it advances the idea that mud volcanoes are analogous, at least in structure, to igneous caldera systems, an idea that has obvious ramifications for life on earth as hundreds of thousands of active mud volcanoes are being discovered throughout the world today. Second, mud volcanoes like the one discovered by Davies and Stewart, vent as yet unmeasured quantities of methane, a well-established greenhouse gas that affects the earth’s climate and is thought to have contributed to major extinctions of life forms on earth.

Third, the Davies-Stewart mud volcano’s plumbing architecture shows a feeder system that connects a major volcanic cone to its mud source layer some 10,000 feet below. These volcano and feeder systems have similarities to igneous centers, which also have cone-shaped edifices, calderas and downward tapering cones created during magma chamber collapse and ring-dyke intrusion. Thus, 3D seismic data employed in discovering and describing the Davies-Stewart mud volcano may shed light on the structure of poorly exposed igneous architectures. Fourth, more accurate models of mud volcano volume can help “estimate total methane emitted from these major structures into the atmosphere over geological time scales.” (p. 4)

Source:

1. Richard Davies, Simon Steward: “Emplacement of giant mud volcanoes in the South Caspian Basin: 3D seismic reflection imaging of their root zones.” Journal of the Geological Society, London, Vol. 162, 2005, pp. 1-4, Great Britain.