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A Volcano Beneath The Snow PDF Free Download

Three summit craters have been active in the last 10,000 years. The active vent is now beneath the crater lake of South Crater. The crater lake contains warm, acidic water that is fed by snow melt. Ruapehu is a stratovolcano (composite cone volcano) made of successive layers of andesite lava and ash deposits. The mountain is surrounded by a. Lassen (or Lassen Peak) volcano in northern California is located at the southern end of the Cascade Range. Helens, it is the only volcano in the contiguous US that erupted in the 20th century. Lassen's summit complex is a lava dome that rises 2,000 feet (610 m) above the surrounding terrain and has a volume of half a cubic mile. PPT – 2010 Dynamic Planet: Earthquakes and Volcanoes PowerPoint presentation free to download - id: 1fb449-ZDc1Z The Adobe Flash plugin is needed to view this content Get the plugin now.

Scheme of subglacial volcano eruption
Ice covered Katla volcano, Iceland, in 2011, with hydrothermally or eruption caused ice cauldrons. The volcanic ash is from the 2010 eruptions at nearby Eyjafjallajökull volcano.
Small subglacial eruption at Mount Redoubt, Alaska
Explosive subglacial eruption at Eyjafjallajökull, Iceland, in 2010
45.000 m3/sec jökulhlaup on Skeiðarársandur, Iceland, in 1996 in connection with a eruption in Grímsvötn
Degassing at a subglacial volcanic fissure, Makushin volcano, Alaska
Degassing at the subglacial Mount Erebus volcano, Antarctica
Mixed subglacial fissure eruption at Mount Veniaminof, Alaska

A subglacial volcano, also known as a glaciovolcano, is a volcanic form produced by subglacial eruptions or eruptions beneath the surface of a glacier or ice sheet which is then melted into a lake by the rising lava. Today they are most common in Iceland and Antarctica; older formations of this type are found also in British Columbia and Yukon Territory, Canada.

During the eruption, the heat of the lava from the subglacial volcano melts the overlying ice. The water quickly cools the lava, resulting in pillow lava shapes similar to those of underwater volcanoes. When the pillow lavas break off and roll down the volcano slopes, pillow breccia, tuff breccia, and hyaloclastite form. The meltwater may be released from below the ice as happened in Iceland in 1996 when the Grímsvötn caldera erupted, melting 3 km3 of ice and giving rise to a large glacial lake outburst flood.

The shape of subglacial volcanoes tends to be quite characteristic and unusual, with a flattened top and steep sides supported against collapse by the pressure of the surrounding ice and meltwater. If the volcano eventually melts completely through the ice layer, then horizontal lava flows are deposited, and the top of the volcano assumes a nearly level form. However, if significant amounts of lava are later erupted subaerially, then the volcano may assume a more conventional shape. In Canada the volcanos have been known to form both conical and nearly level shapes.[1] The more distinctly flat-topped, steep-sided subglacial volcanoes are called tuyas, named after Tuya Butte in northern British Columbia by Canadian geologist Bill Mathews in 1947. In Iceland, such volcanoes are also known as table mountains.

Jökulhlaups[edit]

Subglacial eruptions often cause jökulhlaups or great floods of water. In November 1996 the Grímsvötn Volcano beneath the Vatnajökull ice sheet erupted and caused a Jökulhlaup that affected more than 750 km2 (290 sq mi) and destroyed or severely damaged several bridges.[2] During the ice ages, such floods from Lake Missoula were estimated to have discharges exceeding 17 × 106 m³/s (4.5 × 109 gal/s) and covered a third of eastern Washington state. Sonia Esperanca, program director in the National Science Foundation commented on the danger of subglacial volcanoes: 'When an ice-covered volcano erupts, the interplay among molten magma, ice and meltwater can have catastrophic results.'[3]

Antarctica eruption[edit]

In January, 2008, the British Antarctic Survey (Bas) scientists led by Hugh Corr and David Vaughan, reported (in the journal Nature Geoscience) that 2,200 years ago, a volcano erupted under the Antarctica ice sheet (based on airborne survey with radar images). The biggest eruption in the last 10,000 years, the volcanic ash was found deposited on the ice surface under the Hudson Mountains, close to Pine Island Glacier.[4]

On Mars[edit]

Many scientists believe that liquid water exists many kilometers below the surface of Mars, but at this point in time it is impossible to drill to those depths with the rovers in existence. Meredith Payne and Jack Farmer of Arizona State University have studied images from the Viking and Mars Orbiter cameras in search of possible sub-glacial volcanoes that could carry microbes to the surface.[5]

Ice cores[edit]

It is possible to track catastrophic subglacial volcano eruptions in time with the analysis of ice cores such as the Vostok core. Subglacial volcanic eruptions are identified by layers of high concentrations of NO
3
and SO2−
4
.[6]

See also[edit]

References[edit]

Wikimedia Commons has media related to Subglacial volcanoes.
  • Volcanoes of Canada: Types of volcanoes Accessed Jan. 8, 2006
  1. ^'Volcanoes of Canada'. Geological Survey of Canada. Archived from the original on February 2, 2009. Retrieved January 19, 2009.
  2. ^http://www.accessscience.com/content.aspx?searchStr=subglacial+volcano&id=735200
  3. ^'Volcanoes Under Glaciers in Iceland, Canada and the United States'. Archived from the original on May 4, 2010. Retrieved June 1, 2010.
  4. ^Black, Richard (20 January 2008). 'Ancient Antarctic eruption noted'. BBC News. London: BBC. Archived from the original on 15 January 2009. Retrieved 22 October 2011.
  5. ^'Subglacial Volcanoes On Mars'. Archived from the original on 2011-06-06.
  6. ^'International Glaciological Society'(PDF). International Glaciological Society (IGS). Archived(PDF) from the original on 2018-05-04.
Retrieved from 'https://en.wikipedia.org/w/index.php?title=Subglacial_volcano&oldid=991264574'


U.S. Geological Survey Fact Sheet 172-96
Online Version 2.0

Invisible CO2 Gas Killing Trees at Mammoth Mountain, California

Since 1980, scientists have monitored geologic unrest in Long Valley Caldera and at adjacent Mammoth Mountain, California. After a persistent swarm of earthquakes beneath Mammoth Mountain in 1989, geologists discovered that large volumes of carbon dioxide (CO2 ) gas were seeping from beneath this volcano. This gas is killing trees on the mountain and also can be a danger to people. The U.S. Geological Survey (USGS) continues to study the CO2 emissions to help protect the public from this invisible potential hazard.

Mammoth Mountain is a young volcano on the southwest rim of Long Valley Caldera, a large volcanic depression in eastern California. The Long Valley area, well known for its superb skiing, hiking, and camping, has been volcanically active for about 4 million years. The most recent volcanic eruptions in the region occurred about 200 years ago, and earthquakes frequently shake the area. Because of this, the U.S. Geological Survey (USGS) operates an extensive network of instruments to monitor the continuing unrest in the Long Valley area.

Numerous small earthquakes occurred beneath Mammoth Mountain from May to November 1989. Data collected from monitoring instruments during those months indicated that a small body of magma (molten rock) was rising through a fissure beneath the mountain. During the next year, U.S. Forest Service rangers noticed areas of dead and dying trees on the mountain. After drought and insect infestations were eliminated as causes, a geologic explanation was suspected. USGS scientists then made measurements and discovered that the roots of the trees were being killed by exceptionally high concentrations of carbon dioxide (CO2) gas in the soil. Today, areas of dead and dying trees at Mammoth Mountain total more than 100 acres. The town of Mammoth Lakes, just east of this volcano, has not been affected.


Mammoth Mountain, a young volcano in eastern California, sits on the southwest rim of Long Valley Caldera. In 1994, scientists detected high concentrations of CO2 gas in the soil on Mammoth Mountain. This invisible gas, seeping from beneath the volcano, is killing trees on the sides of the mountain and can pose a threat to humans. Recent measurements indicate that the total rate of CO2 gas emission at Mammoth Mountain is close to 300 tons per day. In this photo, large areas of dead and dying trees are visible near Horseshoe Lake, on the southeast flank of Mammoth Mountain. (Copyrighted photo courtesy of John D. Rogie.)

Areas of dead and dying trees at Mammoth Mountain volcano total more than 100 acres. In 1990, the year after a persistent swarm of small earthquakes occurred beneath the volcano, U.S. Forest Service rangers first noticed areas of tree kill. When U.S. Geological Survey scientists investigated, they discovered that the trees are being killed by high concentrations of CO2 gas in the soil. The seepage of CO2 gas from below Mammoth Mountain and the continued occurrence of local earthquakes are signs of the ongoing geologic unrest in the area. The upper part of the 11,053-foot-high volcano (above 9,500 feet) is shown in darker shades of green (map, top right).

Although leaves of plants produce oxygen (O2) from CO2 during photosynthesis, their roots need to absorb O2 directly. The high CO2 concentrations in the soil on Mammoth Mountain are killing trees by denying their roots O2 and by interfering with nutrient uptake. In the areas of tree kill, CO2 makes up about 20 to 95% of the gas content of the soil; soil gas normally contains 1% or less CO2.

When CO2 from soil leaves the ground, it normally mixes with the air and dissipates rapidly. CO2 is heavier than air, however, and it can collect at high concentrations in the lower parts of depressions and enclosures, posing a potential danger to people. Breathing air with more than 30% CO2 can very quickly cause unconsciousness and death. Therefore, poorly ventilated areas above and below ground can be dangerous in areas of CO2 seepage. Where thick snowpacks accumulate in winter, the CO2 can be trapped within and beneath the snow. Dangerous levels of CO2 have been measured in pits dug in the snowpack in tree-kill areas on Mammoth Mountain, and snow-cave camping in such areas is not advised.


CO2 gas seeping from the ground at Mammoth Mountain is likely derived from magma (molten rock) beneath the volcano. In 1989, rising magma may have opened cracks, allowing large amounts of trapped CO2 gas to leak upward along faults. High concentrations of CO2 in soil can kill the roots of trees. CO2 gas is heavier than air, and when it leaks from the soil, it can collect in snowbanks, depressions, and poorly ventilated enclosures, such as cabins and tents, posing a potential danger to people.

In 1989–90, trees in this area on the south side of Mammoth Mountain volcano began dying from high concentrations of CO2 gas in the soil. Although leaves of plants produce oxygen (O2) from CO2 during photosynthesis, their roots need to absorb O2 directly. High CO2 concentrations in the soil kill plants by denying their roots O2 and by interfering with nutrient uptake. In the areas of tree kill at Mammoth Mountain, CO2 makes up about 20 to 95% of the gas content of the soil. Inset (right photo) shows scientists measuring soil gas in this area.

Geologists have detected CO2 emissions, like those at Mammoth Mountain, on the flanks of other volcanoes, including Kilauea in Hawaii and Mount Etna in Sicily. Measuring the total rate of CO2 gas emissions on the flanks of volcanoes or within calderas is difficult and labor intensive and is commonly done using portable infrared CO2 detectors.

A volcano beneath the snow pdf free download windows 7

Recent measurements at Mammoth Mountain indicate that the total rate of CO2 gas emission is close to 300 tons per day. This value varies on both short (days to weeks) and long (months to years) time scales because of changes in atmospheric conditions and in the rate at which gas is being released from beneath the volcano.

Past eruptions at Mammoth Mountain, such as the phreatic (steam blast) eruptions that occurred about 700 years ago on the volcano’s north flank, may have been accompanied by CO2 emissions. Scientists think that the current episode of high CO2 emissions is the first such activity on the mountain for at least 250 years because the oldest trees in the active tree-kill areas are about that age. Carbon-isotopic analyses of the annual growth rings in trees near the margins of the tree-kill areas imply that the gas-emission rate reached a peak in 1991, subsequently declined, and then has been relatively stable since about 1996.

CO2 and other volcanic gases, like helium, seeping from Mammoth Mountain appear to be leaking from a large reservoir of gas supplied by repeated intrusions of magma. Tree-ring evidence from near springs on the mountain’s flanks shows that some CO2 gas was leaking before 1989 and dissolving in the ground-water system. It is likely that the latest intrusion of magma (in 1989) opened deep fractures, increasing the rate of gas seepage.

The continuing occurrence of small earthquakes and CO2 seepage beneath Mammoth Mountain are only two of the many signs of volcanic unrest in the area. Earthquakes and ground uplift are also occurring within the central part of Long Valley Caldera, only a few miles east of Mammoth Mountain, and the Mono-Inyo Craters volcanic chain to the north has had small volcanic eruptions every few hundred years for the past 4,000 years.

Scientists with the USGS Volcano Hazards Program are closely monitoring CO2 emissions and other geologic hazards at Mammoth Mountain. The work of these scientists is only part of the USGS Volcano Hazards Program’s ongoing efforts to protect people’s lives and property in all of the volcanic regions of the United States, including the Pacific Northwest, Alaska, Hawaii, and Arizona.

Michael L. Sorey, Christopher D. Farrar, Terrance M. Gerlach, Kenneth A. McGee, William C. Evans, Elizabeth M. Colvard, David P. Hill, Roy A. Bailey, John D. Rogie, James W. Hendley II, and Peter H. Stauffer

Graphic design by
Susan Mayfield and Sara Boore
Banner design by Bobbie Myers

COOPERATING ORGANIZATIONS
Mammoth Mountain Ski Area
Town of Mammoth Lakes
U.S. Department of Agriculture, Forest Service
Pennsylvania State University

For more information contact:

Earthquake Information Hotline (650) 329–4085
U.S. Geological Survey, Mail Stop 977
345 Middlefield Road, Menlo Park, CA 94025

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URL of this page: https://pubs.usgs.gov/fs/fs172-96/
Maintained by: Michael Diggles
Created: June 20, 2001 (cad)
Last modified: July 9, 2007 (mfd)