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Antarctic Volcanoes
[edit]Antarctic Volcanoes
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Volcanoes that occur underneath glacial ice sheets are known by the term "Glaciovolcanism", or subglacial volcanoes. An article published in 2017 claims that researchers from Edinburgh University recently discovered 91 new volcanoes below the Antarctic ice sheet, adding to the 47 volcanoes that were already known[2]. As of today, there have been 138 possible volcanoes identified in West Antarctica.[3] There is limited knowledge about West Antarctic Volcanoes due to the presence of the West Antarctic Ice Sheet, which heavily covers the West Antarctic Rift System -- a likely hub for volcanic activity. [4] Researchers find it difficult to properly identify volcanic activity due to the comprehensive ice covering.
East Antarctica is significantly larger than West Antarctica, and similarly remains widely unexplored in terms of its volcanic potential. While there are some indications that there is volcanic activity under the East Antarctic Ice Sheet, there is not a significant amount of present information on the subject.
Mount Erebus is one of the most notable cites in the study of Antarctic Volcanism, in that it is the southernmost historically active volcanic cite on the planet.[5]
Deception Island is another active Antarctic volcano. It is one of the most protected areas in the Antarctic, given its situation between the South Shetland Islands and the Antarctic Peninsula. As the most active volcano in the Antarctic peninsula, it has been studied closely since its initial discovery in 1820.
The definition of Glaciovolcanism is “the interactions of magma with ice in all its forms, including snow, firn and any meltwater.”[6] It defines a special field of volcanic that is specifically centered around ice and ice melt. This field of science is less than 100 years old, and thus continuously makes new discoveries. Glaciovolcanism is characterized by three kinds of eruptions: sub-glacial eruptions, supraglacial volcanism, and ice-marginal volcanism.[7]
The study of glaciovolcanism is vital to the understanding of ice sheet formation. It is also a valuable tool to predict volcanic hazards, such as the ash hazard following the Eyjafjallajökull eruption in Iceland.
Marie Byrd Land
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The Marie Byrd Land is an incredibly large portion of West Antarctica, consisting of the Area below the Antarctic Peninsula. The Marie Byrd land is a large formation of volcanic rock, characterized by 18 exposed and subglacial volcanoes. 16 of the 18 volcanoes are entirely covered by the antarctic ice sheet.[8] There have been no eruptions recorded from any of the volcanoes in this area, however scientists believe that some of the volcanoes may be potentially active.
The Marie Byrd land has one of the harshest climates on Earth. Due to its relative remoteness, it remains unclaimed by any sovereign nation.
Activity
[edit]Scientists and researchers debate whether or not the 138 identified possible volcanoes are active or dormant. It is very hard to definitively say, given that many of these volcanic structures are buried underneath several kilometers of ice.[9] However, ash layers within the West Antarctic Ice Sheet[10], as well as deformations in the ice surface[11] indicate that the West Antarctic Rift System could be active and contain erupting volcanoes. Additionally, seismic activity in the region hints at magma movement beneath the crust, a sign of volcanic activity.[8] Despite this, however, there is not yet definitive evidence of presently active volcanoes.
Subglacial volcanism is often characterized by ice melt and subglaical water.[12] Though there are other sources of subglacial water, such as geothermal heat, it almost always is a condition of volcanism. Scientists remain uncertain about the presence of water underneath the West Antarctic Ice Sheet, with some claiming to have found evidence indicating the existence.
Conditions of Formation
[edit]In West Antarctica's Marie Byrd Land, volcanoes are typically composed of alkaline and basaltic lava. Sometimes, the volcanoes are entirely basaltic in composition. Due to the geographic similarity of the Marie Byrd Land, it is believed that the volcanoes in in the West African Rift System are also composed of basalt.[4]
Above-ice basaltic volcanoes, also known as subaerial basaltic volcanoes, generally form in tall, broad cone shapes.[4] Since they are formed from repeated piling of liquid magma sourced from the center, they spread widely and grow upwards relatively slowly.[13] However, West Antarctic Volcanoes form underneath ice sheets, and are thus categorized as subglacial volcanoes. Subglacial volcanoes that are monogenetic are far more narrow, steeper, flat topped structures. Polygenetic subglacial volcanoes have a wider variety of shapes and sizes due to being made up of many different eruptions. Often, they look more cone shaped, like statovolcanoes.
Hazards
[edit]Hazardous Ash
[edit]Little has been studied about the implications of volcanic ash from eruptions within the Antarctic Circle. It is likely that an eruption at lower latitudes would cause global health and aviation hazards due to ash disbursement. The clockwise air circulation around the low pressure system at the South Pole forces air upwards, hypothetically sending ash upwards towards the Stratospheric jet streams, and thus quickly dispersing it throughout the globe.[14]
Melting Ice
[edit]Recently, in 2017, a study found evidence of subglacial volcanic activity within the West Antarctic Ice Sheet. This activity poses a threat to the stability of the Ice Sheet, as volcanic activity leads to increased melting.[15] This could possibly plunge the West Antarctic Ice Sheet into a positive feedback loop of rising temperatures and increased melting.
Citations
[edit]- ^ "Mount Erebus", Wikipedia, 2019-01-20, retrieved 2019-02-06
- ^ "91 volcanoes discovered beneath Antarctica's ice. But are they active?". USA TODAY. Retrieved 2019-01-18.
- ^ van Wyk de Vries, M., Bingham, R. G. & Hein, A. S. A new volcanic province: an inventory of subglacial volcanoes in West Antarctica. Geol. Soc. Lond. Spec. Publ. 461 (2017).
- ^ a b c Hein, Andrew S.; Bingham, Robert G.; Vries, Maximillian van Wyk de (2018-01-01). "A new volcanic province: an inventory of subglacial volcanoes in West Antarctica". Geological Society, London, Special Publications. 461 (1): 231–248. doi:10.1144/SP461.7. ISSN 0305-8719.
- ^ "Global Volcanism Program | Erebus". volcano.si.edu. Retrieved 2019-03-14.
- ^ Smellie, 2000. Subglacial eruptions. In: Sigurdsson, H. (ed.) Encyclopaedia of Volcanoes. Academic Press, San Diego, pp. 403-418. Smellie, 2006. The relative importance of supraglacial versus subglacial meltwater escape in basaltic subglacial tuya eruptions: an important unresolved conundrum. Earth-Science Reviews, 74, 241-268.
- ^ "What is Glaciovolcanism?". WorldAtlas. Retrieved 2019-02-19.
- ^ a b Winberry, J. P. & Anandakrishnan, S. Crustal structure of the West Antarctic rift system and Marie Byrd Land hotspot. Geology 32, 977–980 (2004).
- ^ LeMasurier, W. E. Neogene extension and basin deepening in the West Antarctic rift inferred from comparisons with the East African rift and other analogs. Geology 36, 247–250 (2008).
- ^ Iverson, N. A. et al. The first physical evidence of subglacial volcanism under the West Antarctic Ice Sheet. Sci. Rep. 7, 11457 (2017).
- ^ Behrendt, J. C., Finn, C. A., Blankenship, D. D. & Bell, R. E. Aeromagnetic evidence for a volcanic caldera complex beneath the divide of the West Antarctic ice sheet. Geophys. Res. Lett. 25, 4385–4388 (1998).
- ^ King, E. C., Woodward, J. & Smith, A. M. Seismic evidence for a water-filled canal in deforming till beneath Rutford Ice Stream, West Antarctica. Geophys. Lett. 31 (2004).
- ^ "Types of Volcanoes". volcano.oregonstate.edu. Retrieved 2019-01-28.
- ^ Geyer, Adelina; Marti, Alejandro; Folch, A.; Giralt, Santiago (2017-04-23). "Antarctic volcanoes: A remote but significant hazard". doi:http://dx.doi.org/10.13039/501100003329.
{{cite journal}}: Check|doi=value (help); Cite journal requires|journal=(help); External link in|doi= - ^ Golden, Ellyn; Kim, Ellen; Rachel Obbard; Dunbar, Nelia W.; Lieb-Lappen, Ross; Iverson, Nels A. (2017-09-13). "The first physical evidence of subglacial volcanism under the West Antarctic Ice Sheet". Scientific Reports. 7 (1): 11457. doi:10.1038/s41598-017-11515-3. ISSN 2045-2322.