{"id":86208,"date":"2015-05-02T00:05:31","date_gmt":"2015-05-01T22:05:31","guid":{"rendered":"http:\/\/businesstech.co.za\/news\/?p=86208"},"modified":"2015-05-01T14:11:23","modified_gmt":"2015-05-01T12:11:23","slug":"worlds-largest-supervolcano-even-bigger-than-previously-thought","status":"publish","type":"post","link":"https:\/\/businesstech.co.za\/news\/trending\/86208\/worlds-largest-supervolcano-even-bigger-than-previously-thought\/","title":{"rendered":"World’s largest “supervolcano” is even bigger than previously thought"},"content":{"rendered":"

Seismologists have discovered a massive magma reservoir beneath the Yellowstone supervolcano<\/a> in Wyoming, US, that suggests its volcanic system could be more than 5.6 times larger than was previously thought.<\/p>\n

Although it was already known that Yellowstone had one magma reservoir, located about 5-16km (3-10 miles) below the surface, the new study<\/a>, published in Science, has revealed another, much larger reservoir sitting directly below the first, located around 20-50km (12-30 miles) below the surface.<\/p>\n

This reservoir is thought to have a volume of around 46,000 cubic km \u2013 compared to a volume of around 10,000 cubic km for the shallow reservoir.<\/p>\n

To make their discovery scientists analysed the vibrations made by earthquakes that passed beneath the volcano. The technique not only sheds light on this volcano\u2019s potentially life-threatening eruptions<\/a> but it could also help us understand other volcanoes such as Calbuco<\/a>, which is currently erupting in Chile.<\/p>\n

Sleeping beauty<\/h3>\n
\"Luckily<\/a>

Luckily no sign of an eruption anytime soon. gcnmrk5ii\/flickr, CC BY-ND<\/p><\/div>\n

Yellowstone volcano is composed of an immense volcanic crater – known as a caldera – more more than 70km (44 miles) in length, most of which lies within Yellowstone National Park. The volcano rarely erupts lava (it last did so about 70,000 years ago<\/a>, but the magma lying beneath the surface gives rise to spectacular geothermal features, such as geysers and colourful hot springs.<\/p>\n

The last large eruption at Yellowstone was 640,000 years ago<\/a>, and ejected around 1,000 cubic kilometres (240 cubic miles) of volcanic material. This cataclysm created the Yellowstone caldera. To get an idea of the scale of this, the largest eruption in recorded history, Mount Tambora in 1815<\/a>, erupted about a sixth of that.<\/p>\n

Magma reservoirs are thought to occur beneath most volcanoes, and play a crucial role in the dynamics of eruptions. However, they are too deep, and conditions within them too extreme, to be measured directly so volcanologists have to infer information about them using other means, such as measuring seismic waves.<\/p>\n

These waves travel more slowly when they pass through molten rock, and accordingly the group were able to use the velocities of the earthquake waves to infer the presence of a large, deep zone of partially molten material.<\/p>\n

Carbon footprint explained<\/h3>\n
\"Powerful<\/a>

Powerful fissures. Steve Jurvetson\/flickr, CC BY-SA<\/p><\/div>\n

The magma stored in the deeper reservoir probably doesn\u2019t cause eruptions at Yellowstone directly. Instead, it likely acts as a \u201cfeeder\u201d for the smaller, shallower reservoir \u2013 which is the ultimate source of the volcano\u2019s catastrophic eruptions.<\/p>\n

Scientists had suspected the existence of a second magma reservoir at Yellowstone for some time, but this new evidence is among the strongest support of the theory to date.<\/p>\n

The discovery of this second magma reservoir may also help to explain a mysterious feature of the Yellowstone volcano: its carbon footprint. Carbon dioxide gas<\/a> is commonplace at volcanoes (it is given off by rising magma), but Yellowstone\u2019s output, which is around 45,000 tonnes<\/a> of CO2<\/sub> each day, was too high to be explained by a single magma reservoir. But according to the study\u2019s authors, the presence of the new reservoir is enough to account for the volcano\u2019s CO2<\/sub> flux.<\/p>\n

\"Eruption<\/a>

Eruption of Calbuco, seen from nearby Puerto Montt. EPA\/Francisco Negroni<\/p><\/div>\n

If the high-resolution seismic imaging technique used in the study could be repeated at other volcanoes whose deep structure is poorly understood \u2013 such as Calbuco volcano in Chile \u2013 volcanologists might eventually be able to understand how such eruptions take place. The first stirrings of volcanic eruptions happen far below the surface. If researchers can emulate the findings at Yellowstone at other volcanoes, it can only tell us more about the risks they pose.<\/p>\n

By Robin Wylie,\u00a0PhD researcher in Volcanology at UCL<\/span><\/em><\/p>\n