By Udita Shukla
The magnitude of a volcanic eruption is commonly measured on the Volcanic Explosivity Index (VEI). One of the greatest values measured is around eight. Such high VEI values are attributed to nature’s most dangerous monsters known as super-volcanoes.
Known to spit out eruption deposits amounting to greater than a thousand cubic kilometres (that is, 240 cubic miles), super-volcanoes can either trigger a short-term but massive lava ejection or remain spewing out material for millions of years.
One of the most well-known super-volcanic eruptions is the Kuril Lake eruption that took place at the Kamchatka Peninsula in Russia. The event which occurred around 6,440 BC, is believed to have spewed out around 140 cubic kilometres to 170 cubic kilometres of hot debris. Another recent one, the Taupo Volcanic eruption in New Zealand, around 232 AD, is estimated to have ejected nearly 120 cubic kilometres of material volume.
One of the features that render super-volcanoes elusive is that they are typically depressions on the ground, rather than having steep sides like normal volcanoes. The calderas are so ginormous that they are visible from space.
Emergence of volcanoes
The primary cause of any material outburst is the build-up of uncontrollable pressure that eventually vents itself out through a natural or artificial pathway. This is exactly what transpires underneath the earth’s surface.
Internally, the planet is a hot, boiling concoction of molten metal like iron, nickel, sulphur, along with flowing rock material and minerals. This hot mixture is collectively termed magma and exists in a state of immense, constant pressure within the mantle. When magma sneaks its way into the earth’s crust, through crevices and cracks, this pressure is augmented even more.
Creation of supervolcanoes
When the magma reaches the earth’s crust, it forms a pool, thereby, melting the adjoining rock. The process continues for thousands of years and creates a magma lake. Succumbing to the pressure, the collected material erupts in the form of lava, and drains the pool. The overlying crust collapses over and gives birth to gigantic depressions.
The geographical zones where the crust is plagued by underlying volcanic material are called hotspots. Located in the United States, Yellowstone Caldera is a well-known hotspot and is also a matter of debate among volcanologists and geologists.
A super-volcanic eruption is widely believed to have the potential to trigger a “Volcanic Winter”. This happens when huge quantities of volcanic ash, sulfuric acid and water droplets expelled during a volcanic eruption blocks the sunlight from trickling down into the earth’s atmosphere and increases its albedo (a reflection of solar radiation). The result is a catastrophic reduction in global temperatures.
Recently, a team of researchers led by geologist Jim Kennet at UC Santa Barbara analysed seabed sediment samples from California’s Santa Barbara Basin. The findings reveal the Yellowstone eruption nearly 6,440 years ago consisted of not one, but two super-volcanoes. Although the two eruptions were separated by an intervening time of sound one hundred and seventy years. Scientists believe the two explosions triggered two distinct phases of volcanic winters on Earth.
The Yellowstone supervolcano in the United States has long been suspected to come to life anytime in the near future. Its explosion is expected to plunge the world into a volcanic winter. Moreover, the Campi Flegrei super-volcano in the Bay of Naples, Europe, has been showing signs of re-awakening. The population on top of Capi Flegrei’s seven-mile-long caldera is home to about half a million people.
Scientists have discovered an acceleration process engendering deformation and heating within the hotbed. The finding caused the Italian government elevate the threat level in December 2016. Fears regarding the brewing magma steadily reaching the critical pressure mark, and breaching its quiescent state are afloat, both among government and scientific circles.
In general, the NASA’s answer to a possible threat is to somehow cool the magma lake so that it becomes viscous and sticker, thereby, losing its ability to flow freely and cause havoc. As per the Jet Propulsion Labs team, a super-volcano would have to be cooled by nearly thirty-five percent in order to contain the damage.
The team proposes to carry out the same by drilling into the volcano’s surface to let off the steam. Admittedly, the proposed plan is risky enough to trigger just the kind of explosion it is meant to avoid.
Whatever our next move, if we hope to protect humankind from a future burning apocalypse, rigorous research into the life, evolution and death of super-volcanoes is the need of the hour.
Featured Image Source: VisualHunt
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