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9/5/2018 — Education, Science and Technology
The slow but deadly genesis of super volcanoes

A geological study on plate tectonic stress has produced novel models that offer a way to predict when a super-volcano will erupt.

Results of the study suggest that we’ll have more time before an eruption than we might expect.

Writing for the website EuropeanScientist, Australian journalist Graeme Beaton, who is domiciled in the United States, cited the study, published in Geophysical Research Letters, and authored by researchers from the University of Illinois, as showing an investigation into tectonic stress as a trigger for super-volcanic eruptions.

This paper was produced before the devastating Kilauea volcanic eruption in Hawaii which to yesterday had destroyed 36 homes, wrecked industry and blocked arterial roads.

Beaton said catastrophic caldera forming volcanoes, or super-volcanoes, are aptly named because their eruption would indeed be catastrophic – on a global scale. Thus, reliable ways of predicting when these structures will erupt are imperative.

The report cited two examples of super-volcanoes - the Yellowstone caldera, in the US’ Yellowstone National Park, and the Taupo volcano on New Zealand’s North Island.

“It has been the running assumption in geology that volcanoes erupt when the hot magma underneath breaks through the roof rock after building up pressure over time,” Beaton wrote.

“But Illinois researchers, noting that the earth’s super-volcanoes are typically in areas of high-tectonic stress, wanted to investigate how much influence tectonic plate motion has in triggering a super-volcanic eruption.

Based on the volcanic zone where New Zealand’s Taupo volcano is located, these researchers developed a model of a super-volcano with which they could run various scenarios, observing the outcomes of different forms of tectonic stress on the volcano’s equilibrium. (The original Mount Taupo is now a massive lake as a result of an eruption 27,000 years ago that saw residue deposited in Japan).

It was found that the type of tectonic stress mattered little in the event of an eruption; all forces – compressional, extensional, and shear – will amount to an eruption.

It was where the new model incorporated a super-volcano’s magma supply that their results came full circle to the original assumption they were aiming to elaborate on in their study.

Pressure from accumulating magma will eventually amount to an eruption, but what the what the University of Illinois authors noted was “the most important outcome” of their work being that, once new magma begins to be injected into a super-volcano – a period of “rejuvenation”, as it is called – the volcano is only stable for a period of hundreds to thousands of years.

Senior author of the study Professor Patricia Gregg said that they “were initially surprised by this very short timeframe”. Super-volcanoes are known to remain dormant for period of over a million years. What the new model shows is that, once the period of a super-volcano’s rejuvenation begins, it is a short time before a “large scale eruption” results.

The EuropeanScientist said that short on a geological timescale – but on a human timescale, it will be a long wait, from several lifetimes to thousands of years, from the time a super-volcano begins its period of rejuvenation to the time it erupts.

Researchers said that during that time there will be ample warning with “precursors to catastrophic eruption - far greater and long-lasting than anything yet documented.”

Prof Gregg said warning signs would include earthquakes, faulting of tectonic plates, and uplift of volcanic zones measuring hundreds of metres. The “models predict that the system would inflate for hundreds to thousands of years before we witness catastrophic eruption.”

Source: europeanscientist.com; nzresources.com

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Lava from Mt Kilauea reaches the sea. Photo: Kilauea Lodge.