Subscribe to our free daily newsletters
. Earth Science News .




Subscribe to our free daily newsletters



SHAKE AND BLOW
Supervolcanoes likely triggered externally, study finds
by Staff Writers
Champaign IL (SPX) Nov 06, 2015


Supervolcanoes are likely triggered externally when the rock around them cracks or collapses, according to a study led by Illinois geologist Patricia Gregg. Image courtesy L. Brian Stauffer. For a larger version of this image please go here.

Supervolcanoes, massive eruptions with potential global consequences, appear not to follow the conventional volcano mechanics of internal pressure building until the volcano blows. Instead, a new study finds, such massive magma chambers might erupt when the roof above them cracks or collapses.

Knowledge of triggering mechanisms is crucial for monitoring supervolcano systems, including ones that lie beneath Yellowstone National Park and Long Valley, California, according to the study led by Patricia Gregg, University of Illinois professor of geology, in collaboration with professor Eric Grosfils of Pomona College and professor Shan de Silva of Oregon State University. The study was published in the Journal of Volcanology and Geothermal Research. Gregg also presented the findings this week at the annual meeting of the Geological Society of America.

"If we want to monitor supervolcanoes to determine if one is progressing toward eruption, we need better understanding of what triggers a supereruption," Gregg said. "It's very likely that supereruptions must be triggered by an external mechanism and not an internal mechanism, which makes them very different from the typical, smaller volcanoes that we monitor."

A supervolcano is classed as more than 500 cubic kilometers of erupted magma volume. For comparison, Gregg said, Mount St. Helen's ejected about one cubic kilometer of material, so a supervolcano is more than five hundred times larger.

"A typical volcano, when it erupts, can have lasting impacts across the globe," Gregg said. "We've seen that in Iceland when we've had large ash eruptions that have completely disrupted air traffic across Europe. A supereruption takes that to the nth degree."

The new study's findings are contrary to a pair of papers published in the journal Nature Geoscience in 2014 that claim a link between eruption likelihood and magma buoyancy. The magma byouancy hypothesis suggested that magma may be less dense than the rock surrounding it and therefore could push up against the roof, like an ice cube bobbing in water, increasing the pressure within the chamber and triggering an eruption.

"Typically, when we think about how a volcanic eruption is triggered, we are taught that the pressure in the magma chamber increases until it causes an explosion and the volcano erupts," Gregg said. "This is the prevailing hypothesis for how eruptions are triggered. At supervolcanic sites, however, we don't see a lot of evidence for pressurization. When I incorporated buoyancy into my numerical models, I couldn't reproduce the 2014 studies."

Gregg's numerical model incorporates all of the physics - conserving mass, energy and momentum - to calculate what would happen if a large buoyant magma body were to form in the shallow crust. The model showed that even when the chamber was huge and the difference in density was very large between the magma and he surrounding rock - an unlikely scenario - buoyancy added very little pressure to the system.

"The fact that my numerical model was not agreeing with their analytical solution suggested that there was something missing from the analytical solution. So that prompted me to look closer," Gregg said. "What they miss in the buoyancy model is Newtonian physics: The magma may push up, but the roof pushes back down."

The new study found that the size of the magma chamber is a much greater factor in generating supervolcanic eruptions. The buoyancy studies suggested that this correlation was due to having more material pushing up, but the Illinois-led study found that the size of the chamber affects the stability of the rock containing the chamber.

"Previous studies have found that as a magma chamber expands, it pushes the roof up and forms faults," Gregg said. "As these very large magma chambers grow, the roof above may become unstable and it becomes easier to trigger an eruption through faulting or failure within the rock. "

According to the model, if a crack or fault in the roof penetrates the magma chamber, the magma uses the crack as a vent to shoot to the surface. This could trigger a chain reaction that "unzips" the whole supervolcano.

Next, Gregg's group hopes to take advantage of the advanced computing facilities available at the University of Illinois, such as the Blue Waters supercomputer at the National Center for Supercomputing Applications. The researchers are working to create 4-D models that track the evolution of the Long Valley magma chamber over time in greater detail.

"If we see a correlation between magma chamber size and the ability to erupt, it is important to know if supervolcano eruptions are triggered by internal factors or by foundering and faulting in the roof.

It may mean that we have to monitor these volcanoes differently," Gregg said. "If the trigger is an external force, whether it be an earthquake or a fault, then we should look at seismicity, what types of faults are being developed, what is the stability of the roof, and what kinds of activities are happening on the surface that could cause faulting."


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

.


Related Links
University of Illinois at Urbana-Champaign
Bringing Order To A World Of Disasters
When the Earth Quakes
A world of storm and tempest






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Previous Report
SHAKE AND BLOW
Indonesia shuts Bali airport for second day running
Jakarta (AFP) Nov 5, 2015
Bali's international airport will remain closed until Friday due to ash erupting from a nearby volcano, Indonesian officials said, grounding hundreds of flights for a second consecutive day. The Ngurah Rai International Airport on the resort island has been closed since late Tuesday because of a large ash cloud drifting from Mount Rinjani, an active volcano on the nearby island of Lombok. ... read more


SHAKE AND BLOW
Painfully slow rebuild after Philippine super typhoon

Africa's Lake Chad could fuel new migrant crisis: UN

Egypt's Sisi calls for NATO help in Libya 'vacuum'

Nepal at risk of 'humanitarian crisis': US embassy

SHAKE AND BLOW
The secret of resistance: Shattering into a thousand pieces

From good to bad with a copper switch

Diamonds may not be so rare as once thought

Researchers have the chemistry to make a star

SHAKE AND BLOW
Study of cloud cover in tropical Pacific reveals future climate changes

Los Angeles wants backyard cisterns to collect rain water

Austria's largest state goes 100% renewable

Warming waters contributed to the collapse of New England's cod fishery

SHAKE AND BLOW
Satellites shed light on Greenland Ice Sheet response to warming

The Greenland ice sheet contains nutrients from precipitation

U.S. Army, Air Force deploy Strykers north of Arctic Circle

West Antarctic coastal snow accumulation rose 30 percent past century

SHAKE AND BLOW
Faster digestion in kangaroos reduces methane emissions

How plant cell compartments 'chat' with each other

Colombia drought threatens one of world's top coffees

Blowing in the wind: how to stop cow burps warming Earth

SHAKE AND BLOW
Supervolcanoes likely triggered externally, study finds

Indonesia shuts Bali airport for second day running

Cyclone killed eight in southeastern Yemen: official

Rare cyclone batters war-torn Yemen

SHAKE AND BLOW
German diplomat to lead UN Libya talks, ex-envoy heads to UAE

Give our army guns to stop violence, say C.Africa MPs

Africa's long-awaited intervention force finally stutters to life

South Sudan soldiers poach elephants in DR Congo

SHAKE AND BLOW
Early proto-porcelain from China likely made from local materials

Environment and climate helped shape varied evolution of human languages

Divisive religious beliefs humanity's biggest challenge: Grayling

Predicting the human genome using evolution




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News






The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement