Featured Research

from universities, journals, and other organizations

Possible trigger for volcanic 'super-eruptions' discovered

Date:
October 12, 2011
Source:
Oregon State University
Summary:
The "super-eruption" of a major volcanic system occurs about every 100,000 years and is considered one of the most catastrophic natural events on Earth, yet scientists have long been unsure about what triggers these violent explosions. A new model points to a combination of temperature influence and the geometrical configuration of the magma chamber as a potential cause for these super-eruptions.

Volcano.
Credit: © Beboy / Fotolia

The "super-eruption" of a major volcanic system occurs about every 100,000 years and is considered one of the most catastrophic natural events on Earth, yet scientists have long been unsure about what triggers these violent explosions.

However, a new model presented this week by researchers at Oregon State University points to a combination of temperature influence and the geometrical configuration of the magma chamber as a potential cause for these super-eruptions.

Results of the research, which was funded by the National Science Foundation, were presented at the annual meeting of the Geological Society of America in Minneapolis, Minn.

Patricia "Trish" Gregg, a post-doctoral researcher at OSU and lead author on the modeling study, says the creation of a ductile halo of rock around the magma chamber allows the pressure to build over tens of thousands of years, resulting in extensive uplifting in the roof above the magma chamber. Eventually, faults from above trigger a collapse of the caldera and subsequent eruption.

"You can compare it to cracks forming on the top of baking bread as it expands," said Gregg, a researcher in OSU's College of Oceanic and Atmospheric Sciences. "As the magma chamber pressurizes at depth, cracks form at the surface to accommodate the doming and expansion. Eventually, the cracks grow in size and propagate downward toward the magma chamber.

"In the case of very large volcanoes, when the cracks penetrate deep enough, they can rupture the magma chamber wall and trigger roof collapse and eruption," Gregg added.

The eruption of super-volcanoes dwarfs the eruptions of recent volcanoes and can trigger planetary climate change by inducing Ice Ages and other impacts. One such event was the Huckleberry Ridge eruption of present-day Yellowstone Park about two million years ago, which was more than 2,000 times larger than the 1980 eruption of Mount St. Helens in Washington.

"Short of a meteor impact, these super-eruptions are the worst environmental hazards our planet can face," Gregg said. "Huge amounts of material are expelled, devastating the environment and creating a gas cloud that covers the globe for years."

Previous modeling efforts have focused on an eruption trigger from within the magma chamber, which scientists thought would leave a visible trace in the form of a precursor eruption deposits, according to Shanaka "Shan" de Silva, an OSU geologist and co-author on the study. Yet there has been a distinct lack of physical evidence for a pre-cursor eruption at the site of these super-volcanoes.

The model suggests the reason there may be no precursor eruption is that the trigger comes from above, not from within, de Silva pointed out.

"Instead of taking the evidence in these eruptions at face value, most models have simply taken small historic eruptions and tried to scale the process up to super-volcanic proportions," de Silva said. "Those of us who actually study these phenomena have known for a long time that these eruptions are not simply scaled-up Mt. Mazamas or Krakataus -- the scaling is non-linear. The evidence is clear."

It takes a "perfect storm" of conditions to grow an eruptible magma chamber of this size, Gregg says, which is one reason super-volcano eruptions have occurred infrequently throughout history. The magma reservoirs feeding the eruptions could be as large as 10,000- to 15,000-square cubic kilometers, and the chamber requires repeated intrusions of magma from below to heat the surrounding rock and make it malleable. It is that increase in ductility that allows the chamber to grow without magma evacuation in a more conventional manner.

When magma chambers are smaller, they may expel magma before maximum pressure is reached through frequent small eruptions.

The Yellowstone eruption is one of the largest super-volcano events in history and it has happened several times. Other super-volcano sites include Lake Toba in Sumatra, the central Andes Mountains, New Zealand and Japan.

Gregg said that despite its explosive history, it doesn't appear that Yellowstone is primed for another super-eruption anytime soon, though the slow process of volcanic uplift is taking place every day.

"The uplift of the surface at Yellowstone right now is on the order of millimeters," she explained. "When the Huckleberry Ridge eruption took place, the uplift of the whole Yellowstone region would have been hundreds of meters high, and perhaps as much as a kilometer."

Other authors on the investigation include Erik Grosfils, of Pomona College, and John Parmigiani, an OSU engineer.


Story Source:

The above story is based on materials provided by Oregon State University. Note: Materials may be edited for content and length.


Cite This Page:

Oregon State University. "Possible trigger for volcanic 'super-eruptions' discovered." ScienceDaily. ScienceDaily, 12 October 2011. <www.sciencedaily.com/releases/2011/10/111012124139.htm>.
Oregon State University. (2011, October 12). Possible trigger for volcanic 'super-eruptions' discovered. ScienceDaily. Retrieved September 16, 2014 from www.sciencedaily.com/releases/2011/10/111012124139.htm
Oregon State University. "Possible trigger for volcanic 'super-eruptions' discovered." ScienceDaily. www.sciencedaily.com/releases/2011/10/111012124139.htm (accessed September 16, 2014).

Share This



More Earth & Climate News

Tuesday, September 16, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Scientists Examine Colossal Squid

Raw: Scientists Examine Colossal Squid

AP (Sep. 16, 2014) — Squid experts in New Zealand thawed and examined an unusual catch on Tuesday: a colossal squid. It was captured in Antarctica's remote Ross Sea in December last year and has been frozen for eight months. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Man Floats for 31 Hours in Gulf Waters

Man Floats for 31 Hours in Gulf Waters

AP (Sep. 16, 2014) — A Texas man is lucky to be alive after he and three others floated for more than a day in the Gulf of Mexico when their boat sank during a fishing trip. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Researchers Explore Shipwrecks Off Calif. Coast

Researchers Explore Shipwrecks Off Calif. Coast

AP (Sep. 16, 2014) — Federal researchers are exploring more than a dozen underwater sites where they believe ships sank in the treacherous waters west of San Francisco in the decades following the Gold Rush. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Conservationists Face Uphill PR Battle With New Shark Rules

Conservationists Face Uphill PR Battle With New Shark Rules

Newsy (Sep. 14, 2014) — New conservation measures for shark fishing face an uphill PR battle in the fight to slow shark extinction. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



    Save/Print:
    Share:  

    Free Subscriptions


    Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

    Get Social & Mobile


    Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

    Have Feedback?


    Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
    Mobile iPhone Android Web
    Follow Facebook Twitter Google+
    Subscribe RSS Feeds Email Newsletters
    Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins