Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Classic view wrong, scientists say, huge pots of magma not brewing under most volcanoes

21.04.2004


About 75,000 years ago, some scientists say, the last truly colossal volcanic eruption on Earth came close to wiping out all the primates, including humans. That eruption occurred when the Toba volcano in Indonesia exploded in an almost unbelievably shattering display.



Other people with a flare for the dramatic warn that a supervolcano underlying Yellowstone National Park could erupt in the not-so-distant future and push humanity to the verge of extinction. University of North Carolina at Chapel Hill scientists say not to worry, especially anytime soon.

"It’s not hyperbole to say that the biggest eruptions could bring an end to civilization," said Dr. Allen F. Glazner, professor of geologic sciences at UNC. "Such eruptions are evident in the geologic record, and the classic textbook picture of volcanoes implies that huge pots of magma are brewing under most active volcanoes today."


Happily, that traditional view is wrong, according to Glazner’s latest research -- work conducted jointly with UNC assistant geology professor Dr. Drew S. Coleman and Dr. John M. Bartley of the University of Utah.

In two studies appearing in April issue of GSA Today and the May issue of Geology, the scientists present new insights into the potential for volcanoes to produce gigantic eruptions -- explosions thousands of times larger than the 1980 eruption of Mount Saint Helens.

"Although evidence for such massive eruptions is found throughout the geologic record, our investigation of magmas frozen below long-extinct volcanoes in California’s Sierra Nevada led us to conclude that the largest eruptions are significantly less likely than many people believed," Glazner said.

In their investigation, team members studied magma bodies that cooled beneath the land’s surface. Those bodies, called "plutons" after Pluto, the Greek god of the underworld, are the chief building blocks of the Earth’s crust, he said. Vast pieces of formerly molten rock, they contain many known rock and mineral resources.

"Much of Chapel Hill, for example, lies on the Chapel Hill Granite pluton and its associated volcanic rocks," the geologist said. "Most scientists picture plutons as solidifying from enormous underground blobs of molten rock known as magma that feed overlying volcanoes."

Typically, plutons are hundreds to thousands of cubic kilometers in volume. For that reason, geologists long assumed that huge stores of magma are commonplace active volcanoes, Glazner said. They also reasoned that the potential for truly catastrophic eruptions exists in many volcanically active areas.

"Our new work casts doubt on the assumption that gigantic eruptions should be relatively common," he said.

Glazner, Coleman and Bartley combined observations of the deep Earth provided by seismic waves produced during earthquakes with mathematical modeling of magma cooling and precise dating and field mapping Sierra Nevada plutons.

Because small percentages of liquid in a rock slow seismic waves dramatically, the waves are sensitive probes for the tiniest volumes of molten rock, Glazner said.

"However, even under active volcanoes, seismic waves show little evidence for big blobs of magma," Coleman said. "Our mathematical models indicate that if big magma chambers existed, they should solidify in less than a million years, but new high-precision age determinations completed here at UNC indicate that plutons can take up to 10 million years to form."

New field mapping demonstrated that plutons once thought to be thousands of cubic kilometers of homogeneous rock that cooled from a single magma reservoir preserve subtle evidence of a much slower, piecemeal assembly, he said.

The results suggest that plutons are likely to be built by a multitude of small molten intrusions over millions of years and that plutons are not like a closed can of food waiting to explode when heated, Coleman said.

"We conclude that volcanoes are more prone to chugging along, producing many small -- though still dangerous -- eruptions such as the 1980 eruption of Mount Saint Helens, rather than huge civilization-destroying eruptions," he said.

Former UNC College of Arts and Sciences students Walt Gray and Ryan Z. Taylor, now with the Southwest Research Institute and the U.S. Forest Service, respectively, contributed to the new work. The National Science Foundation supported it.

David Williamson | EurekAlert!
Further information:
http://www.unc.edu/

More articles from Earth Sciences:

nachricht How much biomass grows in the savannah?
16.02.2017 | Friedrich-Schiller-Universität Jena

nachricht Canadian glaciers now major contributor to sea level change, UCI study shows
15.02.2017 | University of California - Irvine

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Biocompatible 3-D tracking system has potential to improve robot-assisted surgery

17.02.2017 | Medical Engineering

Real-time MRI analysis powered by supercomputers

17.02.2017 | Medical Engineering

Antibiotic effective against drug-resistant bacteria in pediatric skin infections

17.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>