FOR those that thought Yellowstone super-volcano was one of the biggest natural threats to the USA, think again.
Eruptions at Snake River Plain in Idaho were “significantly larger” than geologists had previously thought.
Scientists from the University of Leicester discovered there were a staggering 12 massive eruptions over the course of four million years, beginning 12 million years ago.
The massive eruptions helped to form the 100 kilometre-wide Snake River Basin, with one of the most powerful eruptions occurring 8.1 million years ago. The eruption's volume exceeded 1,900 km3 and created a 1.3km thick caldera.
Furthermore, the Snake River Plain is situated on the Yellowstone Hotspot track, a region which spans from Nevada, through Oregon and Idaho and then to Wyoming where Yellowstone Volcano is located.
Snake River Plain may have something deadly lurking beneath the surface.
April 2016 – IDAHO – For those that thought Yellowstone super-volcano was one of the biggest natural threats to the USA, think again. Eruptions at Snake River Plain in Idaho were “significantly larger” than geologists had previously thought. Scientists from the University of Leicester discovered there were a staggering 12 massive eruptions over the course of four million years, beginning 12 million years ago.
The massive eruptions helped to form the 100 kilometer-wide Snake River Basin, with one of the most powerful eruptions occurring 8.1 million years ago. The eruption’s volume exceeded 1,900 km3 and created a 1.3km thick caldera. Furthermore, the Snake River Plain is situated on the Yellowstone Hotspot track, a region which spans from Nevada, through Oregon and Idaho and then to Wyoming where Yellowstone Volcano is located.
Dr Tom Knott from the University of Leicester, said: “While it is well-know that Yellowstone has erupted catastrophically in recent times perhaps less widely appreciated is that these were just the latest in a protracted history of numerous catastrophic super-eruptions that have burned a track along the Snake River eastwards from Oregon to Yellowstone from 16 Ma to present.
Yellowstone may look stunning, but an eruption would be catastrophic
“The size and magnitude of this newly defined eruption is as large, if not larger, than better known eruptions at Yellowstone, and it is just the first in an emerging record of newly discovered super-eruptions during a period of intense magmatic activity between eight and 12 million years ago.”
Several volcanic rift zones traverse the Snake River Plain. Volcanic rift zones are weak areas where the earth’s crust has been stretched and thinned and fissures have developed. Magma under pressure follows these fissures to the surface.
The most extensive system of fissures on the Snake River Plain is called the Great Rift, which passes through Craters of the Moon. This volcanic rift zone is 60 miles long and from 1.5 to five miles wide. At Craters of the Moon it is characterized by short surface cracks, more than 25 cinder cones, and is the point of origin of over 60 lava flows. Geologists believe that the formation of the Great Rift is related to Basin and Range type faulting.
Eruptions at Craters of the Moon
Most of the lava flows exposed at Craters of the Moon erupted between 2,000 and 15,000 years ago. These flows were deposited during eight eruptive periods, each separated by periods of relative calm. This cycle of eruptions interspersed with periods of calm is associated with the buildup of pressure as magma accumulates beneath the surface. Strain increases until the resistance of the earth’s crust is overcome, magma rises to the surface, and an eruption takes place. As soon as the magmatic pressure dissipates, the eruption ceases until the pressure can build once more.
What Does the Future Hold?
If what geologists tell us proves to be true, it is likely that there will be another eruption at Craters of the Moon. By studying the flows that make up the Craters of the Moon lava field, geologists have been able to determine an eruptive pattern that indicates the area is merely in a stage of dormancy. They believe that past eruptions conform to a predictable time schedule and that the eruptive cycle will begin again within the next 1,000 years.
Scientists Claim to Have Developed System to Predict Cataclysmic SUPERVOLCANO Eruptions that Could END LIFE on Earth
Gigantic volcanic outbursts throw 100 times more superheated gas, ash and rock into the atmosphere than a normal eruption.
Can blanket continents and plunge globe into volcanic winters.
New technique can predict maegaquakes for first time.
It is a discovery that could save the life of million, and safeguard entire species.
Researchers claim to have worked out how to accurately predict the eruption of ‘supervolcanoes’ that blanket the earth in giant ash clouds triggering a ‘nuclear winter’.
They say the discovery could reveal exactly when giant pools of magma greater than 100 cubic miles in volume and formed a few miles below the surface will erupt.
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Repeatedly throughout Earth’s history,when they become a super-eruption, the resulting gigantic volcanic outbursts that throw 100 times more superheated gas, ash and rock into the atmosphere than run-of-the-mill eruptions – enough to blanket continents and plunge the globe into decades-long volcanic winters.
The most recent super-eruption took place about 27,000 years ago in New Zealand, well before humans kept records of volcanic eruptions and their aftermath.
Geologists today are studying deposits from past super-eruptions to try and understand where and how rapidly these magma bodies develop and what causes them to eventually erupt.
Despite considerable study, geologists are still debating how quickly these magma pools can be activated and erupted, with estimates ranging from millions to hundreds of years.
Now a team of geologists have developed a new ‘geospeedometer’ that they argue can help resolve this controversy by providing direct measurements of how long the most explosive types of magma existed as melt-rich bodies of crystal-poor magma before they erupted.
WHAT MAKES A MEGAERUPTION?
The most recent supervolcanic eruption on Earth occurred 27,000 years ago at Taupo located at the center of New Zealand’s north island.
They occur when giant pools of magma greater than 100 cubic miles in volume form a few miles below the surface and erupt.
They throw 100 times more superheated gas, ash and rock into the atmosphere than run-of-the-mill eruptions – enough to blanket continents and plunge the globe into decades-long volcanic winters.
They have applied their new technique to two super-eruption sites and a pair of very large eruptions and found that it took them no more than 500 years to move from formation to eruption.
These results are described in the article ‘Melt inclusion shapes: Timekeepers of short-lived giant magma bodies’ appearing in the November issue of the journal Geology.
Geologists have developed a number of different ‘timekeepers’ for volcanic deposits.
Quartz crystal that developed in molten magma. Black dots are blebs of molten rock captured in the crystal when it formed. Using advanced 3-D X-ray tomography, the researchers were able to measure the size and shape of the melt inclusions with unprecedented precision.
The fact that these techniques measure different processes and have different resolutions, has contributed to this lack of consensus.
‘Geologists have developed a number of different ‘timekeepers’ for volcanic deposits,’ said Guilherme Gualda, associate professor of earth and environmental sciences at Vanderbilt University, who directed the project.
‘The fact that these techniques measure different processes and have different resolutions, has contributed to this lack of consensus.
‘Our new method indicates that the process can take place within historically relevant spans of time,’
The method was developed as part of the doctoral thesis of Ayla Pamukcu, who is now a post-doctoral researcher at Brown and Princeton Universities.
‘The hot spot under Yellowstone National Park has produced several super-eruptions in the past.
‘The measurements that have been made indicate that this magma body doesn’t currently have a high-enough percentage of melt to produce a super-eruption.
But now we know that, when or if it does reach such a state, we will only have a few hundred years to prepare ourselves for the consequences,’ Gualda said.
The researchers’ geospeedometer is based on millimeter-sized quartz crystals that grew within the magma bodies that produced these giant eruptions.
Quartz crystals are typically found in magmas that have a high percentage of silica.
This type of magma is very viscous and commonly produces extremely violent eruptions. Mount St. Helens was a recent example.
The geologists use image process method that describe the edges of a melt inclusion by set of points. Next they use these points to create a 3-D polyhedron (red) that represents the final shape of the melt inclusion.
Once they have the final shape of the bleb, they create a 3D ellipsoid (blue) that represents its initial shape. Then they superimpose the two. The areas of the red polyhedron that extend beyond the surface of the ellipsoid represent the volume of the bleb that has migrated during the faceting process
When the crystals form, they often capture small blobs of molten magma – known as blebs or melt inclusions. Blebs are initially round.
While the crystal is floating in hot magma, diffusion causes them to gradually acquire the polygonal shape of the crystal void that they occupy. But this faceting process can be halted if eruption occurs before complete faceting is achieved.
Using advanced 3-D X-ray tomography, the researchers were able to measure the size and shape of the melt inclusions with exquisite precision.
In cases where the inclusions had not become completely faceted, the researchers could determine how much time had elapsed since they were enclosed.
SCIENTISTS FIND MASSIVE NEW MAGMA CHAMBER UNDER YELLOWSTONE
In the heart of Yellowstone National Park, a supervolcano releases around 45,000 metric tonnes of carbon dioxide each day.
But the magma chamber lying directly beneath its surface is not considered large enough to produce such levels, so researchers have been searching for an alternative source for years.
In April, by tracking seismic waves, geophysicists discovered a huge secondary chamber deeper underground that’s so large its partly-molten rock could fill the Grand Canyon 11 times over.
Previous research found a relatively small magma chamber, known as the upper-crustal magma reservoir, directly beneath the surface in 2013 that measures 2,500 cubic miles (10,420 cubic km).
To discover the latest chamber, Hsin-Hua Huang from the University of Utah and his colleagues tracked seismic waves from almost 5,000 earthquakes.
These readings combined data from the University of Utah Seismograph Stations, which collected shallow readings from nearby quakes in Utah, Idaho, the Teton Range and Yellowstone, and from the Earthscope array, which revealed deeper readings from temblors from more further afield.
Previous research found a relatively small magma chamber, known as the upper-crustal magma reservoir, beneath the surface
Each of these quakes created waves that echoed around the supervolcano.
The movement and structure of these waves could then be used to map the earth beneath.
The researchers said in their paper: ‘The Yellowstone magmatic system from the mantle plume to the upper crust’, published in the journal Science, that the reservoir contains around 98 per cent hot rock.
The remaining 2 per cent is molten rock and is too deep to directly cause an eruption, they added.
‘Previous studies provided us with the data we needed to calculate the rate of the faceting process. We then used this rate, in combination with our shape measurements, to calculate how long the crystal existed in the magma before the eruption,’ said Pamukcu.
In addition, the researchers compared the results obtained with faceting with results obtained using other techniques.
Crystallization may cause variations in concentration of certain elements. In quartz, the element titanium can vary sharply between different zones or layers within the crystal.
Over time, however, the process of diffusion gradually smooths out these variations.
This process also stops at the eruption, so the shallower the slope of titanium concentrations across these boundaries today, the longer the crystal spent in magmatic conditions.
The physics of this process is also well known, so the researchers could use these measurements to provide an independent estimate of how long a crystal spent floating around in the melt.
They found that the duration times they derived from the titanium diffusion measurements agreed closely with those produced by the faceting method.
They applied their geospeedometer to four large eruptions:
‘Our current method will also work on smaller volcanic systems, as long as they erupt magmas that contain quartz crystals,’ said Pamukcu.
‘We are also confident that we can adapt these techniques to work with other minerals, which will allow us to make similar timescale calculations for other types of magmas and volcanoes, like the low-silica basalts commonly erupted from Hawaiian volcanoes.’
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