Supervolcano eruption mystery solved

Supervolcanoes like Yellowstone can explode without an earthquake or other external trigger, experts have found.

The sheer volume of liquid magma is enough to cause a catastrophic super-eruption, according to an experiment at the European Synchrotron Radiation Facility (ESRF) in Grenoble.

Simulating the intense heat and pressure inside these "sleeping giants" could help predict a future disaster.

The study by a Swiss team from ETH Zurich appears in Nature Geoscience.

Lead author Wim Malfait, of ETH Zurich said: "We knew the clock was ticking but we didn't know how fast: what would it take to trigger a super-eruption?

"Now we know you don't need any extra factor - a supervolcano can erupt due to its enormous size alone.

"Once you get enough melt, you can start an eruption just like that."

There are about 20 known supervolcanoes on Earth - including Lake Toba in Indonesia, Lake Taupo in New Zealand, and the somewhat smaller Phlegraean Fields near Naples, Italy.

Super-eruptions occur rarely - only once every 100,000 years on average. But when they do occur, they have a devastating impact on Earth's climate and ecology.

When a supervolcano erupted 600,000 years ago in Wyoming, in what today is Yellowstone National Park, it ejected more than 1,000 cubic km of ash and lava into the atmosphere - enough to bury a large city to a depth of a few kilometres.

Lake Toba in Sumatra was formed during the eruption of a supervolcano 74,000 years ago

This ejection was 100 times bigger than Mount Pinatubo in the Philippines in 1992 and dwarfs even historic eruptions like Krakatoa (1883).

"This is something that, as a species, we will eventually have to deal with. It will happen in future," said Dr Malfait.

"You could compare it to an asteroid impact - the risk at any given time is small, but when it happens the consequences will be catastrophic."

Being able to predict such a catastrophe is obviously critical. But the trigger has remained elusive - because the process is different from conventional volcanoes like Pinatubo and Mount St Helens.

One possible mechanism was thought to be the overpressure in the magma chamber generated by differences between the less dense molten magma and more dense rock surrounding it.

"The effect is comparable to holding a football under water. When you release it, the air-filled ball is forced upwards by the denser water around it," said Wim Malfait, of ETH Zurich.

But whether this buoyancy effect alone was enough was not known. It could be that an an additional trigger - such as a sudden injection of magma, an infusion of water vapour, or an earthquake - was required.

More Information: dx.doi.org/10.1038/ngeo2042

Mars crater may actually be ancient supervolcano

Seen above, for the basin and surrounding area, higher elevations (reds and yellows) and lower elevations (blues and grays) are indicated. Credit: NASA/JPL/GSFC

A research project led by Joseph R. Michalski, Senior Scientist at the Planetary Science Institute, has identified what could be a supervolcano on Mars – the first discovery of its kind.

In a paper published Oct. 3 in the journal Nature, Michalski and co-author Jacob E. Bleacher of NASA Goddard Space Flight Center describe a new type of volcanic construction on Mars that until now has gone unrecognized.

The volcano in question, a vast circular basin on the face of the Red Planet, previously had been classified as an impact crater.

Researchers now suggest the basin is actually the remains of an ancient supervolcano eruption.

Their assessment is based on images and topographic data from NASA's Mars Odyssey, Mars Global Surveyor and Mars Reconnaissance Orbiter (MRO) spacecraft, as well as the European Space Agency's Mars Express orbiter.

In the Nature paper Michalski and Bleacher lay out their case that the basin, recently named Eden Patera, is a volcanic caldera. Because a caldera is a depression, it can look like a crater formed by an impact, rather than a volcano.

"On Mars, young volcanoes have a very distinctive appearance that allows us to identify them," Michalski said. "The long-standing question has been what ancient volcanoes on Mars look like. Perhaps they look like this one."

Above, the dark color indicates younger material draped across the Eden Patera depression. 

Credit: ESA

The researchers also suggest a large body of magma loaded with dissolved gas (similar to the carbonation in soda) rose through thin crust to the surface quickly.

Like a bottle of soda that has been shaken, this supervolcano would have blown its contents far and wide if the top came off suddenly.

"This highly explosive type of eruption is a game-changer, spewing many times more ash and other material than typical, younger Martian volcanoes," Bleacher said.

"During these types of eruptions on Earth, the debris may spread so far through the atmosphere and remain so long that it alters the global temperature for years."

After the material is expelled from the eruption, the depression that is left can collapse even further, causing the ground around it to sink.

Eruptions like these happened in ages past at what is now Yellowstone National Park in the western United States, Lake Toba in Indonesia and Lake Taupo in New Zealand.

More information: www.nature.com/nature/journal/v502/n7469/full/nature12482.html

Galactic 'Supervolcano' Seen Erupting With X-Rays

A galactic "supervolcano" in the massive galaxy M87 is erupting, blasting gas outwards. The cosmic volcano — driven by a giant black hole in M87's center — is preventing hundreds of millions of new stars from forming.

An image, taken by NASA's Chandra X-ray Observatory and the National Radio Astronomy Observatory's Very Large Array, captures the drama in action. [Photo of the galactic "supervolcano."]

"Our results show in great detail that supermassive black holes have a surprisingly good control over the evolution of the galaxies in which they live," said Norbert Werner of the SLAC National Accelerator Laboratory in Melo Park, Calif., who led one of two studies of M87's black hole and its effects. "The black hole's reach extends ever farther into the entire cluster, similar to how one small volcano can affect practically an entire hemisphere on Earth."

X-ray galaxy

M87 is about 50 million light-years from Earth and lies at the center of the Virgo cluster, which contains thousands of galaxies. M87 is filled with hot gas that emits X-ray light, which is detectable by Chandra. As the gas cools, it can fall toward the galaxy's center, where it should continue to cool even faster and form new stars.

Yet, radio observations from the Very Large Array suggest that in M87, jets of very energetic particles produced by the black hole interrupt this process. These jets lift up the relatively cool gas near the galaxy's center and produce shock waves in the galaxy's atmosphere from their supersonic speed.

Scientists have found that the interaction of this cosmic "eruption" with the galaxy's environment is very similar to volcanic processes on Earth. In particular, the researchers compared it to the aftermath of the Eyjafjallajokull volcanic eruption, which forced much of Europe to close its airports earlier this year.

The energetic particles produced near the black hole rise through the X-ray-emitting atmosphere of the cluster, lifting up the coolest gas near the center of M87 in their wake, similar to the way hot volcanic gases drag up clouds of dark ash.