Edmonton

Making the most of magma: Edmonton researcher explores restless Chilean volcano

Martyn Unsworth is travelling to Chile to study a restless volcano which appears to be on the verge of eruption.

'This volcano is unusual because we've got signs there might be something bigger happening'

Laguna del Maule in the southern Andes, Chile has been showing signs of unrest for years. (Martyn Unsworth)

Martyn Unsworth is travelling to Chile to study a restless volcano which appears to be on the verge of eruption.

The Edmonton researcher is searching the warning signs of growing unrest beneath its surface. 

Much like humans, volcanoes inhale and exhale at a certain rhythm. But the Laguna del Maule volcanic field in the Southern Andes has only been inhaling — for five years in a row.

The eroded earth which contains the large, potentially hazardous caldera volcano has been steadily shifting upwards at an astonishing rate of 30 centimetres a year. That's among the highest rates of uplift ever measured for a volcano that is not actively erupting.

Researchers believe it's an expanding pool of molten hot magma.

"All volcanoes, they move upwards and downwards like someone breathing, but this one is moving quickly, and upwards," said Martyn Unsworth, a geophysics professor in the Department of Earth and Atmospheric Sciences at the University of Alberta.

The restless deposit of magma provides a major scientific opportunity: to explore a volcano before it erupts.

All volcanoes, they move upwards and downwards like someone breathing, but this one is moving quickly, and upwards.- Martyn Unsworth, geophysics professor, University of Alberta

"This volcano is unusual because we've got signs there might be something bigger happening," Unsworth said in an interview with CBC Edmonton's Radio Active.

"We can hopefully see the signals that lead up to that to help us understand when a volcano's going to erupt."

Laguna del Maule — composed of domes and ash deposits that centre around a lake that straddles the Chilean-Argentine border — looks nothing like a classic, cone-shaped volcano.  

The reason for its unusual formation is the nature of the molten rock underground. It's called rhyolite, and it's the most explosive type of magma on the planet.

The eruption of a rhyolite volcano is too quick and violent to build up a cone. Instead, this water-rich magma often explodes into massive quantities of ash that can form deposits hundreds of yards deep, followed by a slower flow of glassy magma that can cover kilometres of earth.

"It's not actually a pointed mountain like many volcanoes. It's actually an area with lots of smaller lava flows," Unsworth said. "And there's really good evidence that not too far below the surface there is this pool of molten rock."

About 130 volcanic vents exist in the field and the earliest eruptions occurred 1.5 million years ago.

University of Alberta Geophysicst Martyn Unsworth at Laguna del Maule, Chile. (Martyn Unsworth/University of Alberta)

'All the subtle signals ... are simply destroyed'

Predicting what kind of eruption will occur next at Laguna del Maule is tricky.

Unsworth and his team will be using radio waves to create images of the earth's subsurface.

These detailed scans will provide insight into the composition of what lies beneath, in an attempt to map the size of the magma body that has been feeding eruptions for the last 20,000 years.

Researchers are interested to know how much water and magma is present. The combination of the gases inside the calderas will determine whether an eruption would be a slow cascade or a dramatic explosion of ash and magma.

By examining the volcano before an anticipated eruption, Unsworth hopes to overcome an inherent challenge of studying volcanoes — when they do erupt, much of the geological record is erased. 

"If you go to a volcano, all the subtle signals that may have been there prior to the eruption are simply destroyed in the blast," he said. 

"So by looking beforehand you have a chance to see what is happening and try to judge those changes. If we have advanced knowledge, we can mitigate the impact on communities."

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