15 December 2017

Subterranean Serendipity: Scientists stumble upon a new way to sample magma

Posted by Joseph Cariz

By Annie Roth

Krafla Caldera in northeast Iceland. The large red building near the center is the Landsvirkjun National Power Company’s 60 MWe power plant. Some of the pipes that carry steam from the geothermal wells to the plant are visible.
Credit: J. Eichelberger

Scientists may have found a way to tap into the most powerful force on Earth: volcanism.

Over the past decade, geothermal drilling has led to the discovery of at least three magma chambers, subterranean pockets of viscous molten rock, fewer than 2.5 kilometers (1.5 miles) below Earth’s surface. Under the right amount of pressure, the magma stored in these pockets can force its way to the surface and cause a volcanic eruption.

Scientists have never directly observed magma beneath the Earth’s surface. But thanks to the discovery of these easily accessible magma chambers, it may now be possible, report scientists at the 2017 American Geophysical Union Fall Meeting in New Orleans.

A research team from the University of Alaska Fairbanks presented their plan to collect core samples from shallow magma chambers at the annual meeting of Earth and space scientists. If they are successful, the data they collect would increase scientists’ understanding of geologic processes, improve the accuracy of eruption forecasts and drastically increase the efficiency of geothermal energy production, according to the researchers.

The plan

In 2009, a team of engineers from the Iceland Deep Drilling Program, a hydrothermal energy consortium, attempted to establish a new geothermal energy extraction facility near the Krafla volcano in Iceland. But exploratory drilling ended abruptly when one of their drills encountered a magma chamber less than 2.2 kilometers (1.4 miles) below the surface. The discovery of such an easily accessible magma chamber gave scientists their first opportunity to study magma in its natural location. In an unprecedented achievement, an international team of scientists managed to successfully sample the roof of the magma body under Krafla using geothermal drilling equipment.

Scientists have long speculated how to locate subterranean magma chambers but none of their theories were ever tested, according to the researchers. Almost all known magma chambers were discovered accidentally during exploratory geothermal drilling operations.

“All of these [magma encounters] have been a surprise,” said John Eichelberger, a professor at the University of Alaska Fairbanks who presented the magma sampling plan. “We are trying to go back to one of these surprises and drill a scientifically planned hole, not to get steam, but to actually get core samples across the boundary from solid rock to liquid rock.”

Eichelberger plans on using specialized drilling equipment to collect larger core samples from the Krafla magma chamber by 2020.

Magma splattering out of a lava pond near the northeast cone of Kilauea, Hawaii’s most active volcano. Kilauea is one of a handful of volcanic sites where geothermal drilling has led to the discovery of a shallow magma chamber.
Credit: USGS

Improving eruption forecasting

Volcanic eruptions are notoriously hard to predict. For decades, scientists have relied on volcanic fume content and seismic activity to provide them with early warning signs of imminent eruptions. Unfortunately, this kind of data can only detect magma movement, which doesn’t always result in an eruption.

According to Eichelberger, understanding what is happening inside the magma chamber is key to accurately predicting eruptions. He suspects putting instruments that can measure the temperature and pressure inside the magma chamber could allow scientists to improve the accuracy of their eruption forecasts by orders of magnitude.

Providing unlimited energy

Drilling into the magma could also help scientists figure out how to harness the geothermal energy inside of it, according to Eichelberger. Recent advancements in energy conservation technology have allowed geothermal drilling operations to drill closer to underground heat sources like magma. Scientists have not figured out exactly how to harness geothermal energy directly from magma but Eichelberger believes it’s by no means impossible.

“This is something the geothermal sector is generally working on now,” said Anette Mortensen, project manager for National Power Company of Iceland who was not involved with the new research. “There are some challenges we need to work on to utilize this energy but that’s where we stand today. We know there are resources to be explored but we need to do more to utilize it.”

— Annie Roth is a graduate student in the Science Communication program at UC Santa Cruz. To see more of her work, visit www.RothReporting.com. Follow her on twitter at @AnnieRoth_AtSea.