Supervolcanos and how they could affect global food supply

After hearing the news that the Yellowstone volcano is much larger than assumed, we asked geophysicist Martyn Unsworth about supervolcanos and their effects.

Suzette Chan - 13 March 2014

(Edmonton) Scientists recently discovered that the Yellowstone National Park supervolcano is two-and-a-half times larger than previously thought.

To learn more about supervolcanos, we spoke to Martyn Unsworth , a professor of Physics and of Earth and Atmospheric Sciences at the University of Alberta. Unsworth is studying three volcanos in South America that may have the potential to produce very large eruptions:

Volcan Uturuncu in Southern Bolivia, which has been inflating by 1cm per year over a large area, in a region where more than 10 supervolcanos have occurred in the last 10 million years.

Volcan Lastarria on the Chile-Argentina border, which has had a 1-2 cm uplift per year, a rate that is accelerating.

Laguna del Maule in Chile, which is in a volcanic field with no prior large eruptions, but 30 cm per year uplift. It has been moved to "Yellow" alert status in last couple of years.

Unsworth's group has or will make geophysical measurements at all three sites using electromagnetic waves that can image underground magma bodies, and work out how big they are. The Laguna del Maule study is also related to a geothermal energy project that may extract heat for electricity generation from water that is being heated by the magma body.

Q and A with Martyn Unsworth

Is it possible to tell which volcanoes are supervolcanoes before they erupt? What type of technology or methods are used to make the determination?

A supervolcano is defined as a volcano that can produce an eruption with more than a thousand cubic kilometeres of ejected material. The key is to determine how much magma is stored below them. This requires careful studies, usually centered on geophysical imaging and geological studies of lavas that have been erupted. Seismic studies give useful data, and the work that I do uses electromagnetic waves to measure the amount of magma. Monitoring the location and numbers of small earthquakes is also useful since it tells us if magma is moving.

Is there any way to predict when a supervolcano may go off?

There is great uncertainty about the timescale for a volcano to go from the first signs of unrest to a full scale eruption. Estimates vary all the way from months to years to decades. I am working at several restless volcanos in South America. At each volcano, the key data are very accurate measurements of the elevation of the surface. One volcano in Chile has shown 30 cm per year uplift for five years. This clearly shows that magma is moving towards the surface, but who knows when it might erupt? The surface is showing signs of small cracks and faults developing.

Are there regions that should make emergency plans? What type of emergency plans?

For Yellowstone, the United States Geophysical Survey has extensive monitoring networks to look for changes and the state and federal government have emergency plans.

In South America, plans are less developed. The study we do in Bolivia is in a sparsely populated area, and Bolivia lacks resources to monitor. This is an example of how our research can have very practical benefits. The volcano in Chile is well monitored and has been moved to an elevated alert status several times in recent years in response to increases in earthquake activity.

Would a supervolcano eruption at any of those locations have a visible effect on Canada?

Impacts in Canada from Andean eruptions would be limited in the short term, but a period of climate change and cooler temperatures could disrupt global food supply.

A Yellowstone eruption could dump ash on us. There is ash in the river valley (by the LRT bridge) from the eruption of Mount Mazama in Oregon that formed Crater Lake around 6,000 years ago.

A major Yellowstone eruption would have a huge impact on agriculture in the United States - all the grain producing states are downwind of the volcano.