While no eruption is imminent, scientists from the Alaska Geophysical Institute in Fairbanks recently spent a few days on the flanks of the Mt. Edgecumbe crater, and on surrounding beaches, collecting information on surface temperatures and gasses which they hope sheds light on what’s brewing beneath the surface.
Scene: Samwise and Frodo in Mount Doom – “Don’t you let go!”
You’ve probably seen it a few times, Gollum and the One Ring have plunged into the lava river at the bottom of Mount Doom, and Samwise is trying to pull Frodo back before he suffers the same fate.
Scene: Reach!
Luckily, hobbits have a body chemistry more favorable to heroics inside a volcano. If it had been Aragorn or any of the other human characters in Lord of the Rings helping to destroy the ring, they might have been long gone, passed out in the high concentration of carbon dioxide gas produced in this environment.
CO2 can’t be seen or smelled, but a team of scientists from the Alaska Geophysical Institute knows how to detect it. Six of them spent a few days helicoptering between Sitka and Mt. Edgecumbe in early June, testing the soil of Kruzof Island for CO2.
I caught up with them at the Sitka airport, waiting for a break in the weather.
“So today, hopefully, the weather is looking good, so we’re hoping to make it to the summit of Edgecumbe today,” said Claire Puleio, a doctoral student at the University of Alaska Fairbanks. “And we’re hoping to measure diffuse CO2 – those same CO2 measurements we’ve been taking along the flanks of the volcano, and then if we could get inside the crater, we’d like to take some measurements there. However, it’s unclear if it’s snow-free right now.”
Puleio studies under Research Assistant Professor Társilo Girona, who has a theory that low-temperature thermal anomalies detected by satellite data suggest increased activity in magma that may be a precursor to an eruption. The same CO2 that would make a volcano inhospitable to Aragorn could possibly be warming the flanks of Mt. Edgecumbe.
“One of the hypotheses, we have to understand those signals,” said Girona, “is that the gas that is moving from the magma source to the surface is producing this warming in the surface.”
Girona and Puleio are two of the six members of the team from the Alaska Geophysical Institute studying gas emissions on Mt. Edgecumbe. The project is funded by NASA, as part of a program for early career scientists. They’re tackling the problem on two fronts: in the air, and on the land – or better said, in the land.
Carlo Cardellini is from the University Perugia in Italy. He’s helped develop the method for collecting gas from the soil using a device called an accumulation chamber. But he’s got a slightly more flavorful metaphor.
“And we place a chamber on the top of the soil, it’s like a cooking pot,” said Cardellini. “And we leave the concentration of carbon dioxide to increase inside the chamber. And the rate of increasing is something that is linked to the amount of gas that is passing from the soil to the atmosphere. So we are catching this increase, and we can compute how much gas is escaping from the soil.”
Cardellini uses an infrared sensor that continuously measures the concentration of CO2 in the cooking pot, if you will, but he also collects samples to take back and study in the lab. CO2 produced by magma will have a different isotopic signature than CO2 produced by organic decomposition – and there is a lot of organic decomposition on the slopes of Mt. Edgecumbe, which are primarily wetlands.
For the bigger picture, you’ve got to be airborne. Taryn Lopez is a volcanologist with the Alaska Volcano Observatory. While the others are sampling the slopes of the crater, she’ll be overhead doing what is called a “gas flight.”
“Some gasses exsolve, which means they form bubbles really deep, such as CO2,” Lopez said. “Where things like water and SO2 (sulfur dioxide) which are common volcanic gasses exsolve very shallow. So what we’re looking for is the composition of the gasses. If we see gasses, and if we see the composition, we can tell if the magma is deep or shallow.
Helicopter arrives
This is the first morning of several that the team has been in Sitka, that the rim of the Mt. Edgecumbe crater is visible, 3,200 feet above Sitka Sound, and the helicopter pilot is ready to fly.
Társilo Girona tells me that all the data and information collected by the Geophysical Institute team will be published in several papers, and shared with the Alaska Volcano Observatory, which is sending its own team to Mt. Edgecumbe later this summer. And hopefully, Girona said, “We can better understand how the volcano works.”
