Digging for Answers

Western Washington University Assistant Professor of Geology Kristina Walowski is a bit like an FBI profiler: She arrives on the scene and reads the clues to learn more about the explosive personality of her subject. But unlike the FBI, she doesn’t have any hope of stopping the perpetrator from acting again—not when her subject is a 4,000-foot stratovolcano rising from the sea in southern Alaska.

In June 2022, Walowski and her two graduate students, Sloane Kennedy and Mahinaokalani Robbins, spent six days on the flanks of the Augustine volcano on the southern end of Cook Inlet, one of the newest and potentially most dangerous volcanoes in the country. Their work was part of a $300,000 National Science Foundation grant with colleagues Alison Koleszar of Colgate University and Matt Loewen of the U.S. Geological Survey’s Alaska Volcano Observatory.

Walowski says the grant is a prime opportunity to observe and examine an active volcano that threatens Alaska’s most populated areas.

“Augustine is a ‘baby volcano’ in the geologic sense, but it’s very active,” says Walowski. “Most of its rocks are only 25,000 years old or even newer; Koma Kulshan (Mount Baker) near our campus in Bellingham in the Cascades, for example, is hundreds of thousands of years old, so you can see how young Augustine really is.”

“Active” is a nice way geologists have of saying that a volcano is prone to erupting, and in the case of Augustine, how dangerous or “explosive” that eruption might be.

“We went to Augustine to look at evidence of past eruptions in the hopes of better understanding what is triggering these eruptions, and how these triggers might either make an eruption very explosive and very hazardous, or less so,” she says.

Augustine had major eruptions in 2006, 1986, 1976, 1963-64, 1935 and 1883, with many minor eruptions throughout. Evidence also points to even larger eruptions about 400 and about 800 years ago.

The volcano dominates a small island at the far southwest end of Cook Inlet; 177 miles to the northeast, at the end of the inlet, is Anchorage, Alaska’s most populous city with about 288,000 people. Another 5,700 or so residents of Homer are about 60 miles to the east. Augustine’s history encompasses almost every type of eruption, from ash plumes to explosions hurling fist-sized rocks thousands of feet into the air. But the volcano’s tendency to build its summit dome until it collapses in a massive landslide—akin to the disintegration of the north face of Mount St. Helens in 1980—poses a dire threat for the now-populous Cook Inlet coast: tsunami.

In a 1987 Science journal article, scientists used mathematical modeling to show the volcano’s northeast face collapsed in 1883, triggering a massive debris avalanche that pushed almost two miles into the shallow waters of Cook Inlet and created a 20-foot tsunami that hit English Bay, across the inlet on the Kenai Peninsula. Thankfully the tsunami hit at low tide and damage was minimal, but it isn’t hard to imagine what kind of catastrophe such a tsunami could wreak on more populated modern-day Alaska, especially if it happened at high tide.

“That’s why we were there,” Walowski says. “To analyze the clues left behind to better understand the eruptive personality of this volcano.”

Island volcanoes have had these types of dangerous avalanches and resulting tsunamis for the length of recorded history; a 1792 tsunami generated by the Unzen volcanic complex in Japan killed more than 15,000 people. In 1883, Krakatoa, the deadliest eruption in modern history, had a landslide-generated tsunami more than 120 feet high.

To begin to decipher what is going on in the “plumbing system” underneath Augustine, Walowski and her students dug down to examine the layers and rocks from past eruptions. Using a technique called “componentry,” they studied the ratios of different types of rocks to understand how violent each recent eruption was.

Certain types are rocks are indicative of more sudden, very explosive events; others are formed by more of a longer, slower, less explosive eruption. If crystals are present in the rocks, that can be a great clue as to the temperature and pressure on them when they were created. Some rocks are formed from a single magma source, others can only be formed when two distinct magma sources mix. Each rock gives the “geo-detectives” another clue about what is happening far below, from the pressures and heat to the mineral makeup and viscosity of the magma being pushed through miles of the earth’s crust, ever closer to the volcano’s cone.

“More viscous magmas erupt more explosively because they are more resistant to flow,” Walowski says. “And by that same rule of thumb, hotter, less viscous magmas are generally—but not always—less explosive.”

Once their geochemistry is analyzed, the rocks begin to tell a more complete story of Augustine’s past. And, more importantly, the analysis of the recent past is also a predictor (on the big-picture scale of geologic time) of the volcano’s future.

“Our research, combined with the gas geochemistry monitoring in place on Augustine, gives us a much clearer picture of what the magma underneath the volcano is doing. The monitoring in place, along with our analyses, help make geologists more informed that something may be about to happen at Augustine so they can plan accordingly,” says Walowski.

WWU grad student Sloane Kennedy says the field work on Augustine this summer was an incredible experience that will play a big part in her upcoming decisions around a doctoral program and a career.

“Being at a location that I have been reading and writing about for the last year, viewing the eruption sequence with my own eyes, scooping bags of samples with my bare hands, and taking them back to the lab at Western is the opportunity of a lifetime,” she says. “I am certain my experience at Augustine will be a crucial factor in my success in applying for doctoral programs in fall 2023 and eventually reaching my ultimate career goals.”

Fellow grad student Mahina Robbins agreed that the field work on Augustine was a rare opportunity.

“Collaborating with the AVO (Alaska Volcano Observatory) made me feel that my professional goal of becoming a research volcanologist at an observatory may one day actually be realized,” says Robbins. “For now, I am excited to continue to tease out the chemical puzzles locked away in magmatic crystals over the course of my master’s program at Western.”

Walowski is doing related research via a separate $160,000 National Science Foundation grant on the cinder cones near Mount Lassen, the southernmost Cascade volcano, in Northern California.

This fall, she’ll turn her detective work to Koma Kulshan. Along with WWU Geology Professor Sue DeBari and Central Washington University Assistant Professor Hannah Shamloo, Walowski recently secured a $600,000 NSF grant to study Mount Baker the way she and her students studied Augustine.

That work will begin this fall with the arrival of three new WWU graduate students and two new CWU graduate students, and expand next summer to include students from Northwest Indian College and Whatcom Community College as part of a field-learning experience.

“It’s going to be a great opportunity not only to learn more about the eruptive history and personality of the volcano closest to us here at Western, but to provide valuable fieldwork experience to some really deserving students as well,” Walowski says.