Shortly before dawn on his 80th birthday in July, Don Swanson ’64 (PhD) drove along cracked roadways through the closed Volcanoes National Park to a shuttered tourist hotel near the rim of Hawaii’s erupting Kilauea volcano.

Swanson, a volcanologist with the U.S. Geological Study (USGS), had been working 10 hours a day, seven days a week for months in the hotel’s otherwise empty dining room, with its panoramic view of the summit.

The USGS observatory on the rim, where Swanson had his office, had been so badly damaged by earthquakes in May that it was abandoned and may never reopen. So he turned the hotel into an observation post for visually monitoring the vital signs of what he refers to as “this animal.”

“Kilauea is a kind of organism where everything relates to everything else,” he says in a phone interview. “And it’s happening before your very eyes and not in the distant geological past, so you don’t have to use your imagination.”

After being named scientist-in-charge of the Kilauea observatory in 1996, Swanson has spent much of his time working with other scientists to uncover the volcano’s history of eruptions.

They now believe that in the past 2,500 years, Kilauea has cycled between periods when it has had a high caldera—a large volcanic crater—and produced flowing lava, and periods when it has had a low caldera and produced explosive eruptions. “We now know that Kilauea is not a quiet, docile volcano,” Swanson says. “It can be very violent.”

Their work couldn’t have been more timely. In late April, magma began draining from the mountain through its natural pipes, destroying hundreds of homes 30 miles east and pouring into the sea. The falling magma has also undermined the caldera, causing it to collapse in what Swanson calls “gulps” of about two or three meters at a time on a daily basis. Each time the caldera falls, it triggers a significant earthquake.

The ratcheting down paused in August. But if the caldera starts falling again and reaches the water table, Swanson says, groundwater could mix with the magma to create the pressurized steam that drives violent eruptions.

While Kilauea can’t explode with the force of a Mount St. Helens due to the composition of its magma, it is still dangerous. When the Hawaiian volcano erupted violently in 1790, he says, several hundred people were killed. Past violent eruptions have sent clouds of ash to 30,000 feet, the cruising altitude of many airliners.

“That could have major consequences for the island and the entire state of Hawaii,” Swanson says.

Growing up in southwestern Washington, Swanson could see Mount Rainier from his house and his family picnicked near the foot of Mount St. Helens. But he didn’t decide to become a volcanologist until he came to Hopkins as a graduate student in geology in 1960, where he worked under Aaron Clement Waters, a leading petrologist and structural geologist.

He called his decision to come to Hopkins “the best choice I’ve made in my life.”

After a stint as a NATO postdoc in Europe, Swanson joined the USGS in Menlo Park, California, and in 1968 moved to the Hawaii observatory, where he spent three years studying Kilauea’s nearly continuous eruption. He produced work that later would be described by the Geological Society of America as “a masterpiece which used careful field observation to document numerous new eruptive behaviors.”

Back in the Pacific Northwest in 1971, he investigated the history of the flood basalts of the Columbia River basin with another Hopkins-trained geologist, Thomas L. Wright, now with the Smithsonian.

Shortly after Mount St. Helens began shaking in March 1980, Swanson joined the volcanologists monitoring the mountain. He was scheduled to spend the night of May 17 and the next morning at a USGS trailer parked on a ridge six miles north of the mountain, but he was hosting a visiting graduate student from Germany and asked another USGS volcanologist, David Johnston, 30, to take his shift.

“Dave agreed to babysit,” he says. “He wasn’t looking forward to it, especially. He, more than the rest of us, probably had a better understanding of how explosively Mount St. Helens could erupt.”

The north slope of Mount St. Helens collapsed and exploded at 8:32 the following morning, removing the top 1,300 feet of the mountain and leaving a crater up to two miles wide and half a mile deep. The trailer sat directly in the path of a storm of rock, dust, and wind. Fifty-seven people died. Johnston’s body was never found, though pieces of the trailer were discovered by a road crew 13 years later.

Johnston’s death deeply affected him, Swanson says, and helped him focus his career on better understanding eruptions in order to prevent similar tragedies. “I think about it almost every day.”

After helping to piece together the evolution of Mount St. Helens’ eruption, Swanson mapped parts of the central and southern Cascades of Washington, discovering several extinct volcanoes in the process. He calls his work on Kilauea’s eruptive cycles, which has not yet been completely published, his last major project.

“If Kilauea doesn’t become explosive, good. We’ll all breathe a sigh of relief.” But if it does, he says, at least he has helped alert authorities to the danger.