AT 8.32 am on 18 May 1980, Mount St Helens erupted. I was about 70 kilometres away in Vancouver, Washington, watching the seismograph, when the instruments started showing major activity. I ran to the radio to call Dave Johnston, my colleague in a field station at the volcano. There was no reply.
I didn’t grasp the scale of the eruption until I was flying over it later that morning. The top of the mountain simply wasn’t there, replaced instead by a huge column of ash. The area we had worked in the day before was covered by a landslide. As we circled, I realised there was no hope for Dave. It was pure chance that put him, rather than me, out there on that day.
You can rarely pinpoint when a volcano will erupt. Our team from the US Geological Survey had been studying Mount St Helens for two months as it had been showing signs of activity. I was quite familiar with the volcano, because I grew up in the area. As a kid, I went boating on Spirit Lake to the north. I climbed the mountain when I was older. Back then, the summit was a sharp point, with glaciers all around it.
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A new bulge had appeared under the glacier on the north side, and we needed to find out what was happening. I remember feeling extreme curiosity, excitement and a little anxiety: every time I stood below the volcano, I knew something could happen at any time.
It turned out that magma was moving into a chamber inside the volcano, shoving out the entire north side at the unprecedented rate of 1.5 metres or more every day – so fast that at first we thought our measurements were cuckoo. It quickly became evident that this couldn’t continue indefinitely.
On 18 May there was an earthquake and a landslide as the bulge collapsed. The whole side of the mountain slid away, triggering the eruption seconds later as immense pressure was released. We were expecting a normal, vertical eruption, but instead the volcano erupted horizontally out of the newly created vent. It was a huge surprise: we didn’t know that the failure of the side of a volcano could set off an eruption. It seems obvious now, but until then it wasn’t generally accepted.
The landslide was the largest in recorded history. And the eruption blasted out thousands of tonnes of pyroclastic material – a surge of superheated ash, gas and rocks. Meanwhile, the heat melted the glaciers and snow, creating a semi-liquid mudslide, known as a lahar. All this material travelled down the mountain, destroying everything in its path.
Dave was the only person from the USGS in the field at the time. Two days before, we had talked about who was going to occupy the Coldwater II monitoring station – the closest in, about 10 kilometres from the mountain. Harry Glicken’s two-and-a-half week stint was coming to an end and I was scheduled to take the next few days, but I had a visitor so I asked Dave if he could be at the observation post on Saturday night, and I would take over on Sunday. He reluctantly agreed.
We’d previously abandoned Coldwater I monitoring station as it was too low to be safe from lahars and avalanches. Coldwater II was further away, and on a ridgecrest, and with our knowledge of volcanoes at the time we considered it relatively safe. I think Dave was uncomfortable going there because a few years before he’d seen first-hand the damage caused to a research cabin by pyroclastic flows from Augustine volcano in Alaska.
Ultimately, Dave accepted the risk as part of the job. We decided the scientific benefits of observing this unprecedented volcanic deformation from that location, and the answers it might provide, outweighed the risks.
In hindsight, of course, I’m not sure we were right. When the volcano erupted on Sunday morning, . The pyroclastic surge raced towards Coldwater II at about 300 miles per hour. It would have reached him in about 60 seconds.
Fifty-six others also died as a result of the eruption, and we wanted to learn from it to save lives in the future. The ability to predict eruptions has vastly improved since 1980, but even before St Helens we felt that it was achievable. The problem is each volcano is different and at the time we didn’t know what to expect at even one volcano, much less all the rest. We were all excited by the eruption and the challenge of figuring out what had happened so that those lessons could be applied elsewhere.
St Helens remained active for many years after the 1980 eruption and became a training ground for a lot of scientists. For the first three or four years, we were constantly testing new ideas and techniques – with some success. For example, my work focused on the dome of lava that builds up in the crater: we realised that the dome grew very slowly at first, but this accelerated several weeks before a major event. Knowing this enabled us to anticipate eruptions with close to 100 per cent accuracy. We also showed how seismology could be used to predict activity. St Helens spurred volcanology because so much happened that was laid bare for all to see. And because it took place in the US, we were able to marshal a lot of resources to measure the volcano before, during and after the explosion.
But knowledge doesn’t always translate into practice. In 1985, the Nevado del Ruiz volcano in Colombia, which, like St Helens, was topped with glaciers, began a series of eruptions after months of low-level activity. After an initial, minor blast, the volcano went quiet for a few hours, so the authorities abandoned the evacuation – against the advice of Colombian scientists, who knew the risk of lahars because of what had happened at St Helens.
Soon after, a more serious eruption and glacial melt created a huge lahar that sped down several valleys, killing 23,000 people in the town of Armero. The local priest had told everybody they would be OK, and there had been a big football game on television that evening, and it was stormy outside. Who wants to evacuate in those circumstances?
“When the volcano erupted, Dave was in the heart of the blast zone”
One good thing that came out of the Colombian disaster is the US Volcano Disaster Assistance Program. It uses the knowledge we had built up to provide assistance, training and monitoring at active volcanoes around the world. It has been very successful at saving lives ever since, and its roots lie in our work at St Helens. That may, in the end, be the eruption’s most important outcome.
The area I grew up in is different now. The eruption buried about 500 square kilometres of forest under rock and ash 50 metres deep. Spirit Lake became a dead zone filled with volcanic material and thousands of trees torn from the hillsides. It is still recovering.
I knew three people who died at St Helens: Dave, another colleague Jim Fitzgerald, and Harry Truman, who my family used to rent boats from on Spirit Lake. All of us working at St Helens were motivated not only by the science, but also by our losses. It was a bittersweet period, and I often think of Dave. We were hoping what we were doing would enable better monitoring, mitigate disasters and save lives. And, for the most part, it has.
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Don Swanson is a research geologist at the US Geological Survey’s Hawaiian Volcano Observatory and an affiliate professor at the University of Hawaii at Manoa
This article appeared in print under the headline “The day I should have died”
