37 years later: Scientists reflect on the catastrophic 1980 Mount St. Helens eruption

By Ashley Williams, AccuWeather staff writer

May 16,2017, 8:41:12PM,EDT

 

 

Mount St. Helens in Washington spews smoke, soot and ash into the sky in April, 1980. (AP Photo/Jack Smith)

May 18, 2017, marks 37 years since Mount St. Helens erupted in Washington State, killing 57 people.
The violent eruption of the Cascade Range’s most active volcano had been its first major event in over a century.
A series of small earthquakes at the volcano had begun a couple of months prior.
“On the afternoon of March 20, [1980], a 4.0-magnitude earthquake took place at Mount St. Helens, and I immediately recognized that as something of interest,” said Dr. Stephen Malone, research professor emeritus at the University of Washington.
Malone studied volcano seismology as a research assistant professor in the university’s geophysics program in 1980.
In the weeks leading up to the May 18 eruption, researchers collaborated with volcano hazard experts at the U.S. Geological Survey (USGS) to monitor Mount St. Helens.
According to Malone, the volcano’s first eruption occurred on March 27.
For the next two months, researchers continued to monitor the volcano’s earthquake activity, which seemed to decrease in terms of numbers of events.
“However, some of the earthquakes that were occurring were even bigger than the ones that had occurred before,” said Malone.
“So, we were convinced this was not over,” he said.
At 8:32 a.m. on May 18, an earthquake measuring 5.1 on the Richter scale shook the north face of Mount St. Helens, causing it to collapse and trigger an avalanche of rock debris.
According to the Cascade Volcano Observatory (CVO), the debris avalanche was the largest on Earth in recorded history.
The CVO calculated the avalanche’s total volume at 3.3 billion cubic yards – equal to one million Olympic swimming pools.
The blast measured at a VEI 5 on the Volcanic Explosivity Index, which is a relative measure of the explosive activity of volcanic eruptions.
Despite the earthquake activity present at the volcano in the months leading up to the massive eruption, the events that occurred on May 18 were not predicted.

A car is shown submerged in ash in this May 20,1980 from Mount St. Helen eruption in Washington State. (AP Photo)

“My hope had been that we would see some change in the earthquake activity, some additional number of events, types of events… something that would give us a warning before an eruption occurred,” said Malone.
Unfortunately, he said, this did not occur.
The explosion and avalanche devastated nearly 150 square miles of forest, but surprisingly, not all lifeforms were lost in the destruction.
Only 2 percent of the landscape influenced by the blast had all life obliterated, said Charlie Crisafulli, research ecologist and lead Mount St. Helens researcher at the Pacific Northwest Research Station.
“In that 2 percent, that arguably makes the most interesting and compelling place to study, to see where life is starting from scratch,” said Crisafulli, who began studying the volcano in the weeks following the catastrophic eruption.
“We’ve learned that the single most important factor influencing how ecosystems respond following a disturbance is what is left behind,” he said.
The 1980 blast occurred in springtime while Mount St. Helens remained covered in snow, a factor that protected some organisms and even entire ecosystems from the blast.
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Had the eruption occurred two months later during summer, the ecological consequences would have been different, said Crisafulli.
“The [recovery] process may have taken decades longer based on what we saw based on a May eruption,” he said.

Steam rises from the crater of Mount St. Helens as seen from Johnston Ridge in this March 9,2005, file photo in Mount St. Helens, Washington. (AP Photo/Ted S. Warren, file)

Now, decades later, the Mount St. Helens landscape has evolved from gray to green but still bears no resemblance to how it appeared before the 1980 eruption.
“Our ability to forecast eruptions improves every time we monitor one of these,” said Dr. Weston Thelen, research geophysicist at the Cascades Volcano Observatory.
Advancements in technology since 37 years ago have allowed for scientists to better predict future volcanic activity.
"We have more seismometers on the cone," said Thelen.
Seismometers are very sensitive instruments that can detect movements of the Earth's surface.
"We [also] have better ways of detecting when the volcano is inflating or deflating," said Thelen.
“[These] provide us clues and give us a better idea of what’s going on in the volcano. That’s important for us to try to open up that forecasting window to longer and longer time periods,” he said.
As forecasting methods continue to improve, preparedness also remains at the forefront, as Washington State recognizes Volcano Preparedness Month throughout May.
Residents in the area have the opportunity to learn about volcano hazards and the appropriate steps to reduce potential impacts.