Members of the Arizona National Guard answered the call and ventured into some unsafe areas on the Big Island of Hawaii after entire neighborhoods witnessed cracks and fissures from the Kilauea volcano.
There's a lone webcam operating at the Hawaii Volcano Observatory's evacuated observation tower. Whereas St. Helens sits along the geologically active boundary of the Pacific Plate, Kilauea and the other Hawaiian volcanoes are powered by inside the Earth's mantle.
The scientific advisory board said in a separate statement: "At any time, activity may again become more explosive, increasing the intensity of ash production and producing ballistic projectiles near the vent".
PAHOA, HI - MAY 16: Eruptive activity from the Kilauea volcano continues in the vicinity of fissure 17 with cooling lava (center and center left) on Hawaii's Big Island on May 16, 2018 in Pahoa, Hawaii. All these variables are hard to predict.so there might not even be a big one.
This was the scene that greeted Arizona National Guard members when they arrived on the Big Island two weeks ago.
Thursday's explosion sent an ash plume around 30,000 feet high.
"We had prepared for the event", he said.
Residents of the Big Island were warned to take shelter from the ash as toxic gas levels spiked in a small southeast area where lava has burst from the ground during the two-week eruption.
Historically, Kilauea's rumblings have not been as deadly as other volcanoes around the world, said Steve Malone, an emeritus research professor of volcanology at the University of Washington in Seattle.
"So a big event that got people's attention but not with widespread impacts", Michelle Coombes said. Michael O'Meally, 23, who lives in Aiea and works in sales in Waikiki, said a friend who works at a Ko Olina resort told him she has fielded several calls from concerned guests.
This week's activity is just one of 61 recorded eruptions in the volcano's cycle.
Residents with respiratory problems had already been warned to stay indoors in the area on Thursday following an early morning ash cloud eruption at the Halemaumau Crater.
As the molten rock dropped below the level of the water table, it's likely that water in the surrounding rock began pouring into the vacated chamber - much the way water rushes to fill a recently dug well, said Charlotte Rowe, a geophysicist at Los Alamos National Laboratory.
What is happening at Kilauea is fundamentally is dissimilar from that 1980 eruption, experts told. More than 30 people were killed when a 2014 phreatic eruption at Japan's Mount Ontake caught them unaware near the summit.
Their hope is to pinpoint warning signs that could be used to predict phreatic eruptions in Hawaii and elsewhere.