Residents of the Big Island were warned to take shelter from the ash fallout as toxic gas levels spiked in a small southeast area where lava has burst from the ground since the eruption began two weeks ago, authorities said.
The wind could carry Kilauea’s ash plume as far as Hilo, the Big Island’s largest city and a major tourism centre, the County of Hawaii Civil Defense warned in an alert.
“Protect yourself from ash fallout,” it said.
Kilauea is one of the most active volcanoes in the world and one of five on Hawaii's Big Island.
It started erupting on May 3, prompting some 2,000 people to flee from their mountainside homes.
Geologists said the 4:15am explosion was likely the first in a series of steam-driven explosions last seen 1924, rather than “the big one” that nervous residents had been fearing.
A spike in toxic sulphur dioxide gas closed schools around the village of Pahoa, 40 km east of the volcano, where fissures have destroyed 37 homes and other structures and forced about 2,000 residents to evacuate, health officials said. National guard troops were forced to put on gas masks at a nearby road intersection, according to a Reuters reporter.
USGS geologists and staff were evacuated from the Kilauea summit shortly before the blast and a webcam showed a grey plume of ash and chunks of magma known as pyroclasts that showered the volcano’s slopes.
Tall but small
But the eruption was short-lived, said Coombs who called it “a big event that got people’s attention, but did not have widespread impact”.
“Tall but small,” she said of Thursday’s plume.
An aviation red alert was in effect due to risks that ash could be carried into aircraft routes and damage jet engines, USGS said. Passenger jets generally cruise at around 30,000 feet, the height of Thursday’s plume.
Pahoa fire station on Thursday morning recorded a “red level” of sulphur dioxide, meaning it would cause choking and an inability to breathe, Fenix Grange of the Hawaii Department of Health told a news conference in Hilo.
“If it’s red, it’s get out of Dodge,” She said. “We’re trying to create a ring around sulphur dioxide so we can protect people.”
Lava has destroyed at least 37 homes and other structures in communities near Pahoa, in the southeast area of the island, and forced around 2,000 people to evacuate their homes.
Across the Big Island, home to 200,000 residents, people were encouraged to avoid driving in ashfall areas, as the powdered rock makes roads slippery, and not go outdoors unless necessary.
“Not a good day to go out running,” said Fenix. “People want to stay put and stay behind closed doors.”
Locals in communities near the volcano hit by ashfall such as Volcano, Pahala and Naalehu were to be issued one ash mask per family member, according to a civil defence message.
Geologists had warned explosive eruptions could begin once Kilauea’s falling lava lake descended below the water table, allowing water to run on to the top of the lava column and create steam-driven blasts.
“We can expect similar events in the future to continue as lava continues to interact with water,” Coombs said about Thursday’s eruption.
More powerful explosions have the potential to hurl “ballistic blocks” the size of refrigerators across a distance of more than one kilometre and shoot pebble-sized projectiles and debris up to a dozen miles, the USGS has warned.