Michelle Coombs, of the Hawaiian Volcano Observatory, said the explosion about 4:15 a.m. at Halemaumau Crater was powerful but short-lived, which meant levels of ash dropping on surrounding communities were not as significant as officials had feared.
But she stressed that additional steam-induced eruptions are possible.
“It’s a real dynamic situation up there,” Coombs told reporters Thursday. “The one this morning is definitely the biggest we’ve seen so far.”
After the explosion, the National Weather Service issued an ashfall advisory for parts of the Big Island, saying ash accumulation less than one quarter of an inch was possible through at least 6 p.m. But the advisory was cancelled by about 11:30 a.m., thanks in part to rain.
Coombs said the eruption Thursday morning was “consistent” with a steam-induced explosion — lava interacting with the water table. Geologists have been warning about such an explosion for days, and have said previous thick emissions from the crater were likely due to rockfalls or gas explosions.
Despite the size of the explosive eruption, a number of nearby residents said they didn’t see or hear anything. Scientists say that’s because it was dark at the time and because the explosion happened deep in the crater.
But a number of communities did report light ashfall, much of which was mixed with rain.
In Hilo, resident Pua’ena Ahn said the ash plumes have left him with itchy, watery eyes and skin irritation.
On Thursday afternoon, Gov. David Ige visited the Big Island to reassure residents.
“It’s really heartwarming to see the support that is coming from all over the state,” Ige said.
Volcanic activity at the summit has been ticking up since last week as lava levels continue to drop.
On Wednesday, at least 125 shallow quakes rattled Kilauea’s summit and neighboring communities, causing minor damage to roads and buildings. The strongest quake in the area was a magnitude 4.4, and dozens more have been upwards of magnitude 3.
Also on Wednesday, Hawaiian Volcano Observatory said rocks up to 2 feet wide were hurled from the crater to a parking lot hundreds of yards away.
A day earlier, rockfalls triggered large ash emissions from the crater.
Scientists have warned that eruptions at the summit could send heavy ashfall across communities near the summit and toss boulders “the size of cows” as far as a half a mile.
Given the threat, Hawaii Volcanoes National Park remains closed, and civil defense officials are urging those who live near the crater to remain vigilant.
The news comes amid worsening air quality conditions on the Big Island, and as civil defense authorities continue to respond to Kilauea’s ongoing eruptions in lower Puna, where thousands of people remain under mandatory evacuation orders.
In Pahoa on Thursday, thick volcanic haze and high sulfur dioxide levels prompted several schools to close and prompted health warnings.
Emissions at Halemaumau Crater have been high for days. On Tuesday, thick, dark columns of ash poured from the crater, extending up to 12,000 feet above sea level and dropping ash as far as 18 miles downwind.
Dramatic images showed large plumes looming over the Volcano Golf Course. In Pahala, residents reported heavy vog and significant ashfall.
The last time steam-induced eruptions happened at Halemaumau Crater was nearly a century ago, when flying debris killed one and left a layer of ash over homes and cars. In 1924, explosive events at the summit lasted for two and a half weeks and ash reached as high as 20,000 feet above sea level.
Scientist say they’re using the 1924 event as something of a baseline, using it to determine how long this volcanic event might last and how strong eruptions could be.
This story will be updated.