Officials and residents are cautiously optimistic that Mauna Loa’s first eruption in nearly 40 years will be minimally disruptive.
Mauna Loa, the largest active volcano in the world, began erupting late Sunday night, and the U.S. Geological Survey’s Hawaiian Volcano Observatory reported lava was inside Moku‘aweoweo, the volcano’s summit caldera, at about 11:30 p.m.
By 6:30 a.m. Monday morning, HVO reported that lava flows had broken out of three fissures that formed on the volcano’s northeastern flank.
As of 1:30 p.m. Monday, there was no more active lava within the caldera, and only the lowest-altitude of the three fissures was producing lava. That fissure — dubbed Fissure 3 — produced a lava flow moving parallel with the Northeast Rift Zone. The flow was more than 10 miles away from the Daniel K. Inouye Highway. Flows from Fissures 1 and 2 stalled about 11 miles from the highway.
Mayor Mitch Roth said Monday that so far the eruption seems to be following the best scenario.
“We’ve been told that the lava is heading in the best possible direction, which is away from our communities,” Roth said in a statement, adding that the lava flow presented no imminent threat to any Big Island community.
During a press conference later Monday, HVO Scientist In Charge Ken Hon said the location of the lava suggests that it could eventually begin flowing in the general direction of Hilo, but added that it will take about a week before its direction will be apparent. He added that the eruption could mirror its previous eruption, in 1984, with the lava becoming more viscous and slow-moving over time.
Hon said the lava is heading toward the Big Island “saddle” — the large area between Mauna Loa and Maunakea — which he said is preferable because of the lack of human habitation and the relatively flat slopes that will further slow the flows. He added that the nearby Pohakuloa Training Area’s facilities are outside of the current predicted path for the flows, and that only the access road to the Mauna Loa Observatory is under potential threat.
A statement from the Pohakuloa Training Area stated that the U.S. Army is monitoring the situation, but there are no troops training at PTA, and there is no immediate threat to facilities or personnel.
Hon said Mauna Loa eruptions are historically most energetic within the initial week or two, and “calm down” afterward. While he said there is no guarantee that this eruption will be the same, he added that he is not expecting it to last as long as the 2018 Kilauea eruption, which went on for four months and destroyed nearly 700 homes.
“As far as we know in any historic precedents, there has never been an eruption of Mauna Loa that activated both rift zones at the same time,” Hon said. “So, we presume at this point that all of the future activity is going to be on the Northeast Rift Zone of Mauna Loa and not on the Southwest Rift Zone, so the residents in that area do not have to worry about lava flows.”
Those communities include places like Ocean View and Pahala, where the steep southwestern slopes of Mauna Loa would accelerate any lava flows significantly. At an Ocean View community meeting in October, HVO scientists reported that lava flows in the Southwestern Rift Zone can reach the ocean within three hours.
Before it was clear where the lava was headed on Monday, residents of the island’s southern communities worked to prepare for disaster.
Cristen Navarro, an employee at a Naalehu gas station, said cars lined up and down the street as people bought gas and water in case of an eventual evacuation.
“It got to the point where we’ve had to limit it to like one thing of toilet paper per person,” Navarro said. “We opened at 4:30 a.m., and it’s been really busy all day.”
Other Pahala residents took a relaxed view of the situation. Resident Fidel Agustin said he had no reason to be afraid — “If you take care of the aina, then it will take care of you,” he said — while Julia Neal, owner of Pahala Plantation Cottages, said she was glad the weeks of waiting for the eruption to start are finally over.
“It’s kind of a relief that it’s happening and we’re not waiting for it to happen,” Neal said.
While the county made no evacuation orders, it did open a pair of emergency shelters in Pahala and Kailua-Kona in response to reports of people evacuating on their own.
Red Cross Shelter Manager Warren White said the Pahala shelter has cots for about 200 people, but added that it could be relocated to a different location depending on where the lava goes.
“It’s up to (Hawaii County) Civil Defense,” White said. “If it doesn’t get used, then at least it was a good drill for us.”
Civil Defense Administrator Talmadge Magno said the county would make a decision about whether to keep the shelters open based on a review of their populations Monday afternoon.
Meanwhile, Hawaii Volcanoes National Park, where Mauna Loa summit is located, made some closures following the eruption.
Mauna Loa Road has been closed to vehicles, while the summit, cabins and other high-elevation areas have been closed since early October.
Park spokeswoman Jessica Ferracane said the Federal Aviation Administration has temporarily restricted flights within a five-nautical-mile radius around the Mauna Loa summit.
But while the lava itself isn’t posing an immediate threat to people, the state Department of Health warned residents that air quality conditions could worsen as a result and advised people to avoid heavy breathing or opening doors and windows if volcanic fumes or ash levels increase. Hon said models predict that sulfur dioxide and other gases could be blown northward and toward Maui.
Since the mid-19th century, Mauna Loa’s Northeast Rift Zone has erupted eight times: in 1843, 1852, 1855-1856, 1880-1881, 1899, 1935-1936, 1942, and 1984. Lava flows from the Northeast Rift Zone can travel in north, west, northwest, south, and southwest directions.
The AP contributed to this report.
Email Michael Brestovansky at mbrestovansky@hawaiitribune-herald.com.