Mauna Loa eruption prompts officials to warn of a worst-case scenario - USA TODAY

Mauna Loa, the largest progressive volcano successful the world, has begun to erupt in Hawaii, the U.S. Geological Survey and different authorities said, prompting officials informing people living connected Hawaii’s Big Island to beryllium acceptable successful the lawsuit of a worst-case scenario.

The eruption started precocious Sunday at astir 11:30 p.m. HST in Moku‘āweoweo, the acme caldera of Mauna Loa in Hawaii Volcanoes National Park, according to a USGS Hawaiian Volcano Observatory alert. The observatory said it was working intimately with exigency absorption partners.

The eruption had remained confined to the acme caldera aboriginal Monday, but USGS Volcanoes and the Hawaii Emergency Management Agency aboriginal reported immoderate overflowing connected the southwest portion. Shortly earlier 12:20 p.m. EST (7:20 a.m. HST) USGS Volcanoes announced the volcano's eruption had moved to the northeast rift zone, with lava flows heading downslope to the north. 

In a aboriginal update, USGS Volcanoes announced that the eruption successful the northeast rift portion was inactive ongoing but no lava was erupting from the southwest rift zone.

"We bash not expect immoderate eruptive enactment extracurricular the Northeast Rift Zone. No spot is astatine hazard currently," USGS Volcanoes said connected Twitter.

An eruption from the northeast means lava could travel towards Hilo, Hawaii, or different locations successful East Hawaii, but it could instrumentality the lava weeks oregon adjacent months to scope people. Lava emerging from a southwest rift portion could scope communities successful hours oregon days. 

USGS Hawaiian Volcano Observatory said the lava flows are not threatening immoderate adjacent communities downhill astatine this time. Still, volcanic gas, good ash and Pele's Hair, bladed strands of volcanic glass, could "be carried downwind."

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The Observatory added that it appears the eruption volition stay successful the northeast rift zone. 

"The displacement of the erupting country into the northeast rift portion takes the hazard into overmuch little steep terrain," Hawaii Emergency Management Agency tweeted pursuing the development.

"Eruptions connected steep terrain determination rapidly downhill portion lava is inactive precise blistery and liquid. Shallow slopes let it to chill much arsenic it moves downhill, slowing its advancement adjacent more. NE rift portion eruptions whitethorn instrumentality weeks oregon months to scope the sea, vs. hours connected steeper slopes."

While adjacent communities are not threatened astatine this time, shelters have been opened arsenic a precaution in Kailua-Kona and Pahala.

Lifelong Big Island nonmigratory Bobby Camara, who lives successful Volcano Village, said everyone crossed the land should support way of the eruption. He said he’s seen 3 Mauna Loa eruptions successful his beingness and stressed the request for vigilance.

“I deliberation everybody should beryllium a small spot concerned,” helium said. “We don’t cognize wherever the travel is going, we don’t cognize however agelong it’s going to last.”

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The USGS encouraged residents who are perchance astatine hazard from Mauna Loa lava flows to reappraisal their eruption preparations, noting that past events amusement lava flows tin "change rapidly." The Hawaii County Civil Defense also has a Mauna Loa Lava Inundation Zones map for reference.

"If the eruption remains successful Moku‘āweoweo, lava flows volition astir apt beryllium confined wrong the caldera walls. However, if the eruptive vents migrate extracurricular its walls, lava flows whitethorn determination rapidly downslope," the USGS Hawaiian Volcano Observatory wrote successful its Sunday nighttime alert.

Portions of the Big Island were also nether an ashfall advisory Monday morning, though it ended later successful the day. Officials cautioned people with respiratory illnesses oregon sensitivities to instrumentality precautions, adjacent aft the advisory was lifted. 

The Hawaii Department of Health advised residents and visitors to hole for aerial prime impacts owed to the eruption connected Monday afternoon. As of 7 p.m. EST, the aerial prime remained normal, according to the section of health.

But the section warned that "the eruption could origin vog conditions, ash successful the air, and levels of sulfur dioxide to summation and fluctuate successful assorted areas of the state."

With conditions changing rapidly, the section advised radical to instrumentality precautionary measures, including reducing outdoor vulnerability and wearing masks if extracurricular to limit inhalation of hazardous particulates.

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Because of a spike successful earthquakes astatine the acme of Mauna Loa, scientists person been connected alert for an eruption. With Sunday night's eruption, the volcano alert level for Mauna Loa has accrued from advisory to warning, and its aviation alert upgraded from yellow to red.

Mauna Loa, which past erupted successful 1984, rises 13,679 feet supra oversea level. It's among the 5 volcanoes that marque up Hawaii's Big Island.

Mauna Loa sits immediately northbound of Kilauea volcano, which is besides erupting – but with a "watch" volcano alert level and orange aviation alert, according to the USGS Hawaiian Volcano Observatory. A 2018 Kilauea eruption destroyed 700 homes and sent lava into the ocean.

Because Mauna Loa is taller than Kilauea, experts note, it could unreserved down immoderate of its hillsides faster due to the fact that of steeper slopes – perchance successful a substance of hours.

Contributing: Thao Nguyen, USA TODAY; The Associated Press