Hawaii's Kilauea volcano could soon send boulders and ash shooting out of its summit crater. That kind of explosive eruption was last displayed by the volcano nearly a century ago.

This eruption could occur even the volcano continues to splatter and ooze lava out of its eastern flank into a residential area.

Scientists said Wednesday the risks of an explosive summit eruption will rise in coming weeks as magma drains down the flank of the volcano.

Hawaii Gov. David Ige says a geothermal energy plant near the lava outbreak would remove its storage of a flammable gas called pentane by the end of the day Thursday.

He says it would be "very hazardous" if a volcanic vent were to open under the facility where the fuel is stored.

Authorities ordered nearly 2,000 residents to leave two communities in the mostly rural district of Puna on Hawaii's Big Island last Thursday. Some ignored the order and stayed to watch over their property.

But on Tuesday, the emergence of the two new vents prompted Hawaii County to issue a cellphone alert ordering stragglers in Lanipuna Gardens to get out immediately. Police followed up with personal visits.

"There were a number of people at their residences," Talmadge Magno, the administrator for Hawaii County Civil Defense, said at a news briefing. There was no sign of holdouts in Lanipuna afterward, he said.

Edwin Montoya, 76, had planned to stay to care for animals and keep looters away from his family's property in neighboring Leilani Estates. But he was forced to evacuate after the new fissures emerged, including one just a mile away.

"I'm in my truck right now on my way up the road," he said. "The police came down here and made me."

Both communities are in a forested, remote part of the Big Island on the eastern flank of Kilauea volcano, which has been erupting continuously since 1983.

In recent years the volcano has mostly released lava in hard-to-reach areas inside a national park or along the coastline. But last week, vents popped open and released lava, gas and steam inside residential neighborhoods.

There's no indication when the eruption might stop, or how far the lava might spread.

There were about 1,700 residents in Leilani Estates and a few hundred in Lanipuna Gardens before last week.

Andrew Nisbet evacuated last week and has no idea what has happened since.

"My home is right in the line of the major breakouts so maybe, maybe not." he said Monday during a community meeting.

Authorities urged Scott Wiggers to evacuate, but he refused.

"I'm in the safest part in the subdivision. There's no threat to my house whatsoever," said Wiggers, a tour guide.

Wiggers said he wasn't leaving his home on the outskirts of the evacuation zone because he worried that if he did, he wouldn't be able to get back in. But he's prepared in case the situation takes a turn.

"I am packed. My truck is loaded. I'm not a dumb-dumb. If I see a threat, I'm out of here," he said.

Officials warn that lava could flow downhill and burn areas that are not currently in danger, and toxic volcanic gas could kill people, especially the elderly and those with breathing problems.

Hawaii Gov. David Ige told evacuees he has called the White House and the Federal Emergency Management Agency to tell officials that he believes the state will need help to deal with the volcano on the Big Island.

There are 14 lava-and-gas producing fissures in Leilani Estates, after the two new ones formed Tuesday. But the flow of lava is not constant.

A total of 36 structures, including 26 confirmed homes, have been destroyed. Aerial surveys cannot make out whether some of the structures are homes or other types of buildings.

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