Scientists note that as long as people stay out of closed areas of a national park around the volcano, the possible explosion won’t be deadly.
But the added threat of an explosive eruption could ground planes at one of the Big Island’s two major airports and pose other dangers. The national park around the volcano announced that it would close indefinitely starting 10 p.m. Thursday because of the risks.
“We know the volcano is capable of doing this,” Mandeville said, citing similar explosions at Kilauea in 1925, 1790 and four other times in the last few thousand years. “We know it is a distinct possibility.”
He would not estimate the likelihood of such an explosion, but said the internal volcanic conditions are changing in a way that could lead to a blast in about a week. The volcano’s internal plumbing could still prevent an explosion.
If an explosion does happen, a summit blast could also release steam and sulfur dioxide gas.
Kilauea has destroyed 36 structures — including 26 homes — since May 3, when it began releasing lava from vents about 25 miles east of the summit crater. Fifteen of the vents are now spread through the Leilani Estates and Lanipuna Gardens neighborhoods.
Hawaii Gov. David Ige said crews at a geothermal energy plant near the lava outbreak accelerated the removal of stored flammable fuel as a precaution on Thursday. The Puna Geothermal Venture plant had about 50,000 gallons of pentane.
No one lives in the immediate area of the summit but communities up to two miles away could be showered by pea-size fragments or dusted with nontoxic ash, said Tina Neal, scientist-in-charge at the Hawaii Volcano Observatory.
The problem is the lava lake at the summit of Kilauea is draining fast, about 6.5 feet per hour, Mandeville said.
In little more than a week, the top of the lava lake has gone from spilling over the crater to almost 970 feet below the surface as of Thursday morning, Mandeville said. The lava levels in the lake are dropping because lava is spewing out of cracks elsewhere in the mountain, lowering the pressure that kept the lava lake filled.
“This is a huge change. This is three football fields going down,” Mandeville said.
The fear is that it will go below the underground water table — another 1,000 feet further down — and that would trigger a chain of events that could lead to a “very violent” steam explosion, Mandeville said.
At the current rate of change, that is about six or seven days away.
Once the lava drops, rocks that had been superheated could fall into the lava tube. And once the lava drops below the water table, water hits rocks that are as hot as almost 2,200 degrees and flashes into steam. When the water hits the lava, it also steams. And the dropped rocks hold that steam in until it blows.
A similar 1924 explosion threw pulverized rock, ash and steam as high as 5.4 miles into the sky, for a couple of weeks. If another blast happens, the danger zone could extend about 3 miles around the summit, land all inside the national park, Mandeville said.
The small, aptly named town of Volcano, Hawaii, population 2,500, is about three miles from the summit.
Avani Love, 29, moved to the Big Island about a month ago from Maui with her four children. They evacuated their home on May 3, and only found out it was destroyed when a relative went back to get her personal belongings.
While saying she’s sad to have lost her home, she also feels a sense of renewal brought on by Pele, the Hawaiian volcano goddess, to correct overpopulation of the island.
“Everyone comes here,” she said. “When you have that, it’s Pele’s way of clearing house and restoring the place. There’s beauty and also darkness.”