Hawaii volcano. (Photo: Kevan Kamibayashi/ US Geological Survey via AP)
A Hawaii volcano that sputtered lava for a week, forced around 2 000 residents to evacuate, destroyed some two dozen homes and threatened a geothermal plant, now threatens to blow its top in the coming days or weeks.
Experts fear it could hurl ash and boulders the size of refrigerators miles into the air.
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.
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"If it goes up, it will come down," says Charles Mandeville, volcano hazards coordinator for the US Geological Survey. "You don't want to be underneath anything that weighs 10 tons when it's coming out at 193 kph."
Eruption could affect flights
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 22:00 on Thursday, 10 May, because of the risks.
"We know the volcano is capable of doing this," Mandeville says, 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."
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He would not estimate the likelihood of such an explosion, but says 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 it happens, a summit blast could also release steam and sulfur dioxide gas.
Destruction to property
Kilauea has destroyed 36 structures — including 26 homes — since 3 May, when it began releasing lava from vents about 40 kilometres east of the summit crater. Fifteen of the vents are now spread through the Leilani Estates and Lanipuna Gardens neighborhoods.
Hawaii Gov. David Ige says crews at a geothermal energy plant near the lava outbreak accelerated the removal of stored flammable fuel as a precaution. The Puna Geothermal Venture plant had about 189 270 litres of pentane. It was removed early Thursday.
Barbara Lozano, who lives within a mile of the plant, says she would have thought twice about buying her property if she had known the risks.
"Why did they let us buy residential property, knowing it was a dangerous situation? Why did they let people build all around it?" she asked.
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Avani Love, 29, moved to the Big Island about a month ago from Maui with her four children. They evacuated their home on 3 May, 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 says "When you have that, it's Pele's way of clearing house and restoring the place. There's beauty and also darkness."
No one lives in the immediate area of the summit. Communities around 3 kilometres away may be showered by pea-size fragments or dusted with nontoxic ash, says Tina Neal, scientist-in-charge at the Hawaii Volcano Observatory.
What could happen is not an eruption of volcanic gases but mostly trapped steam from flash-heated groundwater released like in a kitchen pressure cooker, with rocks, says volcanologist Janine Krippner of Concord University in West Virginia.
Lava levels in the lake dropping
The problem is the lava lake at the summit of Kilauea is draining fast, about 2 metres per hour, Mandeville says.
In little more than a week, the top of the lava lake has gone from spilling over the crater to almost 295 metres below the surface as of Thursday morning, Mandeville says. The lava levels in the lake are dropping because lava is spewing out of cracks elsewhere in the mountain, lowering the pressure that filled the lava lake.
"This is a huge change. This is three football fields going down," Mandeville says.
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 says.
At the current rate of change, that is about six or seven days away.
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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 1 200 Celsius 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 9 kilometres into the sky, for a couple of weeks. If another blast happens, the danger zone could extend about 5 kilometres around the summit, land all inside the national park, Mandeville says.
The small, aptly named town of Volcano, Hawaii, population 2 500, is about 4.83 kilometres from the summit. Janet Coney is office manager of the Kilauea Lodge, an inn and restaurant. She says USGS officials told her lodge employees probably won't have to worry about rocks raining down on them, but they might experience falling ash.