A resident of Leilani Estates takes photos of a lava flow near his home during ongoing eruptions of Hawaii’s Kilauea volcano, on May 8 2018. Picture: REUTERS
A resident of Leilani Estates takes photos of a lava flow near his home during ongoing eruptions of Hawaii’s Kilauea volcano, on May 8 2018. Picture: REUTERS

Los Angeles/Pahoa — A Hawaii volcano that has been oozing lava and burping steam for days may be gearing up for a huge eruption, scientists have warned, prompting the closure of Volcanoes National Park on Friday.

It was the newest threat from the Kilauea volcano, which began erupting last Thursday on the US state’s Big Island, the National Park Service said.

Scientists say lava levels in the crater were going down, meaning it might be clogging and building up for a mighty blast.

Movement of the molten rock opened space for lava at the summit to drain underground, reducing the height of a lava lake at the summit, US Geological Survey geophysicist Ingrid Johanson told the Los Angeles Times.

But as the lava lake levels fall below the groundwater table, water can start interacting with the magma, heating it up and creating steam, said US Geological Survey scientist Donald Swanson.

And if rocks fall from the walls surrounding the magma in the volcano, the rocks can form a dam.

And then, if the steam built pressure, "it can eventually burst out in an explosion", Swanson said.

Scientists estimate that the lava could interact with the groundwater by the middle of May.

No one has died, but the flowing lava has destroyed dozens of structures in an area called Leilani Estates.

Hundreds of people have been forced to evacuate their homes because of the lava and the threat of toxic fumes.

Residents were alerted on Thursday to rising levels of toxic gas from volcanic fissures and geologists warned that new areas east of the erupting Kilauea volcano may be at risk to lava bursting from the ground.

Hawaii County authorities sent a text message to residents in the southeast corner of the Big Island that a wind change would bring rising levels of sulphur dioxide gas, which is fatal if inhaled in large quantities.

"Due to decreasing tradewinds, residents are advised to monitor their sensitivity to increased levels of [sulphur dioxide]," the text message sent at 9.22am said.

Hawaii’s governor has warned that mass evacuations may be needed as more fissures open and spew lava and gas in semi-rural residential areas on the east flank of the volcano.

Authorities on Thursday completed the removal of highly flammable chemicals from a nearby power plant in the path of lava.

Geologists said Kilauea might be entering a phase of explosive eruptions not seen in nearly 100 years that could hurl "ballistic blocks" weighing up to 12 tonnes for 800m, shoot pebble-sized projectiles for kilometres, and dust downwind towns with volcanic ash and smog.

The Leilani Estates residential area remains in greatest danger, with 15 volcanic fissures so far having destroyed 36 structures, most of them homes, and forcing the evacuation of about 2,000 residents.

But as the eruption progresses, "other areas of the lower East Rift Zone may also be at risk", the Hawaiian Volcano Observatory said in its latest briefing.

Hawaii governor David Ige has requested federal disaster assistance as he said a mass evacuation of the lower Puna District, where Leilani Estates is located, would be beyond current county and state capabilities.

Surfing in the vog

Dustings of ash were expected downwind of Kilauea as summit earthquakes set off rockfalls into the lava lake and sent up plumes of steam, ash and smoke, the US Geological Survey said.

Local meteorologists said the change in prevailing winds could send Kilauea’s volcanic smog, or vog, northwest to Maui and other islands in Hawaii.

Surfers bobbing in the ocean off Kona on the west side of the Big Island complained of the smog that could be seen in a haze over the coast.

"Does that hat protect against vog?" one surfer was heard quipping to another about the floppy sun hat he was wearing.

In Pahoa, the nearest village to Kilauea, some schools remained closed after the area was hit by a 6.9 magnitude earthquake on Friday, the biggest since 1975.

The closures had added to a sense of disarray and ramped up stress levels, said gallery owner Amedeo Markoff.

"It’s like our version of a snow day — a lava day," joked Markoff.

Kilauea is one of the most active volcanos in the world and one of five on the island.

AFP, Reuters