WHITE plumes of acid and extremely fine shards of glass have billowed into the sky over Hawaii as molten rock from Kilauea volcano poured into the ocean.

Authorities have warned the public to stay away from the toxic steam cloud, which is formed by a chemical reaction when lava touches seawater.

Further upslope, lava continued to gush out of large cracks in the ground that formed in residential neighbourhoods in a rural part of the Big Island.

The molten rock formed rivers that bisected forests and farms as it meandered towards the coast.

The rate of sulphur dioxide gas shooting from the ground fissures tripled, leading Hawaii County to repeat warnings about air quality.

At the volcano’s summit, two explosive eruptions unleashed clouds of ash and winds carried much of the ash towards the south west.

Joseph Kekedi, an orchid grower who lives and works about 5km from where lava dropped into the sea, said luckily the flow did not head towards him.

He said residents cannot do much but stay informed and be ready to get out of the way.

“Here’s nature reminding us again who’s boss,” Kekedi said.

Scientists said the steam clouds at the spots where lava entered the ocean were laced with hydrochloric acid and fine glass particles that can irritate the skin and eyes and cause breathing problems.

The lava haze, or “laze”, from the plume spread as far as 24km west of where the lava met the ocean on the Big Island’s southern coast.

It was just offshore and running parallel to the coast, said US Geological Survey scientist Wendy Stovall.

Experts said the acid in the plume was about as corrosive as diluted battery acid. The glass was in the form of fine glass shards. Getting hit by it might feel like being sprinkled with glitter.

“If you’re feeling stinging on your skin, go inside,” Stovall said.

Authorities warned that the plume could shift direction if the winds changed.

The Coast Guard said it was enforcing a safety zone extending 300m around the ocean entry point.

Coast Guard Lt Cmdr John Bannon said in a statement that “getting too close to the lava can result in serious injury or death”.

Governor David Ige told reporters in Hilo that the state was monitoring the volcano and keeping people safe.

He said he was thankful that the current flows were not risking homes and hoped it would stay that way.

Kilauea has burned some 40 structures, including two dozen homes, since it began erupting in people’s back gardens in the Leilani Estates neighbourhood on May 3. Some 2000 people have evacuated their homes, including 300 who were staying in shelters.

In recent days, the lava began to move more quickly and emerge from the ground in greater volume.

Scientists said that is because the lava that first erupted was magma left over from a 1955 eruption that had been stored in the ground for the past six decades.

The molten rock that began emerging over the past few days was from magma that has recently moved down the volcano’s eastern flank from one or two craters that sit further upslope – the Puu Oo crater and the summit crater. The new lava is hotter, moves faster and has spread over a wider area.

Scientists say they do not know how long the eruption will last.

The volcano has opened more than 20 vents, including four that have merged into one large crack.

This vent has been gushing lava high into the sky and sending a river of molten rock towards the ocean at about 280m per hour.

Hawaii tourism officials have stressed that most of the Big Island remains unaffected by the eruption.