Hawaii volcano spews 'ballistic blocks' into the sky in 'most energetic explosions yet'

A smouldering volcano in Hawaii has hurled large stones hundreds of metres and sent clouds of ash drifting over a number of communities.

Plumes of ash from Kilauea rose as high as 3,000 metres above sea level, dusting towns as far as 18 miles away with ash and air pollution known as “vog”. Shifting winds raised the possibility of more areas seeing ashfall.

Rockfalls within one of the volcano’s vents helped unleash more activity, geologists said, abruptly pushing out more ash. The volcano emitted dense “ballistic blocks” as large as 0.6 metres across, suggesting heightened activity driven by steam-powered explosions.

“These reflect the most energetic explosions yet observed”, the US Geological Survey said in a bulletin.

Authorities raised an aviation threat level from orange to red, cautioning that the clouds of ash could make flying difficult.

Kilauea’s eruption has forced open numerous fissures that have splattered out lava, putting residents on the defensive and prompting evacuations.

As of the morning, authorities said the lava flow from a newly active fissure had halted its advance but warned residents to stay alert and be prepared to abruptly evacuate.

“This eruption is still evolving and additional outbreaks of lava are possible”, the US Geological Survey said.

Air quality warnings were in effect for people around multiple fissures, with residents urged to limit their exposure to hazardous sulfur dioxide gas.

A series of earthquakes have rumbled through the region in recent weeks, helping to spur more volcanic activity. But officials in Hawaii, the island where Kilauea is erupting, said a morning tremor of a 4.2 magnitude was not enough to spur a tsunami warning.