A MASSIVE new fissure opened on Hawaii’s Kilauea volcano, hurling bursts of rock and magma with an ear-piercing screech as it threatened nearby homes and prompted authorities to order new evacuations.

The fissure, a vivid gouge of magma with smoke pouring out both ends, was the 17th to open on the volcano since it began erupting on May 3.

Seen from a helicopter, the crack appeared to be about 300 metres long and among the largest of those fracturing the side of Kilauea, a 1200-metre high volcano with a lake of lava at its summit.

Hawaii County Civil Defense issued an emergency cellphone alert after the fissure was discovered.

The agency said one “unidentified structure” was destroyed by the new vent, bringing the total number of homes and other buildings lost to the lava to nearly 40.

Residents in the immediate area were told to evacuate, and two nearby community centres were serving as shelters for people and pets.

Lava spread across hundreds of yards of private land and loud explosions rocked the neighbourhood not far from Leilani Estates subdivision, where more than a dozen other active vents have opened in the past week.

Nearby resident Richard Schott, 34, sat near a police checkpoint and watched as the eruption churned just over a ridge line and behind some trees.

“I’ve actually seen rocks fly over the tree line and I can feel it in my body,” Schott said.

“It’s like a nuclear reaction or something.”

The new opening was still showing signs of activity.

“It is a near-constant roar akin to a full-throttle 747 interspersed with deafening, earth-shattering explosions that hurtle 45kg lava bombs 30 metres into the air,” said Mark Clawson, 64, who lives uphill from the latest fissure and so far is defying an evacuation order.

Closer to the summit, in the evacuated Leilani Estates neighbourhood of about 1500 people, explosions could be heard in the distance as steam rose from cracks in the roads. The bulging rim of one fissure wrecked a building, leaving behind torn metal.

In areas where sulfur dioxide emissions were strong, the vegetation turned brown and leafless trees withered.

Meanwhile, other fissures continued to billow smoke over homes on the eastern point of the Big Island of Hawaii, the largest of the Hawaiian Islands. Even so, some people such as Clawson remained in their homes, confident they would be spared.

“We are keeping track of lava bombs. One went through the porch roof of a neighbour’s house,” Clawson said. About eight to 10 neighbours had yet to evacuate, he said.

The Hawaii National Guard warned people in the coastal Lower Puna area to prepare to leave, saying anyone who chooses to stay behind cannot count on being rescued. An evacuation has not been ordered there but might be if a local highway is cut off.

“We’ve been telling them, ‘Evacuate if you can, because if we have to come in and get you we’ll be putting first responders at risk’,” Major Jeff Hickman told reporters. “There’s a point where we’ll tell our first responders, ‘Nope, you can’t go’.”

The U.S. Geological Survey’s Hawaiian Volcano Observatory said new fissures, ground deformation and abundant volcanic gases indicate eruptions on the eastern flank of Kilauea are likely to continue.

“The appearance of the fissures in the past couple of days does not change the overall picture or concern,” USGS scientist Steve Brantley said.

Christian and Maritza Ricks, who moved to the area from California in April, stopped on the side of the road to watch and listen to the latest eruption.

“I guess it’s just part of living on the island,” Ricks said.

He said he wasn’t really afraid of the destruction happening around him.

“In a way it’s kind of exciting to see what’s going on and be this close to it.”

Most of the lava outbreaks have occurred in and around the Leilani Estates neighbourhood, where molten rock has burst through the ground, destroying more than two dozen homes and resulting in evacuation orders for nearly 2,000 people.

The U.S. Geological Survey has reported nearly 20 active fissures.

One that opened Saturday night was spattering, but no flow had formed.

The Hawaiian Volcano Observatory reported the fissures opened just east of the Puna Geothermal Venture energy conversion plant, where steam and hot liquid are brought up through underground wells and the steam feeds a turbine generator to produce electricity.

Plant workers last week as a precaution removed 189,265 litres of a flammable gas stored at the site. Geologists warn that Kilauea’s summit could have an explosive steam eruption that would hurl huge rocks and ash miles into the sky.