Another fissure spewing lava and unhealthy gas opened up Monday on Hawaii's Big Island, and a crack in the Earth that emerged a day earlier was sending molten rock on a slow run for the ocean, officials said.

Nearly 20 of the fissures have opened since the Kilauea volcano started erupting 12 days ago, and officials warn it may soon blow its top with a massive steam eruption that would shoot boulders and ash miles into the sky.

A fissure that opened Sunday led authorities to order 10 people to flee their homes, Hawaii County Managing Director Wil Okabe said. Overall, nearly 2,000 people have been told to evacuate since May 3, and lava has destroyed more than two dozen homes.

The U.S. Geological Survey's Hawaiian Volcano Observatory said the flow from the crack that emerged Sunday was heading on a path that would take it to the ocean, about 2 miles (3 kilometers) away. No homes or roads were threatened by the flow.

Lava on Sunday spread across hundreds of yards (meters) of private land and loud explosions rocked the neighborhood not far from the Leilani Estates subdivision, where more than a dozen other active vents opened over the past week.

Nearby resident Richard Schott, 34, watched from a police checkpoint as the eruption churned just over a ridgeline 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."

Few fissures, ground deformation and abundant volcanic gases indicate eruptions on the eastern flank of Kilauea are likely to persist, the Hawaiian Volcano Observatory said.

"The appearance of the fissures in the past couple of days does not change the overall picture or concern," Geological Survey scientist Steve Brantley said.

Christian and Maritza Ricks, who moved to the area from California in April, stopped at 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," Christian Ricks said.

The Hawaiian Volcano Observatory reported a fissure opened Saturday 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.

As a precaution, plant workers last week removed 50,000 gallons (189,265 liters) of a flammable liquid stored at the site.