PAHOA, Hawaii >> The Kilauea summit stole the show Tuesday as volcanic activity within Halemaumau Crater launched an ash cloud that sent debris 12,000 feet into the air and prompted warnings for aircraft in the area.

Meanwhile, 25 miles away at the Lower East Rift Zone, the ongoing eruption continued with a new fissure opening near the Lanipuna Gardens subdivision, and Hawaii County Civil Defense officials continued to warn of dangerously high levels of volcanic fumes and gases.

The new fissure produced little lava, and the longer flow from fissure No. 17, which has advanced more than a mile in recent days, slowed considerably Tuesday, according to county Civil Defense officials.

“Field reports are that the flow moved about 1,200 feet in the past day, but it is not moving very much at the moment,” said Steven Brantley, deputy scientist-in-charge at the U.S. Geological Survey’s Hawaiian Volcano Observatory, during a briefing for reporters.

EVACUATION ROUTES

The state Department of Transportation reopened Highway 130 in Lower Puna at about 2 p.m. Tuesday after dropping metal plates to cover cracks that had opened in the pavement more than a week ago.

That highway to Kalapana is now open to local residents only but will provide relief from long detours along a coastal highway to get in and out of Kalapana and the surrounding communities. State officials said heavy equipment and trailers should not be used on the highway.

Hawaii County Managing Director Wil Okabe said county officials plan to begin paving about four miles of Highway 137, or “Beach Road,” today to provide a better coastal evacuation route for residents in the Kalapana, Pohoiki, Kapoho and Opihikao areas.

ROCKFALLS AND EXPLOSIONS

The focus of activity Tuesday were the rockfalls and gas explosions that put on an impressive show at Halemaumau Crater, sending a gray plume several thousand feet into the sky and sprinkling ash as much as 20 miles to the southwest, scientists said.

Michelle Coombs, a USGS research geologist, said scientists aren’t certain what exactly triggered the plume of dark ash.

The USGS had warned of possible violent explosions if the magma at the summit drained below the water table, flowed into a hot magma conduit, plugging the conduit and building up steam pressure that could trigger blasts of rock and debris.

However, the magma conduit Tuesday was apparently clear, Coombs said. The ash plume that was pushed out of the summit Tuesday could have been driven by steam from evaporating groundwater or from rockfalls into the magma, or a combination of the two, she said.

“Because this is kind of new activity and we’re at a phase that is a bit unfamiliar to us, we’re not sure of the exact mechanism of these slightly more intense ash emissions today,” Coombs said.

AIR QUALITY CONCERNS

The tradewinds from the northeast pushed much of the ash to the southwest and into Kau on Tuesday, but the National Weather Service warns that the wind will weaken today, allowing the volcanic gas and ash hazards to be more concentrated over more of Hawaii island. The wind is then expected to pick up again by Thursday and should strengthen on Friday.

David Damby, a chemist and volcanologist with the USGS, said the ash from the summit is essentially “rock powder” and is not poisonous.

“You just want to limit your exposure to it,” he said, because it can cause eye, nose and throat irritation. “If you don’t need to be out in it, don’t be out in it.”

The air quality in Pahala on Tuesday morning was classified as “unhealthy,” according to the University of Hawaii’s Vog Measurement and Prediction Project.

Damby said state and county officials are working on a plan to make face masks available to the general public that can protect against ash particles for people who do need to be outside, but warned that those masks will not provide any protection against volcanic gases.

POWER OUTAGES POSSIBLE

The Hawaiian Volcano Observatory also issued a “notice for aviation” Tuesday warning pilots that the ash plume was reported as high as 12,000 feet, and conditions could become “more explosive.” HVO upgraded its aviation condition alert to red from orange.

Hawaii Electric Light Co. warned that volcanic ash falling on parts of Hawaii island also could lead to extended power interruptions.

A combination of a dusting of ash and moisture on utility insulators could cause electrical short circuits, and extended power interruptions are possible if the ash fallout covers a large area or is so heavy that it damages utility equipment, according to a HELCO spokeswoman.

Ormat Technologies Inc., which owns the shuttered Puna Geothermal Venture plant on the East Rift Zone, issued a statement Tuesday that the steepest topographical paths that lava might follow “are around and away from the power plant in the direction of the ocean.”

“This gives the company confidence that there is a low risk of surface lava impacting or making its way to the facility,” the statement said.

Isaac Angel, CEO of Ormat Technologies, said there has been no damage to the above-ground portions of the 38-megawatt plant, and “we expect to restore the Puna operations as soon as it is safe to do so.”

Tom Travis, administrator of the Hawaii Emergency Management Agency, announced Monday the state and county are moving forward with a plan to kill three active geothermal wells on the PGV site by injecting them with cold water and sealing them with iron plugs.

For more information on the hazards of volcanic ash and vog, go to volcanoes.usgs.gov and vog.ivhhn.org.