Alaska News

Post-earthquake blast shot roof 40-50 feet into air, investigation found

A fire department investigation into the explosions and fires that rocked a Kenai neighborhood following January's big earthquake found no human error, but the review unveiled dramatic new details about the events after an underground natural gas line ruptured during the 7.1-magnitude temblor.

Among the new information: When the gas blew up in the hours after the earthquake, two workers narrowly escaped injury because they were behind a big tree as debris rocketed in their direction. Officials are also concerned that gas may still be trapped in underground pockets in the neighborhood, posing a continuing hazard.

Tommy Carver, fire marshal with the Kenai Fire Department, said the department wrapped up its investigation on Monday. He would not release the report because it is not yet in its final form, but he agreed to share details of the investigation.

Enstar Natural Gas is still conducting an internal investigation into the events, said John Sims, vice president of business development and corporate resources. Sims said he did not know when that investigation would be complete. He would not comment on details provided by the fire department.

The earthquake occurred at about 1:30 a.m. on Jan. 24 and was widely felt across Southcentral Alaska.

The department believes the explosions in the area off Lilac Lane in Kenai were caused when the earthquake ripped open a 1 1/4-inch line leading to smaller individual house lines, Carver said. The department believes the break in the larger line led to two early morning explosions spaced a few hours apart.

One blast shot a roof about 40 to 50 feet into the air.

The fire that followed the second explosion burned four homes and three vehicles. There were no reported injuries, he said.

"I think the gas leak was caused by the earthquake, and then gas migrated up through the foundations because that was the path of least resistance," Carver said. The gas could not escape through the frozen soil, he said.

The gas then found an unknown ignition source, though the power had gone out with the earthquake, he said.

"It could have been anything from a static-electricity source to a pilot light that may have still been on if they had an older appliance," Carver said. "It could have been a candle in someone's house."

The fire department responded at 2:13 a.m. to the first explosion that caused a small fire in a crawl space, Carver said. The explosion moved the house slightly off its foundation. Bolts that should have been sticking straight up out of the concrete foundation were not, Carver found.

"They were flat, facing outwards, and a wall was displaced about four inches," he said.

The fire department put out that fire quickly and shut off the gas meter to the house. With fire personnel still detecting a strong gas odor, they worked with the police department to evacuate the neighborhood. A handful of Enstar workers remained in the area, looking for the leak. The fire department cut off access to the area, but remained close by on standby.

The second blast occurred at 5:54 a.m. in a house next door to the original explosion, Carver said.

"With no advance warning whatsoever the house next door blew up," he said.

"That was a much larger explosion, destroying the entire house," Carver said. "The garage door was blown across the street, as was a large living room bay window. The roof of the house was blown about 40 to 50 feet in the air."

Two-by-fours and other debris have been found up to 200 yards away from the house, he said. That fire engulfed three other houses, including the house where the original blast occurred. The threat of more gas explosions prevented firefighters from battling the blazes.

"We're not used to that sort of thing," Carver said. "When something is burning you want to get in there and put it out."

At the time of the second explosion, Carver said two Enstar employees were within 30 feet of the house, digging a trench with a small excavator to find the source of the leak. He said they were working behind a large spruce tree that may have prevented their injury, perhaps even saved their lives.

"The garage door and bay window flew right by the Enstar employees," Carver said.

Two firemen who had been standing by after Lilac Lane had been blocked off had recently returned to check on the workers and to move a hose that appeared to be in the way of the excavator.

One of them was Tony Prior, the fire department's battalion chief, who said he never noticed the garage door or window blowing across the street.

"It was loud for a split second, then the pressure wave hit you, and then it's more of a dull feeling," he said.

"When major events like that occur your mind gives you still frames of what happened, and I saw the whole roof frame flying off the house," Prior said. "I couldn't tell you how high. I just know it lifted up toward the treetops and it kind of blew backwards, behind the houses.

"I don't know where it landed because I immediately looked down to see if the Enstar guys were OK. They were and then I said everyone get out of here."

Carver on Tuesday said Enstar personnel are continuing to probe for pockets of gas that may be trapped beneath the frozen ground.

Sims, with Enstar, said the company is "continuing to ensure the safety of residents. But at this point, we don't think there's anything to be concerned about."

Alex DeMarban

Alex DeMarban is a longtime Alaska journalist who covers business, the oil and gas industries and general assignments. Reach him at 907-257-4317 or alex@adn.com.

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