PAHOA, Hawaii » The unpredictable lava that’s invading Pahoa came within 100 feet of a two-story home Wednesday and then suddenly stalled, underscoring the difficulty of predicting what the flow will do next.

Asked Wednesday when the flow will end, Frank Trusdell, a geologist with the Hawaiian Volcano Observatory, offered little hope of a quick ending.

"This eruption’s been going on for 30 years" — and it’s not uncommon for flows to last 50 to 60 years, Trusdell said at a press conference.

Then Trusdell offered even more disheartening perspective.

"On Mauna Loa," he said, the geological record shows that "there was a period where lava flows lasted five centuries."

Hawaii County officials every day have been praising the patience of worried residents while acknowledging their frustration at not knowing what the molten rock will do next — or when.

On Monday, the two-story rental home appeared to be the first building that would be overrun by lava. But by Tuesday morning, the slow-moving lava had turned and instead took out a 10-foot-by-15-foot utility potting shed on the adjacent property.

Then the house appeared headed for destruction again Wednesday morning when a finger from the flow came just 100 feet away. Hours later, the finger simply stopped moving.

But the leading edge of the flow continued toward Pahoa Valley Road — Pahoa’s main street — at a rate of 10 yards per hour and was 270 yards away from overrunning it Wednesday.

U.S. Rep. Tulsi Gabbard, who represents the neighbor islands, flew the entire 13-mile length of the flow Wednesday in a county fire department helicopter along with Mayor Billy Kenoi and called the sight "pretty ominous."

While attention remains focused on the leading edge and intermittent fingers and "breakouts," Gabbard said she was concerned with the volume of lava coming up from behind.

"I know it’s slowed down somewhat, but then you see the entire 13 miles marked by smoke and steam that’s rising," she said. "And the relatively small fingers that are poking through are a little bit deceiving when you look at the width of the flow coming right behind it."

Gabbard, a captain and military police officer in the Hawaii National Guard, could deploy Thursday with 80 unarmed airmen and soldiers who will be under the command of Hawaii County police as a "presence patrol" to, in part, keep outsiders out of a cordoned-off neighborhood of 15 to 20 homes nearest the flow on Apaa Street.

"I know everyone is curious and wants to get close to the flow," said Hawaii County Civil Defense Administrator Darryl Oliveira. "But we need to respect people’s privacy."

Behind the blockade Wednesday, Kenoi and Gabbard spent an hour walking the neighborhood around Apaa Street and meeting with 40 to 50 residents who were in "positive spirits" even while packing and preparing to give up their homes to lava, Gabbard said.

The attitude of the residents, Gabbard said, provides "great motivation for all the people working so hard."

And her message back to the residents was that county, state and federal officials will be there to help recover from whatever fate the lava will deliver.

But as the flow continues to stop, stall and move in different directions, Gabbard said it’s far too soon to know how much damage it will leave behind.

So the question, Gabbard said, is "how this will impact our community, our children, our kupuna for some time to come."