Story highlights Front of lava flow doesn't budge, "but there's lots of activity behind it," official says

He says residents ready to evacuate are "very upset, distraught, frustrated"

A geologist says "the flow is still active;" things could change at any moment

The lava flow on Hawaii's Big Island began in June; houses and roads are threatened

The lava flow has slowed, if not stalled altogether.

Still, authorities warned Thursday that the threat to eastern Hawaii residents -- much like the oozing, simmering, destructive lava itself -- hasn't gone away.

Darryl Oliveira, the director of the Hawaii County Civil Defense, told reporters that "there's been no movement forward" at the front of the destructive lava stream between Wednesday and Thursday.

"But there's lots of activity behind it," Oliveira said. "... There are breakouts along the margins that we'll have to watch and be wary of."

The lava began moving toward the area of Pahoa, on Hawaii's Big Island, in June, when a volcanic crater vented and released the river of liquid rock.

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Photos: Lava crawls from Kilauea Photos: Lava crawls from Kilauea Lava crawls from Kilauea – Lava flows near a residential structure in Pahoa, Hawaii, on Monday, November 10. The lava flow from the Kilauea Volcano is advancing on the community of about 950 people on Hawaii's Big Island and claimed its first home in the town, which has been watching the slow-moving flow approach for months. Hide Caption 1 of 12 Photos: Lava crawls from Kilauea Lava crawls from Kilauea – Lava burns near the town of Pahoa on Sunday, November 9. Hide Caption 2 of 12 Photos: Lava crawls from Kilauea Lava crawls from Kilauea – Lava flows over a fence marking a property line near the town of Pahoa on Friday, October 31. Hide Caption 3 of 12 Photos: Lava crawls from Kilauea Lava crawls from Kilauea – Lava burns vegetation as it approaches a property boundary early on the morning of Tuesday, October 28. Hide Caption 4 of 12 Photos: Lava crawls from Kilauea Lava crawls from Kilauea – Pictured here on Tuesday morning, October 28, lava had crossed into two privately owned properties. Hide Caption 5 of 12 Photos: Lava crawls from Kilauea Lava crawls from Kilauea – Smoke rises near Apa'a Street and Pahoa Village Road in Pahoa, Hawaii, on Monday, October 27. Hide Caption 6 of 12 Photos: Lava crawls from Kilauea Lava crawls from Kilauea – The horizontal incandescent cracks seen in the center and right portions of the photo, taken October 25, indicate that the flow was inflating: Fed by a continuing supply of lava beneath the cooling crust, the surface slowly rises. Hide Caption 7 of 12 Photos: Lava crawls from Kilauea Lava crawls from Kilauea – Hawaiian Volcano Observatory geologists walk over the surface of the flow to track surface breakouts along a portion of the flow margin, about a kilometer (0.6 miles) up the slope from the flow front, on October 24. Hide Caption 8 of 12 Photos: Lava crawls from Kilauea Lava crawls from Kilauea – Another view of the leading tip of the flow as it moves into the open pasture on October 24. Hide Caption 9 of 12 Photos: Lava crawls from Kilauea Lava crawls from Kilauea – Pu'u O'o Crater, in the eastern rift zone of Kilauea, remains filled with thick fumes, but recent views with the naked eye and thermal camera confirm that little change has occurred in the crater over recent weeks. The fumes mask a handful of small, glowing openings on the crater floor. Hide Caption 10 of 12 Photos: Lava crawls from Kilauea Lava crawls from Kilauea – A closer view of surface activity on September 15. "A lot of smoke (is) coming off the front, a lot of cracking noises, methane explosions are going on," said Tim Orr of the U.S. Geological Survey (USGS). "So, it's a noisy situation out there just from all the burning vegetation." Hide Caption 11 of 12 Photos: Lava crawls from Kilauea Lava crawls from Kilauea – A view of the sinuous, channelized flow that was moving to the northeast from Kilauea on June 27. The flow threatening Pahoa has advanced about 13 miles (21 kilometers) since then. Kilauea is one of the world's most active volcanoes. Hide Caption 12 of 12

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It's been creeping along ever since, with authorities warning at one point the main road in Pahoa could be overcome by Friday morning.

The lack of recent movement changes that equation, though the main flow -- which is about 20 yards wide at its tip, expanding to 100 yards farther back -- is still within about 480 feet of that street.

There's no guarantee of what happens next, including whether the stream resumes its forward movement or whether any of its offshoots encroach on people or properties. A USGS geologist has said the lava flow could continue for 30 years.

As Matthew Patrick, a geologist with the Hawaii Volcano Observatory, explained Thursday: "The flow is still active, and there is still scattered activity in the flow.

"So it's just a matter of where that activity is at any given moment."

On Wednesday, Oliveria said about 20 families in the path of the lava have been told to evacuate. Many others have packed up, "prepared to move at a moment's notice" should they, too, get the order.

"You can see some of them walking around; they are still very upset, distraught, frustrated -- the full range of emotions as they're dealing with this crisis," the civil defense director said Thursday.

So far, thankfully, no homes have been buried. Nor have any vehicles. Instead, it's mostly grass and vegetation that have been immersed and scorched.

This isn't a lazy river, after all. It's a 2,000-degree river of molten rock, the kind that a firefighter can't use a hose to stop.

"As it moves across soil, you can hear and smell the fire," said Troy Scott of the Hawaii County Civil Defense Agency. "It is incredibly hot ... the heat is very strong."

That's why there are ongoing efforts to make sure people and property are protected, as well as to clear out any hazardous materials, such as those at a one-time gas station, in the lava's potential path.

Local civil defense officials got some help Thursday, in the form of 80 Hawaii National Guard members. Oliveria explained that these guardsmen will drive around on patrols as an extra set of eyes.

He said, "As long as we need them, they'll be here."