In early 1990 a tube-fed stream of red-hot pa­hoe­hoe lava slowly approached the coastal town of Kala­pana in much the same way a flow threatens the village of Pahoa today.

As it turned out, that relatively narrow flow of molten rock nearly 25 years ago was only the beginning of an escalating disaster that saw the entire community, including a church, store and more than 100 homes, buried under 60 feet of lava over a six-month period.

Question: Is Pahoa the next Kala­pana?

Answer: That’s up to Pele, the volcano goddess.

But geologists warn that similarities in the behavior of the two Kilauea flows suggest the Pahoa area is highly vulnerable.

Residents, they say, should not get their hopes up simply because the leading edge of the flow has not moved in the past week or so. There were lots of stops and starts during the Kala­pana flow, too.

In fact, in 1990 there were a dozen occasions when lava failed to even reach the vent feeding the flow for days at a time.

"Kalapana taught us the entire length of pa­hoe­hoe flows must be considered active, no matter how dead they appear," said Ken Hon, a University of Hawaii at Hilo geology professor who worked at the Hawaiian Volcano Observatory in 1990.

As for the current flow, the volcano continues to feed lava into the tube system, even though the front of the flow remains stalled 480 feet from Pahoa Village Road officials said. New breakouts of lava continue upslope, and the flow continues to thicken with new lava.

"It’s not over," said Frank Trusdell, a U.S. Geological Survey geologist who works at the Hawaiian Volcano Observatory. "The volcano is still supplying lava to the tubes, and people should remain vigilant. Now is the time for residents to continue their preparations in case something happens."

Hon and Trusdell, both veteran volcanologists, said the current flow, which started June 27, is strongly reminiscent of the initial river of lava that threatened Kala­pana.

The two flows share similar characteristics, they said, not the least of which is the way in which the lava would move in fits and starts.

Hon said the behavior of slow-moving flows of pa­hoe­hoe lava are notoriously difficult to predict. For instance, on flat ground they can appear inactive for hours — or even longer — as they inflate and thicken with a hardened crust.

Interruptions in the amount of lava reaching the front of a flow can be caused by changes in both the volcano’s output of lava supply or by blockages in the lava tube system.

Both, Hon said, can make the flow temporarily stop, creating false hopes that the crisis has ended.

Hon said pauses caused by temporary drops in the amount of lava feeding the flow have been common in Kilauea’s eruptive history over the last quarter-century. Flows can slow down, stop and restart during intervals from weeks to months at a time.

While this might seem like a good thing at the time, he said, lava can break out along any point in the lava tube system, threatening anew as lava production continues.

Trusdell said it’s possible that over weeks to months the June 27 flow could branch out, allowing it to cover larger swaths of ground. And over months or years, the flow could overwhelm almost anything in its way.

At Kalapana over two months in 1990, multiple pauses resulted in new flows that spread out over different paths, covering an ever wider area and eventually engulfing the town, Hon said.

While most of the damage occurred in 1990, lava first made its way into the Kala­pana area in 1986, covering roads and torching 17 homes.

Less than four years later, blockages formed in the lava tubes that were carrying lava to the sea west of Kala­pana started diverting the flow toward the coastal community. Pauses in the flow also helped to create new rivers of lava flowing in that direction.

Eventually, lava oozed past the outskirts of Kala­pana and right through the heart of town. From April 1990 to February 1991, lava burned homes and gardens and relentlessly buried the entire community under some 60 feet of lava.

Walter’s Kalapana Store and Drive Inn was burned and covered by lava in early June, and the famous Kaimu black-sand beach and its park were paved over with lava. The Kaimu surf break was also ruined as a new shoreline was created nearly 1,000 feet farther into the sea.

Hon was conducting hazard assessment for Hawaiian Volcano Observatory at the time, providing information on lava movement to Hawaii County Civil Defense, which made decisions regarding evacuation, road closures and safe vantage points for residents and visitors.

"It was a difficult job," he remembered. "It was unrelenting, 24 hours a day, and it went on for months and months. It was a lot of hot, physical work. It was not easy to watch families let go of their community as it was slowly inundated by lava.

"I felt really bad for the people there," he said.

As for the current eruption: "Lava is in the town," he said. "This is not a good sign."

Hon said pa­hoe­hoe lava flows are often initially narrow and relatively thin, and when they pass through a neighborhood, they might damage only a few properties. But it is common for such flows to eventually spread and thicken to 10 to 20 feet deep, he said.

Pressure within a flow can fracture the crust at the margins at any time, he said, creating a new flow lobe and making new targets of properties that may have been spared by the original passage of the flow front.

While there are plenty of similarities between Kala­pana and the current flow, there are some differences as well.

At 13.5 miles in length, the June 27 flow is already the longest flow since Kilauea started erupting again in 1983.

"It’s very strange," Hon said. "We haven’t seen a flow this narrow go this far."

A 3-mile system of cracks has helped to channelize the flow and move it farther within a narrow path, Trusdell noted.

Another significant difference is the amount of lava flowing through the tube system. In 1990 roughly 350,000 cubic meters per day of lava was flowing, he said, while this eruption so far is generating only about 100,000 cubic meters per day.

What implication that has for the future of the June 27 flow and the people in harm’s way is uncertain, Trusdell said.

Kilauea, considered one of the world’s most active volcanoes, has been continuously erupting now for almost 32 years. How long could this go on?

That’s another one for Madam Pele.

But keep in mind, Trusdell said, that Kilauea’s longest known eruption, called Aila‘au, lasted more than 50 years, spreading lava through a lengthy network of lava tubes in the 15th century and covering a vast area of Puna now occupied by neighborhoods such as Hawaiian Acres, Aina­loa, Hawaiian Paradise Park and Hawaiian Beaches.

Correction: The front of the Kilauea lava flow on Sunday was 480 feet from Pahoa Village Road, not Highway 130 as was reported in an earlier version of this story.