Kilauea offered a bright display of light on Christmas morning as red-hot, liquid rock continued to stream out of the main fissure vent into the lava lake inside Halemaumau Crater.

But that vent began to drown between Christmas Eve and Christmas morning, and the illumination from the new eruption might not continue to glow as brightly.

In just over 24 hours, the main north vent along the crater wall was “buried” by 20 feet of lava as of 7:30 a.m. Friday, from 5 a.m. Thursday when it was about even with the lava lake’s surface, said U.S. Geological Survey Hawaiian Volcanoes Observatory geologist Frank Trusdell.

Once the vent is completely submerged by the rising lava lake, it will not be quite as bright, said the geologist, who was in the field for six hours on Friday.

As in the past, once the vent in a lava lake gets covered, the crust folds onto the surface, flounders and overturns, Trusdell said. Incandescent areas below the crust are still visible, but sometimes material spatters and gets thrown up into the area but it’s not quite as bright.

But the vent is not being submerged as quickly as it had been.

The rate at which Kilauea was pumping the liquid rock from two vents into the lava lake has slowed dramatically to 529 cubic feet per second on Thursday, down from 1,412 cubic feet per second on Wednesday.

The lake was 577 feet deep as of early Friday morning, rising 20 feet over the previous 24 hours, and the lake volume was at 4.8 billion gallons.

“Anybody who is a volcano watcher cannot take things for granted,” Trusdell said. “If you’re in the vicinity, you should go. … Maybe it’s going to end tomorrow.”

“This could last for a few days more or could be the start of the next 100-year event,” he said.

In the 1800s to early 1900s, the lava lake sustained activity for almost 100 years, Trusdell noted. At other times magma migrated, as in the 2018 eruption, and came out in the lower East Rift Zone.

“From most viewing areas that the park allows visitors to go, you can’t actually see the surface of the lava lake yet,” he said. “All you see are the illuminated walls of the crater — it gets lit up by the lava that’s flowing inside, and the eruption column.”

The reflection on the column of volcanic gas is what most people see.

Trusdell said the typical Hawaii eruption starts out from a fissure, a long crack from which the lava comes out of the ground.

But although the fissure is typically a long line, the entire line does not necessarily emit lava. Some parts emit gas, he pointed out.

In this eruption, three fissures initially opened up Sunday, and the middle one, which was lowest, is now totally buried.

The remaining two are being fed magma from the same crack underground, and the vertical feeder from the magma chamber, called a dike, is tall and narrow.

He could not say how large the vent diameter is. “We never got a real clear dimension of the width of the base of the fountain,” he said, since lava had already piled up and solidified by the time they arrived Sunday night.

USGS scientists are closely monitoring the tilt of the ground, earthquakes and other indicators around the flanks to determine what to expect the volcano to do next.

“We’re seeing the tilt is slowing down, which means possibly magma is slowing down,” he said. “When the magma chamber is filling up, the ground starts to bulge and the tiltmeter tilts. When it purges the lava, the tilt goes down.”

There is no indication another vent will open up on the wall of the crater, Trusdell said. Right now earthquakes are small and remain on the summit, so there is no indication that magma is moving away from the top.

“Every time a volcanologist speaks, it’s like the weatherman. Some of the inputs change and we update the forecast,” Trusdell said.

Trusdell, who was born and raised in Palolo Valley, started his career in geology in 1980.

“I never get tired at looking at lava. It’s always different, always something you can learn,” he said. “You shouldn’t wait and assume that the lava will be there tomorrow. We don’t have all the answers. There’s always something to learn and always surprises.”

Hawai‘i Volcanoes National Park spokeswoman Jessica Ferracane said that “the volume of lava is rising, and … I don’t think we will see any diminished glow until the lava recedes.”

“I’m pretty confident Pele’s glow after dark will remain bright and beautiful until conditions change,” she added. “Just because the vent is ‘drowned out’ by the lava lake doesn’t necessarily mean it has stopped pumping molten rock into the crater.”

Ferracane said Friday that there were thousands of visitors Christmas Eve, Christmas day was busy and Christmas night was expected to be busier.

Rangers were directing people to park at the overflow parking lots at places like Kilauea Overlook and Steam Vents. Both locations offer optimal viewing, but if those lots are full, you have to hike there.

Rangers suggest to come later at night if you want a closer parking spot, after 10 p.m. and before 5 a.m. Also, bring a flashlight if you plan to come after dark. If you are redirected, you could end up walking a mile on Crater Rim Trail in the dark.

Other great vantage points, which are less crowded, are Waldron Ledge and Volcano House. Park at Kilauea Visitor Center for those locations and it’s not a long walk. A flashlight is still needed after dark. You are farther away from the lava lake, but it’s still scenic and easy parking.

The KVC restrooms are open from 9 a.m. to 9 p.m., and rangers are staffing the KVC lanai during those same hours to answer visitors’ questions.

The tradewinds are picking up, Ferracane said, so air quality is good right now and is expected to be good for the next couple of days.