Mauna Loa’s first eruption in nearly 40 years continued to lose its punch Friday with further reductions in lava production, volcanic gases and fountaining.

“We’re seeing all the indicators that the eruption is slowing down,” Hawaiian Volcano Observatory Scientist-in-Charge Ken Hon said Friday afternoon during a Hawaii County Civil Defense Facebook Live appearance. “The real question here is, What happens next?”

Hon said the changes seen over the past two days have left two equally probable scenarios: One is that the flow could sustain itself at low rates for a few months or maybe over a year; the other is that the eruption is winding down and about to turn off.

The volcano is now producing “a 10th or 100th” of the output of lava it was generating just a few days ago, Hon said, and volcanic gases, which are a reflection of lava production, have gone from more than 100,000 tons a day a couple of days ago to 30,000 tons a day Thursday and even less Friday.

The 12-mile river of lava that had been threatening Daniel K. Inouye Highway, also known as Saddle Road, is now largely dead and cooling, having stalled 1.7 miles from the cross- island road.

Hon said Fissure 3 is no longer feeding the main flow and is instead producing slow-moving “sticky flows” that have stayed near the main flow channel within 1.25 miles from the vent, an area even more constricted than Thursday.

Fissure 3’s fountain, which only two days ago had shot lava hundreds of feet into the air, dwindled to 30 feet Friday morning and appeared to be even lower later in the day.

“So it’s a pretty rapid drop-off in the eruption,” the scientist said.

Asked how the changes would affect nighttime viewing of the lava, Hon said the views are probably not going to be great.

“The good news is that we’re not threatening anything any longer, so the road will be safe,” he said. “The bad news is the diminished output of the eruption is going to make it harder to see even at night because we just don’t have as much incandescent material going up in the air.”

The fountains are below the rim of the 95-foot-tall cone, he said, and the only thing visible at night will be a glow from the fumes. The lava flows are also much smaller, which means viewers will be able to see only spots of incandescence in the night.

“We’re pretty much done with that really high- effusion-rate, tall-fountain, spectacular part of the eruption,” Hon said.

After threatening to erupt for months, the world’s largest active volcano came to life late Nov. 27 for the first time since 1984, ending its longest quiet period in recorded history. The flows have traveled across the remote northeast rift zone and have remained far from populated areas.

The showy fountains and glowing rivers have mesmerized many, drawing more than 25,000 vehicles to a volcano-viewing area that was established over a week ago to increase safety on Daniel K. Inouye Highway.

Hawaii County Mayor Mitch Roth said he would consider closing the viewing area if the vista doesn’t keep drawing crowds. The county, he said, continues to pour substantial resources into the viewing area, including providing 24-hour security.

“It’s probably going to close, but we’ll see when and how much of a glow there is. If there is no glow, there’s really no reason for people to go on that road,” he said.

Hon said that while the eruption appears to be coming to an end, it’s very much possible that it could continue at a lower rate. Fissure 4 continues to produce lava at a rate of 1 to 4 cubic yards per second, which is the amount of magma scientists think normally feed into a typical Hawaii volcano.

According to the latest HVO update, tremor — an earthquakelike signal linked to subsurface fluid movement — continues beneath the active fissure. That indicates magma is still being supplied to the fissure, and the volcano is likely to continue producing lava as long as that signal is being recorded.

“We’re in an unstable part of the eruption right now,” Hon said. “It may be a few days or a week before we really know if this eruption is going to pause and then shut off, or if it’s going to slow down and keep going.”