Mauna Loa lava still spewing, but flow only creeping toward main Big Island road

The lava from the Mauna Loa eruption continues to spew out of Fissure 3 — and at a larger volume than previously estimated — but the main flow continues to move slowly and behave like “really, really thick pancake batter.”

In the past day the lava flow has progressed less than a tenth of a mile and is now about 2.2 miles from reaching Daniel K. Inouye Highway, according to figures from the Hawaiian Volcano Observatory.

“The lava flow is advancing sideways to the west and east about as fast as it is moving forward,” said Ken Hon, the federal observatory’s Scientist-in-Charge.

The front of the lava flow is about 15 feet thick and moving at about 50 feet per hour. At this rate, the lava would take at least another week to reach the Big Island’s main east-west highway, also known as Saddle Road.

At its current path, the lava flow is headed near the intersection of Old Saddle Road and Daniel K. Inouye Highway,

Scientists continue to say there are still too many variables to determine when the lava will cross the road — or even if it will.

“We still don’t know,” Hon said.

In the meantime, Hawai’i County and other government agencies continue to plan for the possibility of a road closure.

The county also is continuing to work on making the traffic flow along the highway — which is used daily by thousands of residents for work, business and other everyday reasons — as efficient as possible.

The influx or people who have flocked to the area to see the lava flow down the northeast flank of Mauna Loa has remained steady since Mauna Loa erupted a week ago, at about 11:30 p.m. on Nov. 27.

On Sunday morning, the 4.5-mile section of Old Saddle Road on Pōhakuloa Training Area land that had been created days earlier as a lava viewing area had to be shut down for hours following the discovery of unexploded ordnance.

Lt. Col. Kevin Cronin with the U.S. Army Garrison said the item found Sunday was “a training ordnance that produces smoke, so not a bomb that would produce any type of shrapnel or fragments.

“Based on the current flow and based on the conditions of the training areas on Pōhakuloa, weʻre not concerned about UXO [unexploded ordnance]or any other type of toxin to the team working at Pōhakuloa, the 200 civilian teammates, the public community or the broader Hawaiian island community.”

But there likely is more unexploded ordnance in the area because it is an active training area, Lt. Cronin said.

The civilian who found the ordnance, which was in lava off of the road, was trespassing. The public is only allowed to be on the roadway and parking area along the viewing route while on military grounds.

The Mauna Loa Forest Reserve also has been closed to the public since shortly after the volcanic eruption began one week ago. Yet, even after the discovery of unexploded ordnance on Sunday, many people continued to trespass into the closed area.

On Sunday, officers from the state Division of Conservation and Resources Enforcement warned a dozen people to stay out of the active lava zone.

During a media tour, Hawai’i Island Branch Chief Lawrence Terlep Jr. spotted a trio of people walking down Mauna Loa Access Road, which is closed. They told Terlep they thought “the road was only closed to cars.”  

People caught in closed areas risk getting seriously hurt walking across uneven ground in the dark, and recent lava flows could still be extremely hot. Violators can be cited or arrested.

Drew Downs, a geologist with the U.S. Geological Survey, described the molten rock as being fluid like water when it comes out of the mountain, but as it is cooled by the air and travels down the slopes it becomes thick like syrup or molasses.

To date, the lava has covered an area of about 13.5 square miles and traveled about 4.1 miles from the vent.

Federal field teams have determined that the rate of lava spewing out of the mountain is larger than previously estimated, now at about 100 to 150 cubic yards per second, which is is roughly the same amount that was produced by the Kīlauea eruption in 2018 on the Big Island.

“There is no slowing of the material coming down the channels and feeding that [lava flow] front,” Hon said. “The front just moves very slowly because the material is very viscous [thick and sticky] and the ground is very flat.”

There has been some branching of the lava channels overnight. The westernmost channel had a breakout to the west.

“This is some of the uncertainty that we have,” Hon said. “We have two big main feeder channels that come down and merge to make the front. But either one of those channels could fail and send another lava flow off in one direction or another. An eastern channel that could send lava to the east and a western channel that could send lava to the west.”

It was a small breakout to the west and Hon said it could already be stagnant and not likely to divert the direction of the main flow, but he said it is an example that branching is possible.

The scientists have been monitoring the type of lava that is coming out of the vent.

“It is very bubble-rich,” Hon said. “It is basically like a foam, almost like whipping cream or shaving cream right now. And then it collapses as the water bubbles leave as it travels down the channels.”

On Monday, there is little wind at the 10,500 foot elevation of the mountain where the event is spewing lava. Most of the toxic gasses is “going up quite high” and not endangering people on the Big Island, Hon said.