Mauna Loa eruption Day 10: Leading front of lava flow about 1.8 miles from Saddle Road; overflow breaks out upslope

This story was updated at 4:01 p.m. Dec. 7

A Tuesday evening update from Hawai‘i County Civil Defense saying the front of the lava flow being pumped out of fissure 3 on Mauna Loa’s Northeast Rift Zone was approaching 1.5 miles away from Daniel K. Inouye Highway, or Saddle Road, was an error, according to officials with the U.S. Geological Survey.

The front is still about 1.8 miles from the highway as of this morning and continues to move very slow and spread out in all directions, according to Hawaiian Volcano Observatory Deputy Scientist-in-Charge David Phillips. So it’s just more than 0.1 miles closer to Saddle Road than Tuesday morning.

Phillips said during a press conference Wednesday morning that there is no clear leading edge of the front and it’s not really favoring moving east or west at this time. Otherwise, there’s been no significant change in the eruption since Tuesday.

“The flows follow the lay of the land,” he said.

Fissure 3 remains the only active fissure and is generating a lava flow traveling north toward the highway. There was an overflow of the lava channel about 2.5 miles upslope from the flow front and the observatory is watching that development to determine if it has any potential impacts. The breakout, however, is expected to slightly slow the advancement of the main flow front.

“We’re watching to see what it does, where it goes and if it remains active,” Phillips said.

The question of when and if the lava flow reaches and crosses Saddle Road is on everyone’s minds.

“That’s a question we’re all asking, for sure, and I wish we could give a better answer,” Phillips said, adding the basic message hasn’t changed. The flow front is on very flat ground and moving slowly and based on the flow’s current behavior and all the variables involved, it’s difficult to forecast if, when and where it could intersect with the highway.

The situation is constantly changing and there is a range of various models.

Hawai‘i County Mayor Mitch Roth said discussions are underway for plans if and when the lava reaches the highway, but reiterated that there are a lot of variables to take into account.

The decision to close Saddle Road would be made based on where the flow front is located and how much time it will take to get to the highway as well as safety concerns, including how long it will take to remove all County and state equipment from the area, air quality, burning vegetation possibly releasing methane that could result in a dangerous situation and even human behavior when it comes to following the rules for viewing the flow.

There’s not one simple development that would lead to the closure of the main thoroughfare between the east and west sides of the island.

“There are a lot of variables,” Roth said. “It’s still a very fluid situation.”

The mayor did say that discussions have included talks about where the road could be closed if the lava crosses, possibly near the 8- or 10-mile markers on the highway on the Hilo side and somewhere near the bottom of Saddle Road on the Kona side, but no definitive decisions have been made yet.

The Royal Order of Kamehameha this week will be going up to the Mauna Loa access area to prepare for the the lava flow’s arrival. Roth said the County is assisting the group’s efforts and motorists on Saddle Road could see people in that area Friday making preparations and performing cultural practices.

There is no active lava within Moku‘āweoweo caldera nor the Southwest Rift Zone. No eruptive activity is expected outside the Northeast Rift Zone. No communities are at risk and Daniel K. Inouye Highway remains open in both directions.

Roth also reported that about 17,000 vehicles have gone through the County’s new 4.5-mile lava viewing route on Old Saddle Road through Pōhakuloa Training Area land since it was opened last week. Tuesday wasn’t such a great day for viewing because of reduced visibility from the inclement weather, but the mayor said trade winds have returned and there are better air conditions today, so viewing should be better.

Unfortunately, people continue to disregard the rules, wandering off the route and into prohibited areas. The area off Saddle Road where the lava flow is located is completely off limits. The area encompasses Hawai’i Department of Land and Natural Resources, Pōhakuloa Training Area and Department of Hawaiian Home Lands lands, all of which have prohibited access. The County definitely doesn’t want people going into those areas because of safety reasons.

There also have been reports of people throwing marshmallows or trash into the lava flow. Roth said actions like those are not only bad for the environment, they are disrespectful to the Hawaiian culture. He reiterated that people should stay by their cars, not wander into closed areas, be careful and be pono.

Denise Laitinen, public relations specialist with the Hawai’i Police Department, reported during Wednesday’s press conference that police issued three citations Wednesday night, all for parking, and there were no traffic collisions connected with people viewing the lava. Police are enforcing parking rules in the area.

Roth said the County is working with the governor’s office as far as what the punishment will be for people found wandering off the viewing route and into prohibited areas. He expects an announcement soon.

Sulfur dioxide emission rates of approximately 120,000 tonnes per day (t/d) were measured Dec. 4 and remain elevated Tuesday. The International Volcanic Health Hazard Network has detailed information about vog. Forecasts for the dispersion of vog can be found on the Mauna Loa Vog Forecasting Dashboard.

Pele’s hair, strands of volcanic glass, fragments are being wafted great distances and have been reported as far as Laupāhoehoe.

Phillips said Wednesday, however, he doesn’t think the density of Pele’s hair is high outside the area of fissure 3 and in the saddle region. That’s not surprising and expected given how large and tall Mauna Loa is, sending a plume of volcanic emissions into the air until it hits wind shear. Then, depending on which way the wind is blowing, Pele’s hair and other emissions might be found anywhere on island.

Tremor, a signal associated with subsurface fluid movement, continues beneath fissure 3, indicating magma is still being supplied. Activity is likely to continue as long as the Hawaiian Volcano Observatory sees this signal.

Phillips said at this point, Mauna Loa is in a phase where it is only erupting ‘a‘ā lava, consistent with past eruptions that lasted about two to three weeks, but every eruption is different and unique and at this point, there’s no signs of diminishing activity.

To watch the fissure 3 eruption via livestream, click here. Intermittent interruptions are expected today as the U.S. Geological Survey is having camera connection and website hosting issues. Hawaiian Volcano Observatory crews also installed a new webcam to view the front of the main flow. To view that webcam, click here.