Advance of lava from Mauna Loa eruption slows, but threat to key Hawaii Island highway remains

Scientists say they are uncertain about the lava's next path, but the lava's slow advancement gives time for preparation.
Published: Nov. 30, 2022 at 9:33 AM HST|Updated: Dec. 2, 2022 at 8:23 AM HST

HILO (HawaiiNewsNow) - Lava from Mauna Loa slowed its advance toward the Daniel K. Inouye Highway on Thursday as it reached flatter ground, but officials were still bracing for lava to cross the key thoroughfare.

They say it could take about a week for lava to reach the highway ― now about 2.7 miles away.

The highway, also known as Saddle Road, connects Hilo and Kona and there is significant concern about what its closure would mean for commuters and the transport of goods and services. The alternate route is much longer.

Ken Hon, scientist-in-charge at Hawaiian Volcano Observatory, said Thursday night that the flow had slowed to about 30 yards per hour.

“It’s right at the divide where it possibly could go to the Hilo side or the Kona side,” said Hon. “Not that it will reach either one of those places, but we don’t know if it’s going to go east or west in the saddle.”

“It has hit the flats and it has really slowed down quite considerably,” Hawaii County Mayor Mitch Roth told HNN.

New viewing area set up for lava spectators amid concerns over congestion, safety

“The earliest it could reach the highway is about a week from now, going at the rates it was going today, but we fully expect these rates to change,” said Hon. “It’s actually going to hit flatter ground.”

Hon also said that as of Thursday night, lava was erupting at an estimated rate of 50 to 100 cubic yards per second. Hon used the example of a tractor trailer dump truck to illustrate how much lava that is.

“If you think of ten of those every second delivering a full load of lava -- that’s what’s coming down those channels right now,” he said.

That’s also similar to the peak rate of lava from Fissure 8 during the 2018 Kilauea eruption in Leilani Estates.

Another uncertainty was raised if the flow heads west: could it threaten the Pohakuloa Training Area, and does the military have plans if it does?

“Right now there’s nobody training up there, and that would be the foremost concern,” said Hawaii County Civil Defense Administrator Talmadge Magno during a Facebook Live Q&A session Thursday evening.

“Beyond that, I’m not sure about their plans about their infrastructure and so forth ‚and I wouldn’t want to comment because I don’t know.”

Hon stressed it’s still not certain the lava will reach the highway.

“If it turns to the west, the new highway will be protected from the lava flows, and the lava flows will go along the old highway up to a point until they hit the 1843 lava, and then it would be deflected a little bit toward Mauna Kea,” he said.

A shutdown would have a major impact on thousands of commuters.

Magno said the highway has become the “main transit” between east and west Hawaii Island.

“So it’s very important,” he said.

Magno added if the main highway closes, those seeking to get between Hilo and Kona would need to rely on coastal routes like Highway 19 and Highway 11. “They’re gonna be seeing an increase in traffic and it’s just going to cause congested areas to get more congested, which equates to safety as well,” he said.

Experts said it is also not known how long this eruption will last.

“Typically, these rift eruptions run their course after two to three weeks, but there have been some that have gone over a year and some that are much shorter than that,” Hon said.

“If we saw the amount of lava decreasing rapidly that could be an indication we’re getting towards the end of it.”

If the lava advances closer to the highway, Gov. David Ige said he plans to activate the Hawaii National Guard to help set up critical infrastructure and “support planning for alternative routes.” Ed Sniffen, deputy director of highways for the state Department of Transportation, added that messaging will be posted.

‘Quite an inconvenience’

Kim Rodrigues has been commuting between Hilo and the Waikola area for 19 years.

She said the alternate routes aren’t meant for heavy traffic.

“We’re going to have to be patient,” she said.

Rodrigues wants the state to add temporary, left turn lanes or add passing lanes on the shoulder of Highway 19 to prevent backups if there are Saddle Road closures.

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“It’s going to be quite an inconvenience but it doesn’t mean that our people will be cut off,” said Elena Cabatu, head of marketing at Hilo Medical Center.

The facility has 1,600 employees and a handful of them commute from the west side.

“We are taking an inventory of our employees and where they live,” she said.

Healthcare workers are essential so they will have to make the drive.

Cabatu said they are helping those employees prepare for the added commute time.

Lava diversion discussed

Hawaii Island officials have had very preliminary discussions about whether there’s any possibility to divert the lava flow ― something that has been tried (with limited success) in other places.

Those conversations were not fruitful, Magno said, without elaborating.

At a news conference Wednesday, Ige also said diverting the flow would likely be impossible.

“There is no physical way or technological way to change the course of where the lava flows,” Ige said.

“The power of Mother Nature and Madame Pele overwhelms anything we can do. So we will monitor and make plans to ensure connectivity between east and west should the DK highway get overrun with lava.”

Meanwhile, officials continued to stress the eruption does not pose a threat to downslope communities.

The Mauna Loa eruption started late Sunday after months of elevated earthquake activity.

The 13,681-foot Mauna Loa volcano had been rumbling more in the last several months, prompting many to believe an eruption was imminent. The 1984 Mauna Loa eruption also began within the Mokuaweoweo summit.

For details on volcano hazard zones, click here.

Fissures eventually opened on the mountain’s northeast rift zone, sending lava flows snaking toward the Hilo area. None of the flows reached the outskirts of Hilo by the time the eruption ended, about 20 days after it began.

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This is a developing story. Check back for updates.