HVO: Lava crossing Daniel K. Inouye Highway ‘no longer an immediate concern’

Although the Mauna Loa eruption continues, Daniel K. Inouye Highway was granted a reprieve Thursday when the primary lava flow stopped advancing.

The leading edge of the lava flow reached about 1.7 miles away from the highway by Thursday morning, but David Phillips, deputy scientist in charge for the U.S. Geological Survey’s Hawaiian Volcano Observatory, said it is “no longer an immediate threat” to people or infrastructure and has reached a standstill.

Phillips explained that lava flow channel from Fissure 3, still the only volcanic fissure currently active on Mauna Loa, has been cut off, and lava from the fissure can no longer reach the flow front. Instead, he said, lava is spreading outward from the fissure and covering old lava that had been deposited previously.

“It’s still generating lava flows, but those lava flows are now localized around the fissure,” Phillips said.

Phillips said the flow could still creep forward as the mass of lava cools and settles, but he reiterated that with liquid lava unable to reach the bottom of the flow, it cannot maintain its former pace.

HVO research geologist Frank Trusdell said it also is very unlikely lava from Fissure 3 will be able to “restart” the primary lava flow front, as the fissure appears to be emitting less material.

Trusdell said one possible explanation for the turn of events could be that the fissure itself has constricted, leading to higher fountaining at the fissure itself, but less lava actually being released.

But Trusdell also noted that three previous historical Mauna Loa lava flows had transitioned from producing ‘a‘a lava — the chunkier, more viscous lava that has characterized the current eruption — to producing more fluid pahoehoe lava. This transition, he said, also corresponded with a decrease in effusion rates, suggesting that the current slowdown might herald a new phase in the eruption.

Trusdell said further observations will be necessary to reach a conclusion.

Regardless of the reason why, the flow stalling out should come as a relief to people islandwide after more than a week of wondering if and when the island’s primary transit corridor would be cut off.

“I think we’re all breathing a sigh of relief,” said Miles Yoshioka, executive officer of the Hawaii Island Chamber of Commerce. “I’ve been speaking with truckers, shippers, retailers, and everyone was concerned.”

Yoshioka noted last week that without the highway, commonly called Saddle Road, nearly all cross-island traffic would be routed to Highway 19 along the Hamakua Coast, a 2.5-hour drive under normal circumstances.

“Saddle Road really shrank our island,” Yoshioka said last week.

With the highway seemingly spared for the time being, Mayor Mitch Roth reminded drivers to remain careful and respectful while viewing the lava.

More than 20,000 vehicles have traversed the county’s Traffic Hazard Mitigation Route since it opened last week, and Roth urged drivers to pick up after themselves and to not leave the road.

Hawaiian cultural practitioner Noe Noe Wong-Wilson said the Royal Order of Kamehameha will clean the area around the mitigation route today to “prepare for the arrival of Madame Pele.”

Email Michael Brestovansky at mbrestovansky@hawaiitribune-herald.com.