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Mauna Loa eruption threatens route between Hilo and Kona

Saddle Road, the main thoroughfare between Hilo and Kona, now lies only three miles from the lava but may get a longer than expected reprieve from closure as the lava’s advance slows.

HONOLULU (CN) — The rate of lava flow from Mauna Loa may have reduced significantly since the volcano first erupted this week, but there is still concern that the lava will block a key Big Island highway.

Daniel K. Inouye Highway, named for the late U.S. senator and known locally as Saddle Road, is currently operational, with traffic flowing normally between Hilo in the east and Kona in the west.

The furthest extent of the lava flow is now only around three miles south of the highway, but has slowed significantly as it has hit a relatively low-sloping area. According to the Hawaii Volcano Observatory, the lava’s advance has slowed to a rate of 0.025 miles per hour.

While earlier estimates had placed a potential touchdown onto Saddle Road by Friday at the earliest, scientists are now saying that it may take up to a week for the lava to hit the highway, if at all.

Ken Hon, scientist in charge of the U.S. Geological Survey’s Hawaii Volcano Observatory, said in a briefing Thursday morning that lava’s current position on flat ground will cause the lava to spread out and inflate, reducing speed of the flow toward Saddle Road.

“We’re right on the divide of the lava moving to the east and west sides of the island, we don’t really know which way the lava flow will ultimately go. There’s a lot of uncertainty here; the thing we can say is that this kind of rate it would take at least a week for it to reach the highway,” he said.

Hon said the lava will likely come out in lobes as this happens, at varying unpredictable speeds. He and other HVO scientists are also keeping an eye on a separate lobe coming from a secondary fissure that may affect the dominant flow of lava.

The highway is the most direct route between the Big Island’s two largest cities, letting drivers cross the entire island in an hour and half. Alternate routes along the coastline exist, but at almost double the travel time. Commuters between the east and west of the island rely on Saddle Road as the alternate routes are typically unable to handle heavier traffic.

The Hawaii County Civil Defense Agency has plans for managing traffic should Saddle Road need to be closed.

“Despite the fact that the lava has slowed, we continue to work with different industries and partners in case it gets taken out, how we’re going to work out transport around the island, specifically working with the observatories up on Mauna Kea and the shipping industry,” the agency's administrator Talmadge Magno said.

Magno also discussed opening Old Saddle Road to alleviate some of the traffic congestion from the droves of volcano viewers who have come out to get their own glimpse of Pele, Hawaiian goddess of volcanoes, at work.

Hon emphasized the volatility of volcanoes, saying that there is no real way to forecast the volcano’s total output or the way the lava flow will behave. Two active fissures still feed the flow.

Based on previous eruptions, experts say Mauna Loa will likely continue to erupt for a week or two, although there is no way to know for sure if it could end within days or in a year.

“There’s a lot of variability that can happen out there; none of this is ‘set in stone,' or at least our stone is very liquid and pliable at the moment,” Hon said.   

Despite this, HVO experts have predicted that the eruption is unlikely to pose a significant danger to the general population and expect the lava will remain contained to the Mauna Loa’s Northeast Rift Zone. No downslope populations are currently threatened and Volcanoes National Park remains open to visitors.

Only the U.S. military’s Pohakuloa Training Area, the nearest site to the eruption, may be threatened if the lava pushes out toward it as the lava settles on the flatter ground. Representatives from PTA does not expect the lava will threaten people or buildings onsite. Base operations are continuing as usual.

The Hawaii State Department of Health continues to advise volcano enthusiasts to exercise caution and to wear a mask to prevent inhalation of ash and shreds of volcanic glass known as Pele’s Hair as winds may shift south. Masks, however, the department cautions, will not protect from sulfur dioxide and other harmful gases coming from Mauna Loa.

Mauna Loa first erupted Sunday around midnight, after several months of seismic unrest that put the island on alert for potential imminent eruption. The volcano last erupted in 1984, when lava flow nearly threatened Hilo.

Mauna Loa’s eruption has created a unique phenomenon in the form of dual Big Island eruptions, from both Mauna Loa and Kilauea, which has been continuously erupting since 2021. The dual eruptions are accompanied by snowfall on Mauna Kea, which hosts several large telescopes and has not erupted for several thousands years.

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