Lava flows from the eruption of Hawaii's Mauna Loa, the world's largest active volcano, are moving toward a main highway, adding to local worries on an island with few major roadways.
The U.S. Geological Survey confirmed in its most recent update, issued Thursday night local time, that the lava flows "are traveling to the north toward the Daniel K. Inouye Highway (Saddle Road) but have reached relatively flatter ground and have slowed down significantly as expected."
The highway connects the east and west sides of the Big Island, acting as a thoroughfare between the towns of Hilo and Kona.
The lava is traveling toward the highway at a rate of about 0.025 mph and, as of 1 p.m. local time Thursday, the flow front was about 3.2 miles from the highway, the agency's most recent update said.
That rate means the flow could reach the highway in about a week, but that timeline could change, according to the update, which notes that "there are many variables at play and both the direction and timing of flow advance are fluid and are expected to change over periods of hours to days."
A blockage of the road would pose problems, especially for those who use it to commute from Hilo and other parts of the island’s east side, where housing is generally more affordable, to jobs on the west side, home to many of the larger beach resorts. Hilo is also home to the Hilo Medical Center, which employs 1,600 people, some of whom come from the west side, NBC affiliate KHNL of Hawaii reported.
“We have such limited roadways on this island and any time we lose a roadway, it just shifts all that traffic to somewhere else,” Mike Brown, a Kona resident, told NBC News.
Unless some sort of bypass is constructed, commuters would need to take coastal routes to and from Kailua-Kona, adding at least an hour of extra driving each way.
Hawaii Gov. David Ige has issued an emergency proclamation to allow responders to arrive quickly or limit access as needed.
If lava does cross the highway, the Hawaii National Guard can help plan for alternatives and try to set up bypass routes, he said.
Hayley Hina Barcia, who lives in Hilo and has family in Kona, on the west side of the island, said her family relies on the highway to see one another.
“We’re looking to have to go several hours longer to go the south way or taking the north road.”
Sky Makai, a Hilo resident who works in Kona, said the highway blockage would make commuting to work “way harder.”
“I don’t know many people who have a four-hour commute, eight hours in a day,” he said. “So just trying to imagine that is pretty hard.”
Hawaii lava flows generally move slow enough to be avoidable, but they can be destructive, according to the USGS: “They can destroy everything in their paths, including vegetation and infrastructure —which can cut off road access and utilities.”
Lava flows can also cause “severe burns, abrasions, and lacerations upon contact with unprotected or exposed skin” and impact air quality by giving rise to hot temperatures and limited visibility after heavy rain, it states.
Mauna Loa, which means “long mountain,” covers half the island, according to the agency.
In about half of the previous eruptions, the lava remained in the summit region, which rises about 55,700 feet above its base. In the other cases, the lava spilled over into one of the rift zones, producing flows that covered broad swaths of the volcano’s lower slopes.
Before Sunday, geologists had recorded 33 eruptions since 1843, making Mauna Loa among the world’s most active volcanoes. It is one of six volcanoes in Hawaii, according to the USGS.
When the volcano last erupted in 1984, a fast-moving river of lava came within 2 miles of Kulani Prison before it stalled, according to the National Park Service.
A few days later, another lava flow that had moved 16 miles in just four days reached the outskirts of Hilo before stopping, sparing the city, the agency reported.