Spectacular view of glowing lava draws thousands to Hawaiian island

The world's largest volcano oozed rivers of glowing lava Wednesday, drawing thousands of awestruck viewers who jammed a Hawaii highway that could soon be covered by the flow.

Mauna Loa awoke from its 38-year slumber Sunday, causing volcanic ash and debris to drift down from the sky.

A main highway linking towns on the East and West Coasts of the Big Island became an impromptu viewing point, with thousands of cars jamming the highway near Volcanoes National Park.

Anne Andersen left her overnight shift as a nurse to see the spectacle Wednesday, afraid that the road would soon be closed.

"It's Mother Nature showing us her face," she said, as the volcano belched gas on the horizon. "It's pretty exciting."

The lava was tumbling slowly down the slope and was about 10 kilometres from the highway known as Saddle Road. It was not clear when, or if, it would cover the road, which runs through old lava flows.

The road bisects the island and connects the cities of Hilo in the East and Kailua-Kona in the West. People travelling between them would need to take a longer coastal road if Saddle Road becomes impassable, adding several hours of drive time.

Ken Hon, the scientist in charge at the Hawaiian Volcano Observatory, said at the current flow rate, the soonest the lava would get to the road is two days, but it will likely take longer.

"As the lava flow spreads out, it will probably interfere with its own progress," Hon said.

Mauna Loa last erupted in 1984. The current eruption is its 34th since written record keeping began in 1843.

Its smaller volcanic neighbour, Kilauea, has been erupting since September 2021, so visitors to the national park were treated to the rare sight of two simultaneous eruptive events: the glow from Kilauea's lava lake and lava from a Mauna Loa fissure.

Officials were initially concerned that lava flowing down Mauna Loa would head toward the community of South Kona, but scientists later assured the public the eruption had migrated to a rift zone on the volcano's northeast flank and wasn't threatening communities.

The smell of volcanic gases and sulfur was thick along Saddle Road, where people watched the wide stream of lava creep closer.

Gov. David Ige issued an emergency proclamation to allow responders to arrive quickly or limit access as needed.

"There is no physical way or technological way to change the course of where the lava flows," Ige told a news conference. He remembers wishing that could have been done in 2018, when an eruption from Kilauea sent lava pouring across homes, farms and roads.

Lava crossed the Mauna Loa Observatory access road Monday night and cut off power to the facility, Hon said. It's the world's premier station that measures heat-trapping carbon dioxide in the atmosphere.

The federal government is looking for a temporary alternate site on the Hawaiian island and is contemplating flying a generator to the observatory to get its power back so it can take measurements again.

Meanwhile, scientists are trying to measure the gas emitted from the eruption.