Hawaii volcano eruption sends ash 5 miles high

Hawaii’s Kilauea volcano erupted explosively early Thursday, tossing boulders hundreds of feet and sending a plume of ash about 30,000 feet into the predawn sky.

A webcam at the Hawaii Volcano Observatory caught the aftermath of the short-lived eruption on film: an onslaught of wet and dusty ash raining down on a darkened landscape. From the summit of Mauna Loa volcano, 20 miles away, cameras photographed an anvil-shaped plume billowing on the horizon.

U.S. Geological Survey scientist Michelle Coombs said the activity at the vent could become more explosive again. “It’s a real dynamic situation up there,” she said of the summit.

Scientists had warned for days about a major eruption as the lava lake that once filled the crater at Kilauea’s summit began draining back into the ground. Their concern was that the sinking molten rock would create steam as it interacted with the water table and that the steam would then jet upward, hurling rocks and ash into the sky in a phenomenon known as a phreatic eruption.

“This is the sort of explosive activity that was anticipated,” Mike Poland, a USGS geophysicist who was based at Kilauea from 2005 to 2015, said Thursday. “It’s not going to be the only one.”

Though dramatic, Thursday’s early eruption did not pose an immediate threat to any people in the vicinity, Poland said. Observatory staff had left their Kilauea location on Wednesday, for a facility at the University of Hawaii in Hilo, after concluding that wind could carry ash toward the station.

According to Poland, the greatest impact was to an area within a few hundred yards of the summit’s eruptive vent. That’s where the explosion would have sent hot gas and 1,000-pound rocks soaring.

But wind is carrying the plume from the eruption northeast, potentially raining ash into nearby communities, the Hawaii Volcano Observatory warned. Depending on weather conditions, USGS said, ash might fall as far as Hilo, 30 miles to the northeast.

The observatory also warned that vog — a noxious smog formed when sulfur dioxide from eruptive vents interacts with water vapor and oxygen in the air — has been reported in the community of Pahala, southwest of the volcano.

Though disruptive and painful for people living near Kilauea, especially those who have already lost their homes, the eruption will not significantly affect life on the rest of the Big Island, Poland said. “And it is not likely to turn into some catastrophic event,” he added.

Kilauea, a massive shield volcano on Hawaii’s Big Island, is the site of the world’s longest ongoing eruption, oozing lava since 1983. But in recent weeks the volcano has become particularly restless. Fissures opened in communities along the volcano’s eastern slopes, prompting evacuations and engulfing dozens of homes in lava.

That activity along the East Rift Zone caused a dramatic depressurization of the magma column below Kilauea’s summit, slowly draining the lava lake in the summit crater.

As the molten rock dropped below the level of the water table, it’s likely that water in the surrounding rock began pouring into the vacated chamber, much the way water rushes to fill a recently dug well, said Charlotte Rowe, a geophysicist at Los Alamos National Laboratory. The water would then flash into steam, “and steam as we know is a very powerful source of energy, a very powerful propellant,” Rowe said.

U.S. GEOLOGICAL SURVEY Sulfur dioxide plumes rise from fissures along the rift of Hawaii’s Kilauea volcano. Thursday’s eruption did not pose an immediate threat to people in the vicinity, officials said.