HILO — Hawaii Island residents will have only one volcano to worry about. At least for now.
The U.S. Geological Survey lowered the alert level for Mauna Loa on Thursday from “advisory” to “normal” as seismic activity returns to background levels.
USGS’ Hawaiian Volcano Observatory raised the level nearly three years ago as the volcano showed signs of awakening from its slumber. From 2014 through 2017, geologists measured higher rates of shallow earthquakes and ground deformation consistent with magma entering the volcano’s shallow reservoir.
But geologists say seismic activity has been at background levels for the past six months and the threat of an eruption has been reduced.
Asta Miklius, HVO geophysicist, said the magma will be stored until it cools or becomes part of the next eruption.
“If magma is still available, we might not want to rely on having a long period of increased seismicity before the next eruption,” she said. “But, in any case, we are watching it very closely. We will see seismicity and deformation as magma moves to the surface.”
A similar period of elevated activity occurred from 2004 to 2009 without an eruption.
Mauna Loa’s last eruption began March 25, 1984, and lasted a little more than three weeks. It was centered on the volcano’s northeast rift zone and sent lava flowing toward Hilo.
Meanwhile, Kilauea has been erupting almost continuously since 1983 and continues to pour lava out of fissures on the lower East Rift Zone as it has for the past 7 weeks.
Miklius said Mauna Loa and Kilauea have separate magma systems.
“There can be pressure pulses one volcano feels from the other,” she said. “In this case as of right now there’s no effect we can see from Kilauea acting on Mauna Loa’s magma system.”
The official count of homes destroyed from the current eruption reached 598 Thursday but is expected to increase.
Mike Zoeller, a University of Hawaii at Hilo geologist, said fissure 8 was fountaining at heights of 50 meters (164 feet) to 55 meters (180 feet). The lava delta, formed by molten rock flowing into the ocean at Kapoho, was 370 acres in size.
He said lava was reaching areas where the water was up to 60 meters (196 feet) deep.
Zoeller said geologists are now calling the daily explosive events at Kilauea’s summit “collapse explosions.” Those occur as the caldera continues to subside along with the withdrawal of magma.
“They are really a mix of different processes going on,” he said. “We’re not 100 percent sure if the explosion triggers the collapse or vice versa.”
The Los Angeles Times reported Thursday that the Trump administration is tightening its rules regarding USGS scientists talking to reporters. The article said they need prior approval from the U.S. Department of Interior before talking to major outlets.
Leslie Gordon, a USGS public information officer, said the decree won’t impact media access or the response to the ongoing eruption.
“I think the department realizes this is an urgent situation,” she said. “We have people’s livelihoods in danger, people have lost their homes and so it will not affect what we’re doing here regarding Kilauea volcano.”
Email Tom Callis at tcallis@hawaiitribune-herald.com.