An intrusion of magma into Kilauea’s East Rift Zone shook the ground under lower Puna residents’ feet Tuesday and stirred worries about a new volcanic vent opening near populated areas.
The shallow and mostly minor quakes progressed downrift from the Pu‘u ‘O‘o cone, which was spewing ash following the collapse of its crater floor Monday, to Highway 130, about 10 miles away. Eight were magnitude 3 or greater, with the largest registering a magnitude 4.2 off the southern coast.
The seismic activity appeared to have leveled off later in the day, but geologists and Hawaii County officials were keeping a close watch. As precautions, the county closed the Kalapana lava viewing area to visitors and vendors Tuesday, and Civil Defense planned to keep at least one staff person at the office in Hilo around the clock.
“What we don’t know is if the intrusive event is over, is done and that’s all that’s going to happen or if it’s just paused and might tick back up,” said Janet Babb, Hawaiian Volcano Observatory spokeswoman.
“An intrusion does not always lead to an eruption,” she added, “but intrusions down the lower East Rift Zone have led to magma (reaching the surface) and led to eruptions.”
Babb gave the 1960 eruption that destroyed the village of Kapoho as an example.
The shaking wasn’t the only thing getting geologists’ attention.
Babb said sensors 7.5 and 10 miles downrift of Pu‘u ‘O‘o detected ground deformation, another sign of magma moving underneath. She said magma intruded at least as far downrift as Highway 130.
Additional sensors were placed Tuesday to track changes. More will be deployed today.
A new vent closer to populated areas could displace or threaten many residents, depending on the path of the flow.
During the 2014 lava flow crisis, the county established a coastal emergency route to Hawaii Volcanoes National Park on top of the former Chain of Craters Road, which had been covered by numerous lava flows. Portions of that road have since been reclaimed by the “61g” flow from Pu‘u ‘O‘o.
Talmadge Magno, county Civil Defense administrator, said the county wasn’t making plans to clear another path.
“With the way this activity is, you don’t know if it’s going to come back down on Chain of Craters Road,” he said.
Magno said Civil Defense is talking with first responders and other agencies to ensure their plans are ready. He said the county is working closely with HVO and “watching their instruments.”
Geologists took multiple flights near Pu‘u ‘O‘o on Tuesday, but poor weather conditions and ash from the cone made it hard to get a good look, Babb said.
Red ash was seen blanketing the ground nearby.
Pressure under the cone began building in mid-March, leading geologists to estimate a new vent might open there.
The magma then drained away and pushed farther into the rift zone, causing the crater floor to collapse Monday. Multiple collapses have occurred during the 35-year-old eruption, including one in 2011.
Babb said the eruption at Kilauea’s summit appeared not to be affected and its lava lake in Hawaii Volcanoes National Park remained high.
Mark Hinshaw of Kalapana Seaview said he wasn’t worrying about the change in volcanic activity yet.
It’s part of life for lower Puna residents, as highlighted by the “June 27th” lava flow that threatened Pahoa nearly four years ago, he noted.
“We just got to get used to it,” Hinshaw said. “If it happens, it happens.”
Current alerts can be viewed at https://volcanoes.usgs.gov/volcanoes/kilauea/status.html or www.hawaiicounty.gov/civil-defense.
Email Tom Callis at firstname.lastname@example.org.