HILO — Kilauea’s summit was rocked by shallow earthquakes Wednesday as the volcano’s caldera inside Hawaii Volcanoes National Park subsides along with its magma chamber.
The shaking produced minor cracks on Highway 11 near the park entrance and caused damage to other facilities at the park, which remains closed because of the risk of a large steam-driven explosion.
“There was severe shaking at my office,” said Jessica Ferracane, park spokeswoman. “It was really, really heavy.
“Following that, there were cracks not only on Highway 11, but on park roads and at its emergency operations center.”
Geologists say the floor of the caldera, the large crater that contains Halema‘uma‘u and its former lava lake, has subsided 3 feet as its vertical column of molten rock drops in response to the eruption on the East Rift Zone in lower Puna.
The eruption downrift has displaced about 2,000 people and claimed 37 structures since May 3, mainly in Leilani Estates.
Talmadge Magno, Hawaii County Civil Defense administrator, said the cracks in the highway primarily occurred between mile markers 28 and 29 in an area where the road runs within the outer edge of Kilauea’s caldera. He estimated they created a gap of less than an inch, and said the state Department of Transportation will repair as needed.
“We are leaving Highway 11 open at this time, but will close it if it becomes unsafe for motorists,” said park Chief Ranger John Broward in a written statement. The park has jurisdiction over that portion of the highway.
The damage occurred after a magnitude-3.5 earthquake struck at a depth of 0.1 mile beneath the summit at 11:30 a.m. More than two dozen other quakes of similar strength occurred there during a 24-hour period.
Ash emissions continued at the summit Wednesday after the expulsion of a large plume the day before, but with varying intensity. A larger steam-driven explosion that could hurl large boulders remains possible.
Increased earthquake activity and the potential for a larger eruption prompted the Hawaiian Volcano Observatory staff to relocate from their offices at the caldera rim to the University of Hawaii at Hilo, said Michelle Coombs, Alaska Volcano Observatory lead scientist, who is assisting her colleagues in Hawaii with media briefings. She said the staff can monitor the volcano remotely.
Tuesday’s ash emission at the summit was likely the result of rock falling from the side of the crater wall into the receding magma column, but might have been assisted by steam.
“The ash plume emissions are getting stronger in intensity,” said Steve Brantley, deputy scientist-in-charge at HVO. “This is following the script we’ve been talking about for the last few days.”
Tuesday’s ash emission also appeared to have ejected rocks up to 2 feet across within the caldera floor. Larger rocks could be ejected farther if more pressure builds up in the magma column.
Geologists reported little change in the eruption in lower Puna.
Activity remained focused at fissure No. 17, which has produced the largest lava flow yet northeast of Lanipuna Gardens, but the spattering was decreasing. Its flow remained 1.5 miles in length and its advance has slowed significantly.
No flows were active as of 6:30 p.m., according to Civil Defense.
Gov. David Ige announced Wednesday the formation of a dual status command that will give Brig. Gen. Kenneth Hara of the Hawaii National Guard authority to command active military forces to assist with evacuations.
Parts of Hawaii Island got a taste of sulfur dioxide Wednesday morning as a disruption of trade winds caused emissions from the volcanic activity to be swept more inland. Those conditions are expected to ease today, though gas emissions remain dangerously high near the fissures around the Leilani Estates and Lanipuna Gardens subdivisions.
Magno said the Hawaii Fire Department has conducted at least three rescues of people who found themselves at risk as they went back to their homes in evacuated areas.
State Department of Health and U.S. Environmental Protection Agency officials say they are installing more sulfur dioxide monitors around the fissures.
Meanwhile, Civil Defense officials continue to work on deactivating three geothermal wells at Puna Geothermal Venture, which has been encroached upon by the fissures.
David Damby, a research chemist with the U.S. Geological Survey, said quelching has been occurring at the wells, which involves filling them with water to prevent unabated releases of hydrogen sulfide. He said caps will then be placed on the wells to “kill” them. Each cap will take a day to install.
Email Tom Callis at tcallis@hawaiitribune-herald.com.