While there has been a significant slowdown in the surge of lava flowing from fissure 8 into the ocean the past few days, scientists said it is too soon to say yet whether it is coming to an end.
“We can’t be sure,” said USGS Hawaiian Volcano Observatory scientist-in-charge Tina Neal. “Clearly, we’re in a pause or lull, and we just have to wait and watch in coming days and weeks ahead to see whether the system evolves.”
During Monday morning’s helicopter overflight, U.S. Geological Survey crews continued to observe lower levels of lava output from fissure 8. The team saw some lava bubbling within the fissure and a weak gas plume but did not observe lava being actively added to the channel. Ground crews found the upper channel largely devoid of lava.
This followed observations of reduced output of lava Saturday night and Sunday morning.
The eruption began May 3 and has destroyed more than 700 homes while adding new land in and around Kapoho Bay.
Eruptions can wax and wane or pause completely, according to the USGS. Alternatively, a return to high levels of output or new outbreaks could occur at any time.
The pause can last from a few days to a few months, in which case a resumption might be called a new eruption, said Neal. In the 1955 eruption one pause lasted five days and another lasted 16 days.
Big Island Mayor Harry Kim has said the county will not attempt to clear or fix damaged government roads until there is a minimum of six months of inactivity by the lava to ensure that the roads don’t get covered up again.
As the lava flow has slowed, the pattern of daily collapse events at the Kilauea summit has also strayed from the norm of the past few weeks. The last collapse event occurred at about noon Thursday, and the number of earthquakes has also gone down.
Neal said some hints of the slowdown were apparent in mid-July, as the duration between collapse events, which happened between 25 to 30 or more hours apart, began to increase. There were some periods of lower lava effusion and lower lava fountain heights, as well, in the lower East Rift Zone.
Some possible reasons for the pause include a slowdown in the supply of lava to the summit’s magma reservoir, or a blockage somewhere, said Neal. There is no evidence for either scenario at this point.
But the return of regular collapses at the summit can’t be ruled out, she said.
In a mid-July report that USGS prepared for Hawaii County Civil Defense, geologists said the eruption could continue for months or years.
If lava began spewing with vigor from fissure 8 again, it would likely reoccupy the existing channel but could spill in different directions. The cone around fissure 8 could also fall apart, creating new pathways for the lava. The lava could also break out in a different location altogether.
To date, the duration of this eruption, in its 96th day Monday, has surpassed that of the 1955 eruption, which lasted 88 days, not counting pauses. At least 24 separate vents stretching 9 miles from Kapoho to the west of Pahoa-Kalapana Road opened in that eruption.
In the current eruption, 22 separate vents have opened up, but activity eventually coalesced at fissure 8 and the total flow area is at 13.4 square miles.
On Monday there were small, active ooze-outs near the coastline at Kapoho Bay and Ahalanui, but the laze plume had diminished. Though just about 200 yards away, the lava did not appear to be advancing toward Pohoiki boat ramp, which remained intact.
Hawaii County Civil Defense warns the public not to access the flow field due to extreme hazards.
The USGS will not be sending field crews to the East Rift Zone when Hurricane Hector is expected to reach the Big Island late Tuesday through Wednesday, causing winds to reach tropical storm strength. Heavy rain will likely create “whiteout conditions” with dense clouds of steam, reducing visibility, said Neal, but the storm is not expected to affect the volcano.