A section of wall from Halemaumau Crater collapsed Sunday afternoon, triggering a small explosion that sent molten lava spattering across the closed visitor lookout.
The event, which occurred around 1:20 p.m., following a week of elevated levels and periodic overflows that have produced spectacular visuals.
The lava lake remained close to the rim of the Overlook crater throughout the weekend, once overflowing onto the floor of Halemaumau Crater around 5:30 p.m. Saturday.
On Sunday morning the lava level was observed to be just a few yards below the rim of the Overlook crater, according to the Hawaiian Volcano Observatory.
The rise in lava levels has been visible from the national visitor park overlook for the first time since 1974.
The lava lake and its crater formed on March 19, 2008, but until this week only the gas plume and nighttime glow from the vent had been visible.
On April 28 a rockfall at Halemaumau Crater triggered a spectacular explosion that was recorded by observatory cameras.
Rises in the lava lake are typically associated with inflation activity at the summit, although no significant activity was detected over the weekend.
Meanwhile, Hawaiian Volcano Observatory webcams continued to detect nighttime incandescence and daytime smoke, indicating that surface flows from the June 27 lava flow remain active northeast of Puu Oo. The most distant activity was burning forest about 5 miles northeast of the crater.