The growing pool of water in Halema‘uma‘u crater could potentially rise another 180 feet, a Hawaiian Volcano Observatory geologist told County Council members Tuesday.
During Tuesday’s meeting of the council Committee on Agriculture, Water, Energy and Environmental Management, South Kona/Ka‘u Councilwoman Maile David requested a presentation about the status of the new crater lake, which was first observed in July.
“I felt it would be useful and informative to hear from (the U.S. Geological Survey),” David said.
The pool, said HVO geologist Matt Patrick, formed because the extremely high seismic activity at Kilauea summit during last year’s eruption dropped the crater floor below the summit’s water table.
Before the eruption, the presence of lava in Halema‘uma‘u crater heated the rock around the crater floor too much for water to infiltrate the lava conduit. But now that the lava and crater floor have receded, water is steadily seeping into the crater, Patrick said.
The lake was first observed July 25, and was less than about 32 feet wide, Patrick said. Presently, the pool has grown to more than 520 feet long, is rising at a rate of 5-6 inches per day and is estimated to be about 60 feet deep.
Heat from the volcano heats the water to nearly 160 degrees, while the pool absorbs volcanic gases such as sulfur dioxide, staining the water a yellow-green.
It is possible the lake will continue to expand until it reaches equilibrium with the surrounding water table, Patrick said, which means it could rise another 50-60 yards, or 150-180 feet.
Patrick said HVO and USGS will continue to monitor the development of the lake, as it could pose risks to the surrounding area: If lava returns to the summit, he explained, it would likely evaporate the lake in a steam explosion.
However, any such explosion would likely be preceded by several warning signs, Patrick said. Smaller gas explosions might still occur with little warning, but will pose little danger to the area.
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