Why is Water in Kilauea’s Crater?

Aug 23, 2019

A helicopter pilot flying over Kilauea recently found something unusual. There was water in the main crater, and that discovery has sparked a lot of questions.

A little over three weeks ago, a helicopter pilot doing laser mapping for Hawaiian Volcano Observatory spotted a green area at the bottom of Halema'uma'u Crater, around 1500  feet deep. HVO geophysicist Jim Kauahikaua says they believe it's around 227,000 gallons of water, rising about three feet a week. It could be coming from two sources.

"One is that it's just rainfall collecting down there. The other is that this is actually the water table that was there, but got dragged down with the collapses of 2018. And it is now just rebounding after the collapse."

The water is a milky green color — perhaps created by absorption of sulphur gas — and it's hot, around 160 degrees Fahrenheit.

Some have expressed concern about whether the water could lead to an explosive eruption. Kauahikaua says that's not likely right now.

"Two things must occur before eruptions will go to big explosivity. That is: magma rises very quickly, which we haven't seen for the last two centuries, and this water lake. Now, we're getting a water lake, but that still isn't enough to have explosive eruptions, we still need that rapid magma rise."

Kauhikaua says a webcam is now pointed at the lake. Hawaiian Volcano Observatory is working with Hawaii Volcanoes National Park and pilots of drones and helicopters to see how best to get a water sample to answer many open questions.