NPS Investigates Sulfur Smells in Kalaupapa Crater

The smell of sulfur around the lake in Kalaupapa National Historical Park’s (KNHP’s) Kauhako crater has worried some of the settlement’s residents, but National Park Service (NPS) scientists say the peninsula is not in danger.

Recent studies suggest the crater’s lake may have undergone an “overturning” event, in which hydrogen sulfide (H2S) gas locked in the water’s deepest layers was released, according to NPS Biological Science Technician Kim Tice. This could have been caused by a small landslide or a thinning of the lake’s top layer because of drought conditions, she said.

Visitors to the crater noticed the smell as early as Sept. 28, Tice said during a presentation at Kalaupapa’s community meeting last week.

Heavier than oxygen, H2S should sit at the bottom of the crater, Tice said. If any were to escape above the crater, it would be quickly blown away by trade winds. 

“None of the safety experts I’ve talked to say the community is at any risk,” Tice said. “This event doesn’t suggest anything about volcanic activity.”

Still, several residents said before and during the presentation that the reports of sulfur smell are of concern.

“You cannot tell the people, ‘don’t get upset about this,’ because some people, it bothers them,” said patient-resident Gloria Marks.

NPS has closed the trail into the crater and will continue talking to national experts and monitoring the lake in the coming months. NPS Terrestrial Ecologist Paul Hosten has been in touch with representatives from the U.S. Geological Survey about a potential visit, he said, and NPS plans to invest in H2S-measuring equipment in the coming weeks.

Kauhako crater and Kalaupapa peninsula were formed about 230,000 years ago by the volcano Pu`u `Uao, according to Tice’s report. The lake, formed at the center of the 420-foot tall crater, is the fourth deepest in the United States at about 830 feet, she said.

The lake’s top layer, made of a mixture of fresh and salt water containing oxygen, generally maintains a depth of about 10 feet, according to scientists. The underlying layer is marine water that is anaerobic, or without oxygen, and produces H2S.

Although the lake was once believed to have been connected to the Pacific Ocean, tides and other evidence suggest there is currently no open connection to the sea, according to Tice.

Tice and residents agreed there is no record or memory of a similar sulfur smell. Some questioned the spiritual implications of the unusual event.

“I think that our life is at stake … to think this is the first time this has happened at Kalaupapa,” Marks said. “I think this is a sign … and we should be prepared.”