New lava ‘deltas’ in ocean following eruptions are unsafe, Hawaii officials warn

Volcanic eruptions are extending the coastline of Hawaii — but the newly formed lava “deltas” aren’t safe for visitors, state officials warn.

“Lava deltas are landforms built as hot lava enters and is cooled by the ocean,” the Hawaii Department of Land and Natural Resources said in an Aug. 18 news release. “Deltas extend the island shoreline, but the terrain can be deceptive.”

Even once it cools, the formerly molten rock may appear solid but can be thin and unstable, officials said. Vegetation also can conceal deep fissures and cracks.

A video posted by the agency shows a crack going all the way down to the ocean in a lava delta at Kapoho, in the Puna district of Hawaii. It could be a precursor to a collapse.

The department advised visitors to coastal areas in Hawaii to exercise “extreme caution.”

Many of the lava deltas were created by the 2018 eruption of Kilauea, officials said.

“The safety of our residents and visitors is our top priority, and we must emphasize that these newly created lands are not safe to traverse,” Dawn Chang, department chair, said in the release. “The land is still settling and is unpredictable.”

The creation and destruction of lava deltas remain largely unknown, officials said.

“The U.S. Geological Survey notes that a collapsing delta can trigger explosive activity, hurling rocks and debris hundreds of yards inland and/or seaward,” officials said.

“The warning includes, but is not limited to, the communities of Kapoho, Pohoiki, Malama and Kalapana,” officials said.

“The report of the crack at Kapoho is a stark reminder that even years after eruption, areas in the lava flow hazard zones are active and can be dangerous,” Chang said.

This story was originally published August 19, 2025 at 11:25 AM with the headline "New lava ‘deltas’ in ocean following eruptions are unsafe, Hawaii officials warn."