June 12, 2023 — Crustal foundering at Kīlauea

The lava on the surface of Halema‘uma‘u crater is hot and fluid even though it quickly grows a dark crust. When the crust forms, it becomes denser than the fluid lava below and starts to sink into it. The fluid red lava below forms thin lobes above the sinking crust. We call this process crustal foundering—an overturn of the crust. It only takes seconds before the red exposed lava also crusts over and darkens again. USGS photo by J. Schmith.