Kīlauea eruption in Halema‘uma‘u on Jan. 1, 2021

The margins of the lava lake in Halema‘uma‘u are showing a subtle levee around the perimeter. The levees grow from repeated small overflows, and the rafting and piling of pieces of surface crust that fuse together into a barrier that impounds the lake. This results in a "perched" lava lake, and this geometry has been common for lava lakes at Kīlauea's summit and rift zones. For example, see this photo of a perched lava pond within Pu‘u ‘Ō‘ō crater in 2011. USGS photo by M. Patrick