In the first thermal map (December 21, 2020), the lake area is about 33 acres. In the last thermal map (December 30, 2020), the lake is about 82 acres. The dimensions of the lava lake are now 875 yd on the E-W axis (7+ football fields) and 580 yd on the N-S axis. In the center of the lake, is a 7-acre raft/island (blue color) that rises above the surrounding lake surface by 20-26 ft. The raft moves with lake currents and is likely material erupted early in this eruption that accumulated at the base of Halema‘uma‘u crater. In addition to the raft/island there are ~10 or so small islands visible on the east end of the lake.
The scale of the thermal map ranges from blue to red, with blue colors indicative of cooler temperatures and red colors indicative of warmer temperatures. The western fissures and [now submerged] northern fissures are red in color. A blue rim is visible along the lake margin beginning December 26. This is a narrow ledge of cooled lava (a “bathtub ring”) about 1-2 yards above the lava lake surface.
Hawaiian Volcano Observatory scientists conduct periodic helicopter overflights of Halema’uma’u crater to acquire visual and thermal imagery during this eruption. Imagery is used to create maps and assess hazards. USGS maps by M. Patrick.