Volcano Watch: Why is the 2018 lava still so hot?

Two HVO geologists document road cutting activities on Highway 132 on Aug. 7. One geologist is taking visual photographs while another geologist is taking thermal photographs to make a tandem pair for comparison. The temperature of the solidified lava was measured to 425° C (800° F) at the digging site. (Courtesy photo/by USGS geologist K. Mulliken)

HILO — As roads are recut into Kilauea’s 2018 lava flow field, many have been surprised at how hot the lava remains under the surface, even though it is solidified. Why is it still so hot? The short and simple answer is that lava insulates itself very well.