Lava flowing into preexisting cracks and cavities

Lava commonly flows from the surface into preexisting cracks and cavities made during earlier periods of flow emplacement and inflation. Generally the lava cools quickly underground against the cool rock and consequently doesn't advance far. Often, however, reheating of the older rock as far as 20-30 m downstream from the active surface flow makes the ground surface too hot to touch and turns the sides of cracks incandescent. In this image, surface lava is flowing underground, into an inflation cave (tube) formed last summer. Site is at the front of the western lobe on the coastal flat, about 1.4 km from the ranger hut at the end of Chain of Craters Road. Flash used to show details of dark inflation feature.