4. Lava

Abstract

‘Lava’ focuses on lava. Within a kilometre or two of the ground surface, the rise of hot magma is accelerated by the growth of gas bubbles which increase the magma’s buoyancy. If the gases can readily escape from the magma, the magma may ascend more slowly without being ripped apart, and it eventually emerges from the volcano as a lava flow. There are many different types of lava flows: pahoehoe, a’a, block-lavas, inflated lavas, and lava domes, which decrepitate to form hazardous ‘block-and-ash flows’.