What Is the Difference Between Pahoehoe Lava and A'a Lava?

One of the primary differences between pahoehoe and a'a lava formations is in terms of texture, where pahoehoe lava is smooth and viscuous while a'a lava is rough and rubbly. Pahoehoe lava also flows and cools down at a much slower rate compared to a'a lava.

Hawaii is home to some of the most active volcanoes in the world. These geographical features cause hot molten material called lava to ooze out from their craters or nearby vents. Two Hawaiian terms have come to designate two main types of basaltic lava flow: pahoehoe and a'a.

Pahoehoe lava generally forms in volcanic areas with gently-sloping sides while a'a lava is prominent in steep-sloped volcanoes, such as the ones in the Galapagos Islands. Pahoehoe lava formations are also associated with numerous flow units and lava tubes while a'a lava is characterized by large channels and a few but sizable flow units.