Pahoehoelava

Pahoehoelava, commonly referred to as pahoehoe lava, is a type of basaltic lava flow known for its smooth, ropy surface. It forms when low-viscosity magma erupts quietly and travels as a lava flow, allowing a thin crust to form on the surface while the interior remains molten.

As the flow advances, the surface crust is stretched and deformed, creating the characteristic rope-like textures that give pahoehoe its name. The lava can form toes or lobes that advance slowly, and the surface may develop features such as smooth, glassy patches or folded crust. Pahoehoe flows can also develop lava tubes when the molten interior continues to move downstream while the crust remains intact.

Pahoehoelava is distinct from a’a lava, a rough, broken texture. Under certain conditions, pahoehoe can become more viscous and transition into a’a as cooling continues or the flow becomes agitated. Both textures can appear on the same eruption, reflecting variations in temperature, gas content, and slope.

Occurrence and significance: Pahoehoe is common in effusive eruptions of basaltic magma and is widely observed at shield volcanoes, especially in Hawaii (such as Kilauea and Mauna Loa), as well as in other basaltic regions worldwide. The ropy surface and potential for lava tubes make pahoehoe a key feature for interpreting eruption dynamics and lava transport.

Etymology: The term derives from the Hawaiian pāhoehoe, meaning smooth or rope-like surface.