AA-LAVA

AA-LAVA (DE: Aa-Lava; FR: aa-lave; ES: aa-lava; RU: аа-лава), from ʻaʻā in Hawaiian language, the type of the lava stream, which has been torn into the separate parts (blocks) with rough clinkery dross at the surface. It is typical for the basalts of the medium and low viscosity, and is found everywhere, sometimes together with the flows of undulated (pāhoehoe) lava in the same effusive eruption, but with greater (up to 4.5-6 metres) thickness.

It differs from the typical block lavas by the lesser sizes of the fragments (less than 1 metre in diameter are common, up to 1.5 metres are rare), and by their uneven surface. It is characteristic for the oceanic shield volcanoes, and continental eruptions of the volcanic plateaus (Hawaii and Iceland).