Tulovirroille

Tulovirroille is a term found in some Finnish-language sources referring to a network of surface lava channels that develop during effusive volcanic eruptions. In mainstream volcanology, the same features are typically described as lava channels or pahoehoe flow fields, with cave-like lava tubes and crust-rimmed channels forming as lava travels.

Formation and morphology: As low-viscosity lava erupts and advances, a solid crust can form on the surface, while the interior continues to flow. The crust may crack and channel the molten lava, creating sinuous conduits called tulovirroille. These channels may be characterized by raised levees along their margins, a smooth or ribbed crust, and, where preserved, associated shallow lava tubes or skylights.

Distribution and examples: Lava channels of this type are most commonly reported in basaltic shield-volcano fields and large effusive eruptions, such as those observed in Hawaii and Iceland, though terminology varies by region. The term tulovirroille is not universally applied and is more common in local or historical Finnish-language literature.

Significance: Studying these channels helps reconstruct flow paths and eruption dynamics, contributing to hazard assessment and volcanic stratigraphy. When preserved in solidified flows, tulovirroille beds can provide records of flow velocity and crust-formation processes.

Ecology and preservation: Ultra-high temperatures and mineral-rich fluids limit life within these channels, but microbial communities can inhabit cooler, crusted sections or later-stabilized deposits in cooled lava fields.

See also: Lava channel, Lava tube, Pahoehoe, Volcanology.