Laavavirtoina

Laavavirtoina is the Finnish term for lava flows, the surface movement of molten rock expelled by volcanic activity. It describes the emplacement of lava as it travels away from vents or fissures, forming lava fields on the landscape. The phenomenon occurs across a range of magma compositions and eruption styles, from effusive eruptions that release steady lava to brief, vigorous outpourings.

The flow behavior depends on magma viscosity, temperature, gas content, eruption rate, and the slope of the terrain. Two commonly used texture terms to describe surface lava are pāhoehoe, which is smooth and ropy, and ʻaʻā, which is rough and fragmented. Lava can travel as a laminar sheet, within channels, or in lava tubes when a crust forms on the surface and molten interior continues to move. As lava advances, it often builds channels, levees along the margins, and sometimes forms shield-like flows over broad plains.

Deposits and landforms associated with laavavirtoina include lava flows that crystallize to solid rock, crustal cooling features, and features such as crusted roofs in lava tubes. Post-eruption surfaces may show vesicular textures from gas escape and cracks from cooling. The extent and speed of a laavavirtoina event are influenced by topography and vent supply, with potential impacts on nearby settlements, agriculture, and infrastructure.

Monitoring of lava flows uses ground observations, satellite imagery, and geophysical methods to assess reach, advance rate, and hazards. While laavavirtoina describes surface lava movement, it is part of broader volcanic processes that also include explosive activity and pyroclastic phenomena.