A report on Lava, Volcano and Tephra

A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.

Tephra is fragmental material produced by a volcanic eruption regardless of composition, fragment size, or emplacement mechanism.

Lava may be erupted at a volcano or through a fracture in the crust, on land or underwater, usually at temperatures from 800 to 1200 C. The volcanic rock resulting from subsequent cooling is also often called lava.

(An explosive eruption, by contrast, produces a mixture of volcanic ash and other fragments called tephra, not lava flows.) The viscosity of most lava is about that of ketchup, roughly 10,000 to 100,000 times that of water.

When the volcanoes erupted, whole forests growing in Antarctica were covered in lava.

Stratovolcanoes (composite volcanoes) are tall conical mountains composed of lava flows and tephra in alternate layers, the strata that gives rise to the name.