: Paleoclimatology: explosive volcanism

natural phenomenon > geological phenomenon > volcanism > explosive volcanism

explosive volcanism

In volcanology, an explosive eruption is a volcanic eruption of the most violent type. A notable example is the 1980 eruption of Mount St. Helens. Such eruptions result when sufficient gas has dissolved under pressure within a viscous magma such that expelled lava violently froths into volcanic ash when pressure is suddenly lowered at the vent. Sometimes a lava plug will block the conduit to the summit, and when this occurs, eruptions are more violent. Explosive eruptions can expel as much as 1,000 kg (2,200 lb) per second of rocks, dust, gas and pyroclastic material, averaged over the duration of eruption, that travels at several hundred meters per second as high as 20 km (12 mi) into the atmosphere. This cloud may subsequently collapse, creating a fast-moving pyroclastic flow of hot volcanic matter. Viscous magmas cool beneath the surface before they erupt. As they do this, bubbles exsolve from the magma. Because the magma is viscous, the bubbles remain trapped in the magma. As the magma nears the surface, the bubbles and thus the magma increase in volume. The pressure of the magma builds until the blockage is blasted out in an explosive eruption through the weakest point in the cone, usually the crater. (Adapted from: https://en.wikipedia.org/wiki/Explosive_eruption)

http://data.loterre.fr/ark:/67375/QX8-6Z6P1ZGD-F

RDF/XML TURTLE JSON-LD Last modified 6/5/24

Loterre