Volcanic Eruption

VOLCANIC ERUPTION__________________________________________

Mechanism of destruction:-

Gradual or explosive eruption, ejecting hot ashes, pyroclastic flows, gases and dust. Blast pressures may destroy structures, forests and infrastructure close to the volcano and noxious gases may kill. Hot ash falls for many kilometers around the volcano, burning and burying settlements. Dust may carry for long distances, and fall as a pollutant on other settlements further away. Molten lava is released from the volcanic crater and may flow for many kilometers before solidifying. The heat of lava will burn most things in its path. Snow-capped volcanoes suffer ice-melt causing debris flows and landslides that can bury buildings. A volcanic eruption may alter the regional weather patterns, and destroy local ecology. Volcanoes may also cause ground upheaval during their formation.

Parameters of severity:-

Volume of material ejected. Explosiveness and duration of eruption, radius of fall-out, and depth of ash deposit.

Causes:-

Ejection of magma from deep in the earth, associated with mantle convection currents: Tectonic processes of continental drift and plate formation.

Hazard assessment and mapping techniques:-

Identification of active volcanoes readily identifiable by their topographical and geological characteristics Activity rates from historical records and geological analysis. Seismic observation can determine whether a volcano is active.

Potential for reducing hazard:-

Lava flows and debris flows may be channeled, dammed and diverted away from settlements to