Nature of vulcanicity and its relation to plate tectonics Flashcards
vulcanicity at destructive plate margins
the subduction at the plate margin result in volcanic activity when oceanic crust dips below continental temps rise due to increased depth and melting occurs
resulting magma moves slowly to surface and erupts
vulcanicity at constructive plate margins?
tension in the crust and lithosphere reduces pressure and allows magma to flow to surface
what are the primary effects of volcanic eruptions?
tephra
pyroclastic flows
lava flows
volcanic gasses
what are the secondary effects of volcanic eruptions?
volcanic mudflows
flooding
acid rain
what is tephra?
volcanic bombs and ash are ejected into the atomosphere
what are pyroclastic flows?
gas and tephra which are extremeley hot (over 8000 degrees c ) flow down the side of the volcano at speeds of 700km per hour
what aree lava flows?
flow of molten rock pour from an erupting vent the speed at which lava moves depends on the type of lava
what are volcanic gasses?
carbon dioxide carbon monoxide sulphur dioxide and chlorine eascape from fumeroles
What are volcanic mud flows (lahars)
combination of melted snow ice, rock, sand and volcanic ash
capable of flowing at high speeds over long distances
what is flooding?
serious floodingcan result when eruptions melt glaciers and ice caps
what is acid rain?
volcanoes emit gasses which include sulphur this combines with atmospheric moitsure to form acid rain
what is the main measurement of magnitude?
mian measurement of magnitude is the volcanic explositivity index (vei) a logarithmic scale running from 0-8
what do methods of prediction involve?
- monitoring land swelling
- changes to groundwater levels
- chemical composition of groundwater
- gas emmissions
- expanding cracks
describe the global distribution of active volcanoes
located in long chains along destructive and constructive plate boundaries
