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volcanoes - Coggle Diagram
volcanoes
eruption=one way for earths enery to manyfest
volcano: fissure or opening in crust, contain magma
hot gases, lava, rock fragments ejected
magma(molten rocks, crystals, gas(water vapor, CO2))
border areas of lithospheric plates, movements of plates, the conditions for the rising of magma can occur
gas free magma that overflows from crater: lava
On way through lithosphere, magma collects in a reservoir: magmatic chamber.
rises along chimney
release of gases and lava: eruption
champagne effect
type of eruption based on viscosity of magma
more viscous, less readily flows, more trapped gases
based on silica contents & gas contents
basic-type magma, less than 50% silica
acidic-type 50%-70%
lighter color
expultion of pyroplastics(volcanic bombs, pumice, lapilli, ashes)
chemical comp: sich in silica, more viscouse than rich in iron & magnesium
temp: lower, more viscous
presence of solids: crystals increace friction, more viscous
effusive(quiet, possible to live)
explosive(can cause real cataclysms)
gases free themselves from magma
no thrust from gasses, lava just flows
basic magma from great depth of mantle rise in form of column(plumes)
hot spot
pillow lavas(lava cooled in water quickly)
neck/volcanic plug remains sometimes->made of solid lava
volcanic shapes depend on type of lava and way of emmition
shield volcano
form when basic magma flows out of a central chimney
strato
when magma has an intermediate composition between acidic and basic.
scoria cones
after explosive eruption
calderas
following the explosion and partial emptying of the magma chamber
VEI index
volcanic explosivity index
violence of eruption(quantity of mats emitted, their fragmentation & dispersion in surrounding area)
volcani attivi(attività eruttiva recente)
estinti(almeno 10.000 anni)
quiescenti(riposo, ma rischiosi)
volcanic risk
prevention(reduction of settlements, contingency plans)
prediction(tremors, fractures, deformation, variation in chem comp &/or water level)