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Volcano Nat Haz - Coggle Diagram
Volcano Nat Haz
Ash columns
Material expelled rapidly from conduit = 3 phases
Ash = fragments of volcanic rock under 2mm
Mix with water = concrete like
Bad for planes/ships
Can lacerate airways if breathed
Some goods
Fertile lands
But can also kill crops
Fragmentation of magma in the system
Liquid phase with dispersed gas bubbles to
Gas phase with dispersed magma fragments (pryoclasts)
Generates the explosive force of volcanic eruption
Potential energy of magma to the kinetic energy of gas phase
Pyroclasts enhanced by thermal expansion of the gas particle within volcanic plumes
Cashman and Scheu 2015
Occurs in 4 ways:
Magma ascends rapidly during explosive eruption
Rapid decompression such as collapse of lava domes
Shearing of magma at conduit walls
Impact-induced explosion of hot solid blocks during dome collapse
Viscosity main control on if fragmentation occurs
High viscosity
Magma resists flow
Rises slowly
Gas cannot escape
Pressure builds
Fragmentation
Sahagian 1999
Bubbles grow quickly magma does not have time to relax
Cannot relax as fluid so behaves like brittle solid that can be broken/stretched
Sudden release of energy propels the gas upwards
High energy = larger plume
Carey and Bursik 2015
pdc
Gravity driven flows
Fragmented magma
Lateral blast
Lava dome collapse
Effusive eruption w sticky lava, forms a cone
Lava flow that doesn't go anywhere
Boiling over
Vesuvius column collapse
6 distinct flows
VEI based on bulk density of material
Could have more gas at VEI 5 than VEI 7
Effusive vs explosive
Transitions between explosive and effusive?