ESS 106 Exam 2
VEI - correct answer ✔✔scale to measure explosions by volume
eruptions caused by - correct answer ✔✔interplay between density changes and viscosity
(temperature, viscosity, and rate/style of degassing)
viscosity - correct answer ✔✔measure of difficulty/resistance to flow
based on chemical bonding of melt
magma composition - correct answer ✔✔melt composition, gas content, crystals, silica
variation of silica in magma - correct answer ✔✔determines viscosity level
melt structure (magma) - correct answer ✔✔no long range order, bonds continually being broken and
formed, silica is abundant
silica - correct answer ✔✔Si (cation) and O (anion)
building block of magma
forms tetrahedron that can form chains
decrease viscosity - correct answer ✔✔add water
depolymerizes the melt/tetrahedron form of silica
VSY: high temp - correct answer ✔✔low viscosity
VSY: high gas content - correct answer ✔✔low viscosity
, VSY: a lot of bubbles and crystals - correct answer ✔✔high viscosity
how to measure gases - correct answer ✔✔direct measurements & remote sensing (COSPEC and TOMS)
fragmentation - correct answer ✔✔transition of a bubbly magma to a dismembered froth of magma
clumped in hot gas
more fragmentation = more explosive
explosive eruptions - correct answer ✔✔gas thrust, convective ascent/thrust, umbrella region
pyroclastic surge blast deposits - correct answer ✔✔constrained by topography
cross bedded layers (stratified)
explosive deposits - correct answer ✔✔1) convecting column (tephra fallout)
2) collapsing column (pyroclastic flows)
eruptions column - correct answer ✔✔droplets of molten and glass particles
crystals
country rock/wallrock (lithic fragments)
gas thrust region - correct answer ✔✔100 m/s in strombolian/hawaiian
>600 m/s for Plinian
pryoclasts and gas jetted into atmosphere 10^2-^3 meters high
convective ascent region - correct answer ✔✔air is heated and resulting expansions decreases bulk
density of mixture
10s of km upward
velocity varies from 10-100 m/s
VEI - correct answer ✔✔scale to measure explosions by volume
eruptions caused by - correct answer ✔✔interplay between density changes and viscosity
(temperature, viscosity, and rate/style of degassing)
viscosity - correct answer ✔✔measure of difficulty/resistance to flow
based on chemical bonding of melt
magma composition - correct answer ✔✔melt composition, gas content, crystals, silica
variation of silica in magma - correct answer ✔✔determines viscosity level
melt structure (magma) - correct answer ✔✔no long range order, bonds continually being broken and
formed, silica is abundant
silica - correct answer ✔✔Si (cation) and O (anion)
building block of magma
forms tetrahedron that can form chains
decrease viscosity - correct answer ✔✔add water
depolymerizes the melt/tetrahedron form of silica
VSY: high temp - correct answer ✔✔low viscosity
VSY: high gas content - correct answer ✔✔low viscosity
, VSY: a lot of bubbles and crystals - correct answer ✔✔high viscosity
how to measure gases - correct answer ✔✔direct measurements & remote sensing (COSPEC and TOMS)
fragmentation - correct answer ✔✔transition of a bubbly magma to a dismembered froth of magma
clumped in hot gas
more fragmentation = more explosive
explosive eruptions - correct answer ✔✔gas thrust, convective ascent/thrust, umbrella region
pyroclastic surge blast deposits - correct answer ✔✔constrained by topography
cross bedded layers (stratified)
explosive deposits - correct answer ✔✔1) convecting column (tephra fallout)
2) collapsing column (pyroclastic flows)
eruptions column - correct answer ✔✔droplets of molten and glass particles
crystals
country rock/wallrock (lithic fragments)
gas thrust region - correct answer ✔✔100 m/s in strombolian/hawaiian
>600 m/s for Plinian
pryoclasts and gas jetted into atmosphere 10^2-^3 meters high
convective ascent region - correct answer ✔✔air is heated and resulting expansions decreases bulk
density of mixture
10s of km upward
velocity varies from 10-100 m/s
