Topics
Topic Review for Comprehensive Exam -- Spring 2003
Numbers and Locations of "active" volcanoes
a) The several definitions of an "active" volcano
b) Growth of number of "active" volcanoes through human history
c) Geographic distribution of "active" volcanoes
d) Locations of volcanoes relative to plate boundaries
e) Elevations of volcano summits relative to sea level; why are volcanoes not the highest mountains on Earth, as they are on Mars and Venus?
Physical properties of magma and lava
a) Temperature
i. Methods of measurement
ii. Observed ranges
iii. Constraints from experiments
b) Thermal conductivity of magmas and rocks
c) Heat capacity and enthalpy
d) Densities and compressibilities of magmas and rocks
e) Viscosities and yield strengths of magmas and rocks
f) Surface tension of lava in contact with water, air, and gas bubbles
g) Information from lava lakes
Dynamics of flowing lava
a) Boundary conditions for laminar versus turbulent flow
b) Boundary conditions for convective versus conductive heat loss
c) The flow of lava
i. Central vent versus fissure eruptions
ii. Pahoehoe, aa, and blocky lavas
iii. How lava flows grow (by getting longer, rather than wider or thicker)
iv. A paradox; some of the longest lava flows are rhyolitic!
v. Spatter cones and ramparts
vi. Lava domes and spines
vii. Ramps, pressure ridges, accretionary lava balls
viii. Interaction of lava with surface water; the Leydenfrost effect
xi. Pillow lavas and hyaloclastites
Release of gas from magma and lava
a) Compositions of gases
b) Gas solubilities in magmas
c) Bubble nucleation, growth, accretion, ascent, and escape
d) Formation of vesicles, scoria, reticulite, pumice, shards, Pele's hair, Pele's tears
e) Regimes of gas + liquid flow; lava fountains
Pyroclastic eruptions
a) Magnitude, intensity,a nd violence of eruptions
b) Pyroclastic fragments classified by size and shape, composition, and genesis
i. Magmatic explosions
ii. Vitric, lithic, crystal
iii. Juvenile (essential), accessory (cognate), accidental
c) Fragmentation by
i. Magmatic explosions
ii. Phreatic explosions
iii. Phreatomagmatic explosions
iv. Chill-shattering
v. Flow-shattering
vi. Epiclasis
d) Models for ballistic ejection of particles
e) Changes in size and shape of vent during eruption
f) Eruption plumes
i. Momentum-dominated (gas-thrust) lower part
ii. Buoyancy-dominated (convecting) upper part
iii. Neutrally-buoyant umbrella at the top
g) Causes of plume collapse
h) Rates of falling and cooling particles
i) Aerodynamic sorting of particles
Eruption styles
a) Volcanic Explosivity Index (VEI)
b) Walker's eruption classification
c) Hawaiian Kilauea
d) Strombolian Stromboli
e) Vulcanian Vulcano
f) Surtseyan Surtsey
g) Phreatoplinian Taupo, Campi Flegrei
h) Subplinian Mount St. Helens
i) Plinian Pinatubo, Vesuvius
j) Ultraplinian Yellowstone
Pyroclastic deposits
a) Air fall
b) Pyroclastic surge
c) Pyroclastic flow
d) Vent, proximal, and distal facies of tephra and lava
e) Pumice rafts
f) Paleontological significance of pyroclastic deposits
Volcanic landforms
a) Monogenetic versus polygenetic volcanoes
b) Frequency of eruptions from the same vent
c) Eruption durations
e) Rates of magma supply and discharge
f) Life expectancy of an unreplenished magma reservoir
g) Discharge rate versus time for eruptions
h) Flood and plains basalts
i) Shield volcanoes
j) Stratovolcanoes
k) Calderas
l) Cinder cones and scoria cones
m) Maars, tuff rings, and tuff cones
n) Littoral cones and pseudocraters
o) Submarine flows and seamounts
p) Subglacial volcanoes; the effects of snow, ice, and meltwater
q) Jointing in volcanic rocks
Case histories
a) Vesuvius 79AD
b) Taupo 186
c) Sunset Crater 1065
d) Campi Flegrei 1538
e) Laki 1783
f) Tarawera 1886
g) Heimaey 1973
h) Mount St. Helens 1980
i) Mt. Pinatubo 1991
Volcanic hazards
a) Definitions of risk, value, vulnerability, and hazard
b) Lava flows; Nyiragongo, 1977; Kilauea, 1987-90, Mauna Loa, 1984; Etna,1992; Vesuvius, 1944; Izu Oshima, 1986
c) Directed blasts: Mount St. Helens, 1980; Byezymianny, 1956
d) Slope collapse; Mount St. Helens, 1980; Bandai, Unzen, 1792; Hokkaido-Komagadake, Etna, Vesuvius, Toluca, Colima
e) Pyroclastic flows and surges; Vesuvius, 79; Pelee, 1902; Lamington, 1951; El Chichon, 1982; Unzen, 1991; Pinatubo, 1991; Merapi, 1994; Soufriere Hills, 1995-1998
f) Ballistic fragments; Arenal, 1968; El Chichon, 1982; Etna; Vulcano, 1888-1890
g) Air falls; Vesuvius, 79; Mount St. Helens, 1980; Pinatubo, 1991; Tarawera, 1886; Rabaul, 1994
h) Lahars; Ruiz, 1985; Pelee, 1902; Redoubt, 1989; Pinatubo, 1991
i) Floods (jokulhaups) from subglacial eruptions; Loki/Grimsvatn, 1996
j) Tsunamis; Krakatau, 1883; St. Augustine, Hokkaido-Komagadake
k) Suspended dust; Mount St. Helens, 1980; El Chichon, 1982; Redoubt, 1989; Spurr, 1992
l) Aerosols and acid rain; Masaya, El Chichon, Pinatubo
m) Gases: Askja 1783, Heimaey, 1973, Indonesia, Cameroon
n) Ground deformation; Krafla, Campi Flegrei, Usu, Iwo Jima, Rabaul
o) Disease and starvation; Iceland, 1783; Guatemala, 1902
Forecasting eruptions
a) Definitions of "forecast" and "prediction"
b) Need for baseline data from dormant periods
c) Changing heat flow, and fumarole and hot spring temperatures
d) Ground deformation
e) Seismicity
f) Changes in local magnetic, gravity, resistivity, and magnetotelluric fields
g) Changes in chemistry of effluent from soils, hot springs, and fumaroles
Making money from volcanoes
a) Agriculture
b) Tourism
c) Extractable resources
i) Geothermal energy
ii) Fumarole and hotspring deposits: sulfur, mercury, clays
iii) Contintental environments: Modern and fossil "epithermal" Au-Ag veins, Cu, Mo, Au, etc. in subvolcanic plutons
iv) Marine environments: modern seafloor hydrothermal systems; fossil "massive sulfide" Cu-Zn-Pb deposits
v) Building and paving stone, insulation, abrasive; welded tuff, lava, pumice
vi) Diamonds
Effects of volcanism on weather, climate, and human activity
a) Localized short-term effects; heavy rains, lightning
b) Widespread short-term effects on temperature and atmospheric chemistry; shortened growing seasons, severe winters, acid rain, depleted ozone layer;
triggering of El Nino by large-volume submarine lava eruptions? The evidence from ice cores.
c) Impact on agriculture, transportation, and communication
d) Impact on water supplies, structures, and public health
e) Widespread long-term effects of gases, aerosols, and suspended dust; the enigmas of the end-of-Permian and end-of-Cretaceous extinctions
Modifying eruptions ("pre-emptive strikes")
a) Diverting, chilling, and explosively disrupting lava flows
b) Draining crater lakes
c) Diverting and entrapping mudflows
d) Diverting and entrapping pyroclastic flows
e) Using explosives to block or enlarge events
f) Using explosives to fracture domes
g) Modifying topography to redirect blasts
h) Inducing phreatic eruptions
i) Reducing pressure in magma reservoirs by drilling, blasting, hydrofracturing, and aquifer management
Volcanology and public policy
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