Risk: (vulnerability x hazard) / mitigation
o Hazard = size, frequency, type of damage
o Vulnerability = what is impacted and value
o Mitigation = $$$ invested to reduce vulnerability or to control hazard
How do we study volcanoes?
o Study and monitor active systems
o Forensic reconstruction
What is volcanology?
o Structure where magma is erupted
o Includes erupted products
o All shapes & sizes, diverse composition, subaerial & subaqueous
What is a volcanic system?
o Source Region
Mantle (Periodotite) melting Magma (Basaltic
o Transport Region
Magma moves along cracks in the earth’s crust
Forms dikes and sills
Dike: vertical intrusion of magma
Sill: horizontal intrusion of magma
o Storage Region
Magma ponds below the earth’s surface in large chambers
Magma that freezes in crust and is not erupted = intrusive rock
o Eruption Region
Igneous rocks form
Cooled at surface: extrusive/volcanic, small crystals/fine
grained, rapid cooling
Cooled below surface: intrusive/plutonic, large crystals/course
grained, slow cooling
What is volcanic system?
List the different categories of volcanic rocks and explain the differences
between the magmas they came from. Physical Properties of Magmas
o Melt density
o Decreases: basalt rhyolite; rising temperature
o Increases: cooling, pressure
o Controls: ascent, eruption
Density and Viscosity and Volcanic Behaviour.
o Viscosity: resistance to flow
o Controls flow, deformation, eruption
o Milk = low viscosity; hot, mafic, lower silica = runny; Pahoehoe
o Honey= high viscosity; cooler, felsic, high silica = gooey; AA
Use the VEI to rank the s