Volcanoes These notes go on p. 11 of your inb !!!
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Transcript of Volcanoes These notes go on p. 11 of your inb !!!
VOLCANOESTHESE NOTES GO ON P. 11 OF YOUR INB!!!
VOLCANIC SETTINGS (PLATE BOUNDARIES)CONTINENTAL
divergence
Ocean-Continent
ConvergenceOcean
DivergenceOcean-Ocean Convergence
Major Volcanoes Around the World
“RING OF FIRE”:Area surrounding the pacific plate where the most volcanoes &
earthquakes occur
PLATE TECTONICS AND MAGMA GENERATION
PARAMETERS OF VOLCANISM Viscosity Chemistry of Magma Gases within the magma Water content of magma
VOLCANIC ACTIVITY Active Volcanoes: recent eruptions,
active magma source Mt. Etna, Italy
Dormant Volcanoes: no recent eruptions, but still has an active source of magma Mt. St. Helens, USA
Extinct Volcanoes: no recent eruptions, no source of magma Northwestern Hawaiian Islands
TERMS TO KNOW: Viscosity- the resistance of lava to flow
• Ex: The more viscous the lava, the thicker and stickier the material & the harder it is to flow (honey vs. water)
• depends on the amount of silica
•the type of crust being melted determines the amount of silica!
TERMS TO KNOW: Caldera: large crater shaped basin that forms
when the top of a volcano collapses
FORMATION OF CRATER LAKE
TERMS TO KNOW: Hot Spot- random
upwelling of magma NOT associated with convection in the mantle create a special type of
volcanism not associated with plate boundaries
Ex: Hawaii, Yellowstone & Iceland
Kaui
Molokai
Hawaii
Oahu
LanaiMaui
TECTONIC SETTINGS AND VOLCANIC ACTIVITY
3 TYPES OF VOLCANIC CONES:1. Cinder Cones: explosive eruptions, small but steep slopes, pyroclastics
Cinder Cone
VOLCANO TYPES
3 TYPES OF VOLCANIC CONES:2. Shield: non-explosive eruptions, fluid basaltic lava, gentle broad slopes
Volcano Types
3 TYPES OF VOLCANIC CONES:3. Composite Cones/Stratovolcanoes: alternating between lava and pyroclastics, explosive and non-explosive eruptions, very steep/tall
VOLCANO TYPES
Volcanism at different plate boundaries
MID-OCEAN RIDGES & OCEANIC HOT SPOTS
Effusive Eruption (non-violent): low viscosity, flows easily, gases escape easily
Magma Type: mafic (dark, dense seafloor)
Volcano Type: Shield Volcanoes
Lava Type: Pillowhttp://www.youtube.com/watch?v=DdIUuUY0L9c
C
BASALTIC LAVA TYPES Pillow Basalts (underwater)http://www.youtube.com/watch?v=DdIUuUY0L9c
AA lava- jagged lava
Pahoehoe- ropey, smooth lava
C
SUBDUCTION BOUNDARIES Mostly Explosive Eruption (violent): high
viscosity, does not flow easily, gases trapped, hard to predict explosions
Magma Type: felsic & mafic
Volcano Type: Composite Cone (Stratovolcanoes) & cinder cones
Other Features: gas flows, calderas, aerial bombs
C
PYROCLASTIC FLOWS
searing superheated gas and volcanic ash & dust; very fast
Also called “Nuee Ardente”
http://www.youtube.com/watch?v=-H_HZVY1tT4Mt. St. Helens Eruption
http://www.youtube.com/watch?v=WxlRpuTed6gPyroclastic Flow
C
DEBRIS AVALANCHE AND ERUPTION OF MOUNT ST. HELENS, WASHINGTON
CONTINENTAL DIVERGENT BOUNDARY & CONTINENTAL HOT SPOTS
C Explosive Eruption (violent): high viscosity, does
not flow easily, gases trapped, hard to predict explosions (always explosive!)
Magma Type: felsic or rhyolitic
Volcano Type: Composite Cone (Stratovolcanoes), cinder cones, dome complexes
Other Features: gas flows, calderas, aerial bombs, pyroclastic flows
Silica Content
Melting Temp.
Gas Content
Viscosity
Type of Eruption
Location
Least (~50%)
Basaltic Magma
Least
Least viscous
Rarely explosive
Highest
Rifts, oceanic hot spots
Andesitic Magma
Intermediate (~60%)
Intermediate
Intermediate
Sometimes explosive
Intermediate
Subduction boundaries
Rhyolitic Magma
Most (~70%)
Most
Most viscous
Usually explosive
Lowest
Continental hot spots
Magma and Erupted Materials
VOLCANO CARICATURES Draw an exaggerated, cartoon form of a
type of volcano Cinder Shield (Dome) Composite
Write a 5-6 sentence summary about it’s “personality.”Must include type of eruption, type of lava,
size/shape, and location.