volcanoes these notes go on p. 11 of your inb !!!
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Volcanoes These notes go on p. 11 of your inb !!!. Volcanic Settings (Plate Boundaries). Ocean-Continent Convergence. Ocean-Ocean Convergence. CONTINENTAL divergence. Ocean Divergence. Major Volcanoes Around the World. - PowerPoint PPT PresentationTRANSCRIPT
VOLCANIC SETTINGS (PLATE BOUNDARIES)
CONTINENTAL divergence
Ocean-Continent
ConvergenceOcean
Divergence
Ocean-Ocean Convergence
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:
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
Lanai
Maui
3 TYPES OF VOLCANIC CONES:
1. Cinder Cones: explosive eruptions, small but steep slopes, pyroclastics
Cinder Cone
3 TYPES OF VOLCANIC CONES:
2. Shield: non-explosive eruptions, fluid basaltic lava, gentle broad slopes
3 TYPES OF VOLCANIC CONES:
3. Composite Cones/Stratovolcanoes: alternating between lava and pyroclastics, explosive and non-explosive eruptions, very steep/tall
TYPE OF ERUPTIONS
Depends on type of crust melted Oceanic Crust- quiet, effusive eruptions
Volcano type- shield, fissure, mid-ocean ridges
Magma type- mafic & ultramafic Continental Crust or ocean/cont.
mixed- explosive eruptions, pyroclastic flows, calderas, aerial bombs Volcano type- stratovolcanoes & cinder cones Magma type- felsic
BASALTIC LAVA TYPES
Pillow Basalts (underwater)http://www.youtube.com/watch?v=DdIUuUY0L9c
AA lava- jagged lava
Pahoehoe- ropey, smooth lava
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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
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