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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.

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Volcanoes these notes go on p 11 of your inb

VolcanoesThese notes go on p. 11 of your inb!!!


Volcanic settings plate boundaries
Volcanic Settings (Plate Boundaries)

Ocean-Continent Convergence

Ocean-Ocean Convergence

CONTINENTAL divergence

Ocean Divergence



RING OF FIRE”:Area surrounding the pacific plate where the most volcanoes & earthquakes occur



Parameters of volcanism

Viscosity

Chemistry of Magma

Gases within the magma

Water content of magma

PARAMETERS OF VOLCANISM


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

Volcanic activity


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)

TERMS TO KNOW:

  • depends on the amount of silica

  • the type of crust being melted determines the amount of silica!


Terms to know1

Caldera: large crater shaped basin that forms when the top of a volcano collapses

Terms to know:



Terms to know2

Kaui

Oahu

Molokai

Lanai

Maui

Hawaii

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



3 types of volcanic cones

Cinder Cone

1. Cinder Cones: explosive eruptions, small but steep slopes, pyroclastics

3 types of volcanic cones:



3 types of volcanic cones1

2. Shield: non-explosive eruptions, fluid basaltic lava, gentle broad slopes

3 types of volcanic cones:



3 types of volcanic cones2

3. Composite Cones/Stratovolcanoes: alternating between lava and pyroclastics, explosive and non-explosive eruptions, very steep/tall

3 types of volcanic cones:




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: Pillow

    http://www.youtube.com/watch?v=DdIUuUY0L9c

C

Mid-ocean ridges & oceanic hot spots


Basaltic lava types

C

Basaltic Lava Types


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

Subduction boundaries


Pyroclastic flows

searing superheated gas and volcanic ash & dust; very fast

Also called

“NueeArdente”

C

PYROCLASTIC FLOWS

http://www.youtube.com/watch?v=-H_HZVY1tT4

Mt. St. Helens Eruption

http://www.youtube.com/watch?v=WxlRpuTed6g

Pyroclastic Flow



Continental divergent boundary continental hot spots

C Washington

Continental divergent boundary & Continental hot spots

  • 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


Basaltic Magma Washington

Rhyolitic Magma

Andesitic Magma

Silica Content

Least (~50%)

Intermediate (~60%)

Most (~70%)

Gas Content

Least

Intermediate

Most

Viscosity

Least viscous

Intermediate

Most viscous

Type of Eruption

Rarely explosive

Usually explosive

Sometimes explosive

Melting Temp.

Highest

Intermediate

Lowest

Location

Subduction boundaries

Rifts, oceanic hot spots

Continental hot spots

Magma and Erupted Materials


Volcano caricatures

Volcano CarIcAtures


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