VOLCANOESTHESE NOTES GO ON P. 11 OF YOUR INB!!!

VOLCANIC SETTINGS (PLATE BOUNDARIES)

CONTINENTAL divergence

Ocean-Continent

ConvergenceOcean

Divergence

Ocean-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

Lanai

Maui

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.