Volcanoes

A Lesson Plan Written By

Tom Huettl

Lecture Outline

» Areas of Volcanism

» Types of Volcanoes

» Types of Lava

» Viscosity

Lecture Outline

» Areas of Volcanism

» Types of Volcanoes

» Types of Lava

» Viscosity

Areas of Volcanism

Sub-ducting Boundaries• Plate Sub-ducts below surface into mantle

•

Oceanic-Oceanic• Volcanoes form near boundary

•

Mid Ocean Ridges• Eruptions occur where plates are diverging

•

Cont.-Cont/ Subducting

Graphic taken from

: http://147.205.15.81/geology/work/VFT-so-far/orogeny/pl.tect.html

Oceanic-Oceanic/Suducting

Graphic taken from:

http://147.205.15.81/geology/work/VFT-so -far/orogeny/pl.tect.html

Mid Ocean Ridges

Areas of Volcanism

– Hot Spots

• Hot Spots remain stationary while plates move above

•

Hot Spots

Graphic taken from:

http://volcano.und.nodak.edu/vwdocs/vw/lessons/atg.htm

l

Types of Volcanoes

– Shield Cone• Has a low rounded profile

• Gentle slopes of 2-10 degrees

•

– Composite Volcano (Strato Volcano)• Both pyroclastic layers and lava flows

• Steep sided near summit with decreasing slope

•

Types of Volcanoes

• Cinder Cone– Pyroclastic Material (Fragmented material that has been

explosively ejected)

– Ash and debris accumulates around the vent

– Small steep sided cones

–

Shield Cone

Composite Cone/Stratovolcano

Cinder Cone

Types of Lava

• Mafic» Silica Poor (45-52%)

• Intermediate» Silica Composition (53-65%)

• Felsic» Contains more than 65% Silica

– High Viscosity

» Slow Flow

» High Silica Content

»

– Low Viscosity

» Fast Flow

» Low Silica Content

»

UMD

For More Information Visit One of The Following Links

The Web's Premiere Source For Volcanoes

U.S. Geological Survey, Volcano Hazards Program

Electronic Resources

• http://147.205.15.81/geology/work/VFT-so-far/orogeny/pl.tect.html

• http://volocano.und.nodak.edu/vwdocs/vwlessons/atg.html

• http://www.studyworksonline.com/cda/content/worksheet/0,1036,EXP950_NAV2-77_SWK953,00.html

• http://observe.ivv.nasa/earth/tectonics/Tectonics.html

• http://members.aol.com/waponi/sound.htm

• http://www.bftr.com/Pages/projects/dante.html

• http://volcanoes.usgs.gov/