Week 2 HSSP Summer 2007. What is a volcano?

Week 2

HSSP

Summer 2007

What is a volcano?

http://interactive2.usgs.gov/learningweb/textonly/teachers/volcanoes.htm

Why do volcanoes

erupt?

http://laurier.vsb.bc.ca/StudentP/RosaViv/Redoubt2.jpg

Why volcanoes erupt:

Magma has H2O and CO2 gases dissolved in it.

These gases form bubbles as the magma rises to the surface and make it erupt

Like a opening soda!

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

http://vulcan.wr.usgs.gov/Outreach/Publications/GIP19/

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

May 1980 Mt. St. Helens eruption

• http://video.google.com/videoplay?docid=3977416382972126736&q=Mt.+St.+Helens+1980+eruption+movie&total=17&start=0&num=10&so=0&type=search&plindex=0

http://vulcan.wr.usgs.gov/Volcanoes/MSH/Images/before_after.html

May 1980 Mt. St. Helens eruption

http://vulcan.wr.usgs.gov/Volcanoes/MSH/Images/before_after.html

May 1980 Mt. St. Helens eruption

http://vulcan.wr.usgs.gov/Volcanoes/MSH/Images/before_after.html

Mt. St. Helens today

http://vulcan.wr.usgs.gov/Volcanoes/MSH/Images/before_after.html

Mt. St. Helens today

http://vulcan.wr.usgs.gov/Volcanoes/MSH/Images/MSH04/movies_and_animations.html

QuickTime™ and aCinepak decompressor

are needed to see this picture.

What comes out of a volcano?

What comes out of a volcano?

Lava!Lava!

Lots of different kinds:

1. Ropy lava - Hawaiians call it pahoehoe

http://www.nps.gov/archive/havo/images/lava_20050628_janet_lg.jpg

What comes out of a volcano?

Lava!Lava!

Lots of different kinds:

1. Ropy lava - Hawaiians call it pahoehoe

2. Sharp lava - Hawaiians call it ‘a’a

http://volcanoes.usgs.gov/Imgs/Jpg/Kilauea/30212265-054_large.jpg

What comes out of a volcano?

Eruptive cloud:

• gases - •water vapor•carbon dioxide•nitrogen•sulfur dioxide

• ash - tiny bubbles of magma that freeze when they erupt

What comes out of a volcano?

Pyroclastic Flows = hot gas & ash from plume that quickly become heavier than air

http://www.calstatela.edu/faculty/acolvil/volcanos/pinatubo_flow.jpg

Yikes!

What comes out of a volcano?

Lahars = mud flow (pyroclastic flow + water = mud)

http://vulcan.wr.usgs.gov/Outreach/AboutVolcanoes/

What comes out of a volcano?

Volcanic Bombs = lava that cools in the air and becomes aerodynamic (like a football)

http://www.indiana.edu/~g103/G103/wk3/bomb.jpg

What comes out of a volcano?

Lots of different products!

http://www.science-art.com/gallery/98/98_182007234045.jpg

volcanicbombs

pyroclastic flows

lahars

gas & ash

How is magma formed?

Melting by heating

Decompression melting

Melting due to change in the Solidus

Why do these two eruptions look different?

http://www.windows.ucar.edu/earth/images/shield_volcano_1.gifhttp://www.volcanodiscovery.com/volcano-tours/typo3temp/pics.jpg

Stratovolcano:More ash, less lavaCone shape volcano

Shield Volcano:More lava, less ashVolcano isn’t cone shaped

http://www.windows.ucar.edu/earth/images/shield_volcano_1.gifhttp://www.volcanodiscovery.com/volcano-tours/typo3temp/pics.jpg

Because they erupt magma of different:

1) volume 2) viscosity

3) volatile-content (gas)

the 3 “V”s

What do these mean?1) volume

2) viscosity 3) volatile-content

the 3 “V”s

Volume

Stratovolcano Shield Volcano

What do these mean?1) volume

2) viscosity 3) volatile-content

the 3 “V”s

Viscosity:A measure of how much a fluid resists flowing

HIGH VISCOSITYResists Flowing,Thick, Moves Slowly honey

LOW VISCOSITYFlows Easily,Thin, Moves Quickly water

Magma is a liquid made up of different chemical species:

SiO2, MgO, FeO, Al2O3, CaO, K2O etc.

The amount of each of these chemical species affects the how easily the magma flows

More SiO2 harder to flow (more viscous)

What do these mean?1) chemical composition 2) viscosity 3) volatile-content

the 3 “V”s

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

http://vulcan.wr.usgs.gov/Outreach/Publications/GIP19/

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Low SiO2, Low viscosity,

Low volatile-content

SMALL ERUPTION

Shield Volcanoes - example Hawaii

High SiO2, High viscosity,

High volatile-content

BIG EXPLOSIVE ERUPTION!

Stratovolcanoes - example Mt. St. Helens

Stratovolcanoes vs. Sheild Volcanoes

• http://dsc.discovery.com/convergence/pompeii/interactive/interactive.html

There are volcanoes underwater

• At Mid-ocean ridges

And there are volcanoes on other planets

http://www.aerospaceweb.org/question/astronomy/solar-system/solar-system.jpg

Volcanoes in our solar system

MarsMars

http://www.lukew.com/marsgeo/img/volcanic_image2_bg.jpg

Insert movie:http://veimages.gsfc.nasa.gov/13676/VolcanoCompare_640x480.mpg

http://www.astro.virginia.edu/class/skrutskie/images/mars_volcano_size_comp.jpg

http://volcano.und.edu/vwdocs/planet_volcano/mars/Shields/olymp.jpg

http://www.visitandlearn.co.uk/factfiles06/images/volcanoes-14.jpg

http://volcano.und.edu/vwdocs/planet_volcano/venus/Ven_Ref_all.gif

VenusVenus

The MoonThe Moon

Most volcanic planet – over One Thousand volcanoes!!

Over 1600 large shield volcanoes!!

• Io is the most volcanic body in the solar system• Can be completely resurfaces in 1 million years!!• Doesn’t have craters

http://apod.nasa.gov/apod/image/0212/iovolcano_gal_big.gif

Io – moon of JupiterIo – moon of Jupiter

Can you think of some famous volcanoes?

http://www.mapsofworld.com/major-volcanoes.htm

Group Exercise

• Each group is given an information packet about a famous planet

• Your goal is to fill the “Volcano Profile” sheet

• In the end, each group will tell the class about their volcano

Volcanoes around the world

http://www.mapsofworld.com/major-volcanoes.htm

Next weekLearn to identify the rocks in your backyard!

Homework: Bring in a rock

• Any rock you like

• It can be from anywhere– Your backyard– A trip you went on– Someone gave it to you

Andesite vs. Basalt

• Andesite - – from stratocone volcanoes (explosive)– more silica– more viscous (resists flow)– pinkish or reddish in color

• Basalt - – from shield volcanoes (not explosive)– less silica– less viscous– blackish in color