week 2 hssp summer 2007. what is a volcano?
TRANSCRIPT
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