Transcript Slide 1

1) TYPES OF VOLCANOES
2) WHAT IS MAGMA MADE
OF?
Composition
(What something is made of)

Determined by the where it is formed
 “geologic
setting”
 Determines


what it is made from
Mixture of SiO2, Fe, Mg and other elements.
Amount of SiO2 in the magma determines:
 Type
 Viscosity
 Gas
release ability
Why is it called lava???
I thought it was
magma…
Lava
Mafic-Dark
Intermediate
Felsic-Light
Rock Type
Basalt
Andesite
Rhyolite
SiO2%
45-50
50-60
60+
Viscosity
Low
Medium
High
Temperature
Lower-700 C
Medium
Higher-1600 C
What kind of rocks form?
Shield Volcanoes



Broader
Not explosive
Constant gas release
 Why
do you think it is not
explosive (hmm)?

High Viscosity
 Flows
really well so you
get broad short volcano
Cinder Cones




Steep
More explosive
Gases trapped
Viscosity
 What
do you think…
 Higher
Shield?
or lower than
Stratovolcanoes






Steepest
large and explosive
Symmetric
Gases trapped
Tallest
At subduction zones
Mt. Fuji, Japan
 Mt. Pinatubo, Philippines
 Mt. Rainier, Washington


Viscosity?
Guess What?!
Attention Check Time
1) If you want to make yourself a Hawaiian Shield Volcano at
home what would be a good substitute for the viscosity of
magma that it has?
A) Syrup
B) Water
C) Molasses
D) there shouldn’t be any magma
2) Which volcanoes are the most explosive?
3) Why are they so explosive (what are 2 things they have in
common)?
4) Can you think of a way to make a volcano more explosive?