Download Seismology, volcanology, and without apology, geology.

Seismology
and
Volcanology
Seismology
Seismology
• Seismology is the study of earthquakes
and their effects.
• When there is an earthquake a great deal
of energy is released.
• This energy travels in the form of waves.
Seismology
• There are two kinds of seismic waves
1. Body waves
2. Surface waves
Body waves
Body waves
• Body waves travel through the ground
and move very quickly.
• There are two kinds of body waves.
Body waves
• Body waves travel through the ground
and move very quickly.
• There are two kinds of body waves.
1. Primary waves
2. Secondary waves
Body waves
• Primary waves - also called “P waves”
• Travel at about 6 km/s (they are the fastest
seismic waves)
• Can move through both solids and liquids
• The ground compresses and stretches in the
direction they travel.
Body waves
• Secondary waves - also called “S waves”
• They travel at about 3.5 km/s (They are the
second fastest seismic waves)
• Can move through solids but not liquids
• They cause the ground to squeeze and stretch
at right angles to the wave direction.
Surface waves
Surface waves
• Love waves – also called “L waves”
• They travel more slowly than body waves but
because they travel along the surface of the
Earth they cause more damage than body
waves.
So? What good is it knowing all
that stuff about seismic waves?
Seismology
Seismology
• By analyzing seismic waves geologists can
figure out a lot about the conditions
below the surface of the Earth including
the thickness and composition of each
layer.
Volcanology
Volcanology
• There are three types of volcanoes
Volcanology
1. Composite Volcanoes
Volcanology
1. Composite Volcanoes
•
•
•
Large cone-shaped volcanoes.
The “classic” volcano image.
The cone shape results from recurring
eruptions of ash and lava which builds up
layers over time.
Volcanology
1. Composite Volcanoes
•
•
•
The magma for these volcanoes is very thick
These volcanoes can have very explosive
eruptions.
Mt. Fuji, Mt St. Helens, and Mt. Vesuvius are
composite volcanoes
Composite Volcanoes
Composite Volcanoes
Composite Volcanoes
Volcanology
2. Shield Volcanoes
Volcanology
2. Shield Volcanoes
• These volcanoes form at weak parts of the
Earth’s crust called “Hot Spots” where
lava/magma can burst through.
Volcanology
2. Shield Volcanoes
• These volcanoes form at weak parts of the
Earth’s crust called “Hot Spots” where
lava/magma can burst through.
• The lava forming these volcanoes is much
more fluid than the kind at composite
volcanoes.
Volcanology
2. Shield Volcanoes
• The result is non-explosive eruptions and not
very steep slopes. But these are the largest
volcanoes in the world.
• The Hawaiian Islands, Iceland, and the
Galapagos Islands are examples of Shield
Volcanoes.
Volcanology
2. Shield Volcanoes
• The result is non-explosive eruptions and not
very steep slopes. But these are the largest
volcanoes in the world.
• The Hawaiian Islands, Iceland, and the
Galapagos Islands are examples of Shield
Volcanoes.
• Video
Shield Volcanoes
Shield Volcanoes
Shield Volcanoes
Volcanology
3. Rift Eruptions
Volcanology
3. Rift Eruptions
• These occur where ridges are spreading
• Lava comes up through the long cracks
• These are not violent eruptions but they can
release a lot of lava
• The Columbia River Plateau is a 30 m.y. old
rift eruption where the lava is about 3 km
thick.
Rift Eruptions
Video Interlude
• Video
Volcanology
Q: What comes out of a volcano?
Volcanology
Q: What comes out of a volcano?
Volcanology
Q: What comes out of a volcano?
• Gases - water vapour, CO2, sulfur.
• Tephra - solid fragments like ash,
lapilli, blocks and bombs.
• Lava – it used to be magma, now it’s
lava.
Volcanology
Q: What comes out of a volcano that will
most likely kill you?
Volcanology
Q: What comes out of a volcano that will
most likely kill you?
A: The Pyroclastic Flow – a mixture of gas,
steam and ash, superheated to over
1000⁰C, and capable of travelling at over
300 km/h.
Volcanology
Q: What comes out of a volcano that will
most likely kill you?
A: A Lahar occurs when the volcano is
covered in snow or ice. The mud, water,
ash and debris can cover large distances
very quickly.
Volcanology
The End