Earth Shakes, Rattles, and
Rolls
Plate Tectonics
Volcanoes
Earthquakes
What is the relationship
between the earth’s
plates, volcanoes, and
earthquakes?
Plates
http://www.extremescience.com/PlateTectonicsmap.htm
Earthquakes
Volcanoes
http://hsv.com/scitech/earthsci/quake.htm
Let’s look at those
maps again.
Plates
Volcanoes
Earthquakes
Earthquakes and Volcanoes are found
where plates meet.
Evidence Wegener used to
support theory of continental
drift:
• Continents fit like a puzzle
• Fossil evidence
• Rocks were similar in Africa and
South America
• Evidence Antarctica once had a
tropical climate
How did geologists explain
how the earth’s plates
moved?
Mid-Atlantic Ridge allows mantle
to seep to surface through cracks
and pushes plates of the earth
apart.
To see how geologists believe
the plates moved go to the site
below.
Notice the Atlantic Ocean seafloor
spreading.
Seafloor spreading animation
•Crust
•Mantle
•Outer core
•Inner core
Types of Mountains
• Folded
• Fault-block
• Volcanic
• Unwarped
FOLDED MOUNTAINS
http://www.cssd11.k12.co.us/dohnts/images/earth/fldmtn.jpg
FOLDED MOUNTAINS
•Appalachian Mountains in the eastern United States,
and the Swiss Alps in Switzerland
•form when two plates collide head on, and their
edges crumble
•consist mainly of sedimentary rocks, like limestone
and shale
FAULT-BLOCK
MOUNTAINS
FAULT-BLOCK MOUNTAINS
•Consist of huge blocks of the earth's crust that
have been tilted or pushed up along a fracture line
called a fault
•Sierra in California, Arizona is an example.
• Created when a plate hits a fault and tips upside
down, creating erosion and debris, which is at the
base of the mountain.
VOLCANIC MOUNTAIN
NAMIBIA IN AFRICA
Volcanic mountains
•Formed when molten rock, or magma
deep within the earth, erupts, and
piles upon the surface
•Made of basalt and rhyolite.
•Takes place where two of the
earth's tectonic plates collide.
UNWARPED MOUNTAINS
•Black Hills in South Dakota
•form when tectonic forces lift the earth's crust into a broad
bulge or dome raising it above its surroundings
•Erosion causes peaks and valleys to form.
Convection currents in action! At left, two animal
cookies represent two of the Earth's tectonic plates.
At right, the two plates have moved apart, much like
what happens at a divergent margin. The chocolate
pudding represents the Earth's mantle. The heat
source beneath the pot created convection cells in the
chocolate pudding. Think of the cookie on the left as
South America, and the cookie on the right as Africa.
Over time they have moved apart. You'll see this
again.
http://images.google.com/imgres?imgurl=http://visearth.ucsd.edu:16080/VisE
_teach/Kimball/untitled18.jpg&imgrefurl=http://visearth.ucsd.edu:16080/VisE
_teach/Kimball/Kimball2.html&h=200&w=308&sz=35&tbnid=sEa1xg46QV
MJ:&tbnh=72&tbnw=110&start=9&prev=/images%3Fq%3DCONVECTION
%2BCURRENTS%26hl%3Den%26lr%3D%26sa%3DN
Convection currents in the
Earth's mantle are what drive
plate motions. Convection
currents are driven by the
simple fact that hot things
(such as gases and liquids)
rise while cool things fall.
Convection currents
in the magma move
the earth’s crust.
epicenter
The point on the surface of Earth that is right
above the focus of an earthquake
http://www.harcourtschool.com/glossary/science/define/gr4/epicent
er4c.html
http://uc.wisc.edu/news/features/quake/pwaves.html
Go to this site to see an
animation of the path of p
waves and s waves
http://www.pbs.org/wnet/savageearth/animations/earthquakes/
Earthquakes
How do we measure the
intensity of an earthquake?
Seismograph
measures
or the strength of an
earthquake
Seismograph records energy waves of the earth
Mercalli Scale
I.People do not feel anything .
V.
•People feel movement.
•Doors open
•Pictures fall off wall.
VII.
•Some buildings lose bricks.
•Difficulty driving.
IX.
Considerable damage to homes.
Cracks in earth.
XII.
•Almost everything is destroyed.
• The ground moves in waves or ripples.
Richter Scale
Earthquake Magnitudes
Less than 3.5
Effects
Generally not felt
3.5-5.4
Rarely causes damage.
Under 6.0
Slight damage to well-designed buildings.
6.1-6.9
Destructive to about 100 kilometers across
7.0-7.9
Major earthquake. Serious damage over larger areas.
8 or greater
Great earthquake.
Each number is 10X stronger than the
previous number.
How much stronger is the 3
than the 1? 100
Times
How much stronger
is the 8 than the 1? 10,000,000
Write the number in
scientific notation.
106
Why is the Richter Scale more
accurate than the Mercalli
Scale?
•The Richter Scale is objective and
based on mathematical measurements.
•The Mercalli scale is subjective and
based on people’s perception and
experience.
•On Mercalli scale if the area is
unihabited there is no way to measure
the magnitude of the earthquake.
Richter Magnitude
1.0 to 3.9
Number of Earthquakes
per year
900,000 +
4.0-4.9
6200
5.0-5.9
800
6.0-6.9
226
7.0-7.9
18
8.0-8.9
Less than 2
One Boy’s Experience – Eyewitness Account
http://www.olympus.net/personal/gofamily/quake/famous/1906.html
Jack London’s Eyewitness Account of San Franciso Earthquake
http://sunsite.berkeley.edu/London/Writings/Journalism/sfearthquake.html
Click on url to get complete texts
San Francisco Earthquake 1906
Alaska Earthquake 1964
Earthquakes in the ocean cause
30’ Wall of Water
Destruction
Types of Volcanos
• Composite
• Cinder Cone
• Shield
•Vesuvius, Krakatoa, Fujiyama, and Mount St. Helens
•tens of miles across and ten
thousand or more feet in height.
•have small craters in their summits
http://images.google.com/imgres?imgurl=http://www.cotf.edu/ete/images/modules/volcanoes/typesb.GIF&imgrefurl=http://www.cotf.edu/ete/modules/volcano
es/vtypesvolcan1.html&h=236&w=265&sz=14&tbnid=qZF0vXnHnOkJ:&tbnh=96&tbnw=107&start=19&prev=/images%3Fq%3Dcomposite%2Bvolcano%2
6hl%3Den%26lr%3D%26sa%3DN
•consist almost entirely of loose, grainy
cinders and almost no lava
•small volcanoes
•steep sides and usually have ahttp://images.google.com/imgres?imgurl=http://www.cotf.edu/ete/images/modules/volcanoes/t
ypesb.GIF&imgrefurl=http://www.cotf.edu/ete/modules/volcanoes/vtypesvolcan1.html&h=23
6&w=265&sz=14&tbnid=qZF0vXnHnOkJ:&tbnh=96&tbnw=107&start=19&prev=/images%
3Fq%3Dcomposite%2Bvolcano%26hl%3Den%26lr%3D%26sa%3DN
small crater on top
•hundreds of miles across and
many tens of thousands of feet
high.
•Mauna Loa
•consist almost entirely of frozen
lavas
•large craters at their summits.
http://images.google.com/imgres?imgurl=http://www.cotf.edu/ete/images/modules/volcanoes/typesb.GIF&imgrefurl=http://www.cotf.edu/ete/modules/volcanoes/vtypesv
olcan1.html&h=236&w=265&sz=14&tbnid=qZF0vXnHnOkJ:&tbnh=96&tbnw=107&start=19&prev=/images%3Fq%3Dcomposite%2Bvolcano%26hl%3Den%26lr%3
D%26sa%3DN
• largest single
mountain in the
world
•30,000 +feet
above the ocean
floor
• 100 miles
across at its
base.
Image Resources
For additional diagrams of volcanoes click
below:
http://www.enchantedlearning.com/subjects/volcano/labelvolc
ano.shtml
http://images.google.com/imgres?imgurl=http://www.cotf.edu/ete/images/modules/volcanoes/typesb.GIF&imgrefur
l=http://www.cotf.edu/ete/modules/volcanoes/vtypesvolcan1.html&h=236&w=265&sz=14&tbnid=qZF0vXnHnOk
J:&tbnh=96&tbnw=107&start=19&prev=/images%3Fq%3Dcomposite%2Bvolcano%26hl%3Den%26lr%3D%26sa
%3DN