Download Lab: Plate Tectonic and Earthquake Extravaganza

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Lab: Plate Tectonic and Earthquake
Extravaganza
Background:
Now that we have learned about the earths different regions (biomes) we need to
look at the stuff underneath the surface of the earth and the reason to land masses or
continents are in their current homes. We will also examine how volcanoes erupt, why
they erupt and what things form when the do so.
According to the new, generally accepted plate-tectonics theory, scientists believe
that the Earth's surface is broken into a number of shifting slabs or plates, which average
about 30 km in thickness. These plates move relative to one another at average speeds of
a few inches per year -- about as fast as human fingernails grow. Scientists recognize
three common types of boundaries between these moving plates:
1. Divergent or spreading -- adjacent plates pull apart, such as at the MidAtlantic Ridge, which separates the North and South American Plates
from the Eurasian and African Plates. This pulling apart causes "sea-floor
spreading" as new material is added to the oceanic plates.
2. Convergent -- plates moving in opposite directions meet and one is
dragged down (or subducted) beneath the other. Convergent plate
boundaries are also called subduction zones and are typified by the
Aleutian Trench, where the Pacific Plate is being subducted under the
North American Plate.
3. Transform fault -- one plate slides horizontally past another. The best
known example is the earthquake-prone San Andreas fault zone of
California, which marks the boundary between the Pacific and North
American Plates.
This motion is a very slow process and the upper portion of the earth is not
especially capable of moving in slow continuous motion, so the movement of the plates is
done in jerky motions that result in earthquakes. As these pieces of crust slide past one
another they create waves that shake the ground. Large amount of energy are required to
shake the earth and that energy is released from one point in the earth called the hypo
center. The point directly above this on the surface is called the epicenter.
Most of the world's active volcanoes are located along or near the boundaries
between shifting plates and are called "plate-boundary" volcanoes. However, some active
volcanoes are not associated with plate boundaries, and many of these so-called "intraplate" volcanoes form roughly linear chains in the interior of some oceanic plates.
The Hawaiian Islands provide perhaps the best example of an "intra-plate"
volcanic chain, developed by the northwest-moving Pacific Plate passing over an inferred
"hot spot" that initiates the magma-generation and volcano-formation process. The
peripheral areas of the Pacific Ocean Basin, containing the boundaries of several plates
are dotted by many active volcanoes that form the so-called "Ring of Fire".
Part 1: Formation of our Continents
With the idea that the plates of the earth are constantly in motion we must realize
that this means that over the life of the earth (billions of years) that the plates have been
able to move very far distances. Using fancy machinery and other scientific tools we have
been able to recreate fairly accurately the movement of these plates throughout time. Go
to the following website http://www.ucmp.berkeley.edu/geology/tectonics.html and
answer the questions below to help guide your investigation of the plates (yes answer all
questions).
First click on the history link and read the section on the topic.
1. What geographical similarity did Wegener observe that led to the notion that
some land masses may have been joined at one time?
2. What name did he give to the entire single land mass that he thought must have
existed in the distant past?
3. When did Pangaea begin to break up?
4. Why did scientists think there was a “land bridge” between Africa and Brazil?
5. What other two pairs of places showed similar fossils?
6. How were glaciers helpful in supporting the idea that continents used to be
joined?
7. What is the scientific name for mountain formation?
8. How did Wegener suggest the Himalayas formed?
9. Name two explanations that Wegener used for continental drift that were rejected
by the scientific community.
10. Who is credited with the “thermal convection” explanation for continental drift?
Go back to the main page and scroll down to the Plate Tectonics animation links.
Click on the first link: “This animation of the last 750 million years is ….
Let the animation run through entirely (5 seconds) while you view it. Use the
“refresh” button on the browser to see it again and the “stop” button to stop it at any
point to see what the continents looked like at a certain time in geological history.
Try and stop the animation at 250 million years ago and examine what Pangaea
looked like.
From the picture see if you can identify where the following continents are: (You may
have to run the animation through a couple of times to follow the movements.) * This
is not a question but you need to be able to pick them out to do the next part.
a. North America
e. Antarctica
b. South America
f. Eurasia
c. Africa
g. India
d. Australia
Go back to the main page and scroll down until you come to The Paleomap project.
Click on this link. Now click on the Earth History link. This will give you a list of
all the “Geological Eras” in our existence. Click on “Permian.”
1. Identify the continents that were all massed together.
2. Where are the Scandinavian countries (Norway, Sweden, Finland) located?
3. Where is Greenland?
Now go the Cretaceous (94 Million Years Ago)
4. Describe the conditions in Florida.
5. Where is India?
6. Where is Australia?
Now go to the K/T Extinction.
7. What happened at the Bull’s Eye marked on the map?
8. When did this event happen?
9. What is happening to India?
Now go to the Eocene (50.2 mya)
10. Where is India now?
11. Describe the conditions in Florida now.
12. What has become of Australia?
Now go to Miocene (14 mya)
13. Where is India now?
14. What will form as a result of this continental plate hitting the continental plate of
Asia?
Now go the Future World (50 million years in the future)
15. What will happen to Africa?
16. As a result of Africa moving, what will happen to the Mediterranean Sea?
17. What will eventually happen to Australia?
18. What will happen to California?
19. What will happen to the size of the Atlantic Ocean?
Now go back to the Paleomap project page and scroll down and find
“Animations.” Click on “Pangeae.” Give the map a chance to download and
then use your mouse to move the continents. This allows you to see what the
Earth was like 200 million years ago right up to the present.
20. How long does it take Indian to detach from Pangaea and strike southern Asia?
21. How long does it take for Africa and South America to just begin to separate?
22. Where did Cuba start out?
23. What was the Mediterranean Sea originally?
Part 2: Earthquake Watch
Earthquakes are important because they are used to determine the inner structure
of the Earth. They are the main reason we now know that there are layers inside of the
Earth. Earthquakes are also important because the violent motions of the earth associated
with them are not typical strains on constructed buildings. Unless structures are
constructed especially for the violent shaking, they can collapse during an earthquake.
The two main aspects of an earthquake that most scientists are interested in are its
location and the amount of energy is releases. The following two activities will help you
examine these aspects.
Since recognizing patterns is the first step in scientific discovery we will need
to plot earthquakes from prior periods of time. On the first map provided, plot
at least 50 historically significant earthquakes according to magnitude. Do not
plot an earthquake less then 5.5 in magnitude. Use one color to plot
earthquakes with magnitude 5.5 -6.9, another for those with magnitude 7.0-7.9
and a final color for any earthquake above 8.0.
A fantastic place to find earthquake data is. http://earthquake.usgs.gov
More importantly here:
http://earthquake.usgs.gov/earthquakes/world/world_deaths.php
Once you have finished answer the following questions:
1. What pattern do you recognize in earthquakes? Are there any oddities?
2. Is the length of observation great enough to identify possible cycles of
activity?
3. Does there seem to be any correlation between earthquakes and coastal
mountain systems, or active volcanoes?
4. Why is a discovery of these patterns important?
Part 3: Earthquake Measurement
You will now participate in a virtual earthquake activity to determine how
scientists determine the epicenter and magnitude of an earthquake as it is happening. The
site for the virtual earthquake lab is http://www.sciencecourseware.com/eec/Earthquake/.
If you look on the right of the page you will see a variety of tabs you will need to
do both the “Travel Time” activity and the “Epicenter and magnitude” activity from the
right. Once inside each activity read the background from the background tab and then
look at the assessment tab and follow the directions laid out for you there.
For activity one hand in your graph and your journal
For activity two you need to print your certificate of completion which you will
receive once you have finished
Part 4: Speed of Crustal Movement
We will know determine the exact velocity in which the plates of the earth are
moving. Take a handout from the front table labeled “Determining How Fast Some
Crustal Plates Move” and complete answering all questions.
Discussion: (Based on all of today’s findings)
Based on knowledge gained from today’s lab give a discussion about the
relationship between crustal plates, earthquakes, and volcanoes. This is should include
how they are related, what we can learn from them, why their history is important and
why there overall understanding is important to our lives and the environment.
A Few Questions to consider while discussing:
- Why knowledge of the history of crustal plates is important?
- Why there current study is of great importance?
- How plates are related to earthquakes and the formation of mountains
and trenches?
- How we are able to predict the presence of volcanoes and why we can
determine if a volcano is active or not?
- What is the ring of fire and why does it exist?
Note: This lab has four parts and a discussion. Each aspect will be worth 20 points, for a
total of 100 points.