Download Unit: Dynamic Earth - Science Teacher Tom

Unit: Dynamic Earth
Lesson #6 – (Worksheet)
Topic: Earthquakes
Do Now: Draw diagrams representing the movement along the 3 types of plate boundaries along
with the associated features seen on Earth’s crust. Make sure to include continental-continental,
oceanic-oceanic, and continental-oceanic interactions for all 3 types of plate boundaries.
AIM: What are the causes and effects of Earthquakes and how can we locate them?
NYC Standards: S3a. Demonstrates an understanding of energy in the Earth System.
S6a. Uses technology and tools to observe and measure objects, organisms, and phenomena,
directly, indirectly, and remotely, with appropriate consideration of accuracy and precision.
Behavioral or Performance Objectives: 1. Learner will demonstrate comprehension of how
earthquakes occur by explaining the forces at work within the earth using models and diagrams.
2. Learner will demonstrate application of P and S wave dynamics by interpreting seismographic
data to triangulate the location of a hypothetical earthquake using worksheets.
Vocabulary:
1. Elastic Rebound Theory – a theory which states that continuing stress along a fault results in
buildup of elastic energy in the rocks, which is abruptly released when an earthquake occurs.
2. Focus – The location where rupture commences and an earthquakes energy is first released.
3. Epicenter – The point on the Earth’s surface directly above an earthquakes focus.
4. Body wave – a seismic wave that travels through earths interior.
a. Compressional wave – A seismic wave consisting of alternating pulses of compression and
expansion in the direction of wave travel. Travels thru solids liquids and gas (aka P-wave or
primary wave)
b. Shear wave – a seismic body wave in which rock is subjected to side to side or up and
down forces, perpendicular to the wave’s direction of travel. Only travels thru solids. (aka Swave or secondary wave)
Material List: Internet, Powerpoint, Google Earth, Compasses, Rulers, Worksheet:
http://www.scieds.com/spinet/pdf/triangulation.pdf
Safety and Disposal: No safety or disposal precautions.
Motivation: Have students watch this video and pretend as if they were in an earthquake.
http://www.sciencekids.co.nz/videos/earth/bigearthquake.html
Procedure or Development of Lesson:
Do Now: (3 minutes)
Motivation – (2 Minutes)
Section 1 – Vocab(10 minutes)
 Define and Discuss: Basic Concepts - Earthquakes, Elastic Rebound Theory, and relation
to Plate Tectonics (Video illustration of elastic rebound theory)
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http://earthquake.usgs.gov/learn/animations/animation.php?flash_title=Elastic+Rebound
&flash_file=elasticrebound&flash_width=300&flash_height=350
Based on the definition of earthquakes and using the elastic rebound theory, along what
plate boundaries would you except most earthquakes to occur? Why?
Define and Discuss: Anatomy of an Earthquake – Epicenter and Focus
By looking at this diagram, can someone point out the epicenter and focus of this cross
section of an earthquake?
Section 2 – Vocab and Earthquake Stats (13 minutes)
 Define and Discuss: Phenomena associated with an Earthquake – Body waves (P and S
waves), surface waves, energy released, earthquake stats, earthquakes measuring scales
and apparatuses.
(Video illustration of a hundred ton TNT explosion illustrating the power and energy released
from an earthquake)
http://www.youtube.com/watch?v=NHuOb3_WbfI&playnext=1&list=PL489DBB1A8046B21A
 Demonstration of P and S waves using a slinky with a student volunteer. I would have
the student first lead the demonstration. I would expect them to push one end of the
slinky horizontally towards me to show compressional waves (P waves) and also move
the slinky vertically to show shear waves (S waves).
 Knowing that the outer core of the Earth is liquid, which type of seismic wave travels
through all of Earth’s layers and which is absorbed by the inner core?
 Based on your knowledge of realistic plate boundaries and geography of the United
States, where would you expect to find a majority of earthquakes in the U.S.?
 By looking at this seismogram and your knowledge of wave characteristics, which line
represents the first detection of a P wave at this particular seismic station?
(Before moving onto the activity I will show the students a Google Earth illustration showing
earthquake epicenter locations with in the last hour, day, and week. I would go to various
locations looking at their recent earthquake history. This should make connections with the
discussed material.)
Section 3 – Activity (12 minutes)
 Students will identify the location of the P and S waves on the seismogram and from that
calculate the distance from the epicenter of the earthquake. Then using that distance
draw a circle with a radius of the calculated distance around that seismogram station.
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Section 4 – Review (5 Minutes)
 I will go over the procedure and have students present their results.
Homework: Using your knowledge of earthquakes, create and describe your own city that
would be safest from earthquakes. Be sure to mention building structure, ground type, location,
and infrastructure.
Summary and Evaluation: (5 minutes)
1. Where do most earthquakes occur?
2. What are the differences between P and S waves?
3. Can someone describe the elastic rebound theory in their own words?
4. Why is data from two seismograph stations not sufficient to calculate the epicenter of an
earthquake?
5. How do scientists know that our outer core is liquid? What evidence can they provide to
prove this?