Introduction
Overview
This is an interactive Internet lesson in which students will explore earthquakes by reading
eyewitness accounts and viewing animations of earthquake causes and forces. Students will
also learn how to measure earthquakes and locate their centers by working with real
seismograms. As part of an ongoing process, students will apply what they learn by
monitoring daily seismic activity around the world for major earthquakes and by keeping a
journal of their magnitude and epicenter location. This lesson utilizes reading, writing, and
computational skills in an interdisciplinary format.
Subject Matter
Earth Science, Mathematics, Language Arts, Geography
Grades
High School
Curricular Uses
Scales, logarithms, amplitude, graphs, ratios, proportions, radius, compass, magnitude,
intensity, plate tectonics, faults, seismic waves, seismograms, maps.
Learning Objectives
Students will be able to:
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Describe the characteristics of an earthquake;
Understand the causes of an earthquake;
Describe the different seismic waves;
Discuss the advantages and disadvantages of the Richter and Mercalli scales;
Measure time and amplitude on a seismogram;
Calculate the magnitude of a local earthquake using a nomogram;
Calculate the epicenter distance of a local earthquake using a nomogram;
Calculate the magnitude of a global earthquake using a formula;
Calculate the epicenter distance of a global earthquake using a P and S wave traveltime graph;
Locate the epicenter of an earthquake by triangulating on a map.
Materials
(per student)
1. 1 journal folder containing loose-leaf and pockets.
2. 1 compass and metric ruler.
3. 1 outline map (http://www.eduplace.com/ss/ssmaps) of the major continents plus
California regions and the United States (a map of South America is needed for Lesson
Five).
4. 1 scientific calculator with logarithmic functions.
5. 1 P and S wave travel-time graph (a standard reference table in most Earth Science
textbooks).
6. 1 map of stations (http://aslwww.cr.usgs.gov/Stations/station_info/mainmap.htm)
operated by the USGS Albuquerque Seismological Laboratory.
(per class)
1. Atlas (one or two per class of students).
2. Computers with access to the World Wide Web (ideally, one per group of three
students).
3. Printers with graphic capability (inkjet or laser are best) and printer paper.
Computer Resources
You will need at least one multimedia computer workstation with Internet access. We
recommend, as a minimum, using Macintosh II series running System 7.0 or higher, or a 386
IBM compatible PC running Windows 3.1 or higher. We also recommend a minimum modem
speed of 14.4K bps, though 28.8K is preferable. The Internet plug-ins Shockwave and Flash
should be added to your Internet browser to view certain applications. They are available on
the Internet atMacromedia.com.
Bookmarks
(For a description of each site, go to the Resources Section.)
Bookmark the following sites:
Earthquakes: Eyewitness Accounts
http://www.zephryus.demon.co.uk/education/geog/tectonics/witness/eye.html
Earthquake Hazards
http://www.geo.mtu.edu/UPSeis/hazards.html
Before, During, and After
http://www.geo.mtu.edu/UPSeis/bda.html
Earthquakes: The Richter Scale
http://www.zephryus.demon.co.uk/education/ geog/tectonics/richt.html
Savage Earth Online
http://www.thirteen.org/savageearth
Electronic Desktop Project: Virtual Earthquake
http://vcourseware.calstatela.edu
Live Internet Seismic Server
http://aslwww.cr.usgs.gov/Seismic_Data/heli.htm
Make Your Own Seismogram!
http://quake.geo.berkeley.edu/bdsn/make_seismogram.html
PNSN Webicorder Display
http://www.geophys.washington.edu/SEIS/PNSN/WEBICORDER/welcome.html
The Java Helicorder
http://www.seismo.unr.edu/ftp/pub/ichinose/ JavaWorm/WormWavesApplet.html
USGS: Ask A Geologist
http://walrus.wr.usgs.gov/ask-a-geologist/
Build Your Own Seismograph
http://cse.ssl.berkeley.edu/lessons/indiv/davis/hs/Seismograph.html
Prerequisite
Students should have some familiarity with the Internet and how to utilize a Web browser.
LESSON ONE
Introduction: Why is this lesson constructivist?
Using interactive Internet programs and resources, this unit contains a variety of activities
that enable students to construct their understanding of the nature of earthquakes and their
impact on the earth. An authentic context is created whereby students research the causes of
earthquakes, measure their force and intensity, and maintain a log of their findings in personal
journals. Students also work in groups to collaborate on research, exchange ideas, discuss the
findings of their research, and present their findings both in the form of a written report and
orally to the class. In addition, this unit highlights the constructivist principle that content
should be taught not in isolation, but in relation to all aspects of the real world. Therefore, the
lessons integrate a diversity of skills across the curriculum: earth science for earthquakes;
mathematics for calculations and formulas; language arts for writing journals, reports, and
presentations to the class; and geography for locating earthquake activities in the world.
Each lesson begins with student discovery through a brainstorming activity that draws on
previous insights and builds on newly constructed knowledge. In the constructivist tradition,
students attempt to construct their knowledge through problem-solving. For example,
students think of ways to measure the magnitude of an earthquake and locating its epicenter.
Only then are they introduced to existing instruments that measure the force of earthquakes.
Students' ideas are then tested, confirmed, or modified according to their research. Finally,
students apply their knowledge to a real-world, ongoing activity. Students access authentic
Seismic Stations through various Internet sites in order to monitor earthquake activity,
measure the seismograms, and calculate the magnitude and triangulate the map of the
epicenter. The research and findings will be entered into the journals and reported back to the
class.
What is an earthquake? (one class period)
[For the Teacher]:
Distribute journal folders. Tell students that the folders will be used as research journals. Have
them place their names on the cover. Introduce the word earthquake. Elicit from the students
what they know about earthquakes. List their comments on the board. Break students up into
groups of three and assign each group one of five essays to read from Earthquakes:
Eyewitness Accounts(http://www.geographysite.co.uk/pages/physical/earth/witness/eye.html). Students should write the names of their
groups in their journals. Groups should write down characteristics and effects that they
consider important for an earthquake. Have groups read their reports and list items on the
board. Ask the class to compare the items they listed before with eyewitness descriptions.
Have groups go back to the Internet and access the Earthquake
Hazards(http://www.geo.mtu.edu/UPSeis/hazards.html) and Before, During, and
After(http://www.geo.mtu.edu/UPSeis/bda.html). Discuss characteristics and effects with the
class. What is liquefaction? Why is there a danger of fire? What can happen to
communications, water, and means of transportation? These are just some of the possible
items to discuss.
[For the Students]:
Write your name and the names of your group members in your journal.
Get the title of the essay your teacher wants your group to read.
If you are assigned one of the eyewitness essays go to: Earthquakes: Eyewitness
Accounts (http://www.geography-site.co.uk/pages/physical/earth/witness/eye.html).
As your group reads the essay, write down keywords or phrases that describe the earthquake
and its effects.
After giving your group report, go to the Earthquake
Hazards(http://www.geo.mtu.edu/UPSeis/hazards.html) site and take notes on the effects of
earthquakes.
Next, go to the site Before, During, and After(http://www.geo.mtu.edu/UPSeis/bda.html) and
take notes. Afterwards, your teacher will call the groups together to discuss your data.
LESSON TWO
What are the causes of earthquakes and their effects? (two class periods)
[For the Teacher]:
Distribute the journals. Remind the students to record information as they learn it. Break up
the class into groups of three again. Go to the Savage Earth Online(http://webcr05.pbs.org/wnet/savageearth/index.html) site and have students investigate Hell's Crust.
Hell's Crust will animate place tectonics. Every group is assigned to read the article and view
the animation. Also each group is assigned one of the three sidebars. After, have the class
comment on the article and animations. Next, have each group report on their assigned
sidebar.
When this is done, have the groups go back to the Internet and view Savage Earth online, The
Restless Planet. Restless Planet will animate earthquake faults and seismic waves. Every group
is assigned to read the article and view sidebar one and the animation. Each group is assigned
to view one of the two remaining sidebars. Have the class discuss the article, sidebar one and
the animation. Finally, have each group report on their assigned sidebar.
Next, have the groups go back to Savage Earth online and view Out of the Inferno: Volcanoes.
Every group is assigned the article and animation. Each group is assigned one sidebar. Have
the class discuss the article and animation, and have groups report on their assigned sidebar.
Finally, have students go back to Savage Earth online and view Waves of Destruction:
Tsunamis. Every group is assigned the article and animation. Each group is assigned one
sidebar. Have the class discuss the article and animation, and have groups report on their
assigned sidebars.
[For the Students]:
Go to Savage Earth Online (http://web-cr05.pbs.org/wnet/savageearth/index.html) and click
on Hell's Crust.
All groups will read the article and view the animation.
Remember to write entries in your journal. When finished, click on the sidebar assigned by
your teacher.
After giving your group report, go back to the Savage Earth homepage(http://webcr05.pbs.org/wnet/savageearth/index.html) when instructed by your teacher and click on The
Restless Planet. All groups will read the article, sidebar one, and the animation. When finished,
click on the sidebar assigned to your group by your teacher.
After giving your group report, go back to the Savage Earth homepage when instructed by
your teacher and click on Out of the Inferno: Volcanoes. All groups will read the article and
view the animation. When finished, click on the sidebar assigned to your group by your
teacher.
After giving your group report, go back to the Savage Earth homepage when instructed by
your teacher and Click on Waves of Destruction: Tsunamis. All groups will read the article and
view the animation. When finished, click on the sidebar assigned to your group by your
teacher.
Group reports will be given one more time.
LESSON THREE
How are earthquakes measured? (one class period)
[For the Teacher]:
Distribute the journals. Break students up into groups again. Ask them to brainstorm how they
would measure an earthquake. Have groups report their ideas. Next, have them access the
site Earthquakes: The Richter
Scale(http://www.zephryus.demon.co.uk/education/geog/tectonics/richt.html). Groups should
note how the Richter and Mercalli scales are used and the advantages and disadvantages of
each. After viewing the site, have groups report on the two scales and how they are used.
Point out that the Richter scale is a logarithmic scale and that each increase of one is a tenfold increase in energy.
Discuss logarithms and how they are used. Students should know that the natural logarithm of
10 is 1, of 100 is 2, and so on. Ask them what the log of 50 would be? The question could be
framed as follows:
10 1=10
10 2=100
10 ? = 50 (between one and two)
Show students how to get natural logarithms on a scientific calculator. After discussing
logarithms, ask groups to report on the advantages and disadvantages of each scale.
How are earthquakes measured?
[For the Students]:
Discuss with your group how you would measure an earthquake. Don't forget to write in your
journal.
After group reports, go to the Earthquakes: The Richter
Scale(http://www.zephryus.demon.co.uk/education/geog/tectonics/richt.html) site and take
notes on how the Richter and Mercalli scales are set up, and how they are used. Write a
paragraph on the advantages and disadvantages of each scale. When finished, group reports
on the Richter and Mercalli scales will be given.
Next, your teacher will give you a short lesson on logarithms. Remember that logarithms are
exponents. Natural logarithms use a base of 10. Scientific calculators have a log button that
gives the natural logarithm of positive numbers.
After the minilesson, group reports will be given on the advantages and disadvantages of both
scales.
LESSON FOUR
How do we get the magnitude and epicenter of an earthquake? (one class period)
[For the Teacher]:
Distribute the journals. Discuss seismograms and seismometers. Point out that different
seismic waves make different patterns. P waves look jittery with no pattern of peaks and
valleys; S waves make recognizable patterns of peaks and valleys. P waves are compression
waves whereas S waves are shear waves going sideways. Have examples to show them. Next,
have students access the Electronic Desktop Project: Virtual
Earthquake(http://vquake.calstatela.edu/eec/Earthquake/) site.
Groups can be together but it is better that each member of the group has his/her own
computer. The site will ask him/her to choose an earthquake location. The site will post
seismograms of a past earthquake at that location. Virtual Earthquake will teach students how
to measure earthquake travel time and wave amplitude on the seismograms. All students are
given more than one chance to get it right. The site will show students how to use seismogram
measurements to calculate magnitude using a Richter nomogram and how to triangulate three
seismograms to find the earthquake's epicenter. After completion of the exercises, students
are issued certificates of completion that can be saved as GIF images and printed later for
their journals.
How do we calculate the magnitude of an earthquake and locate its epicenter?
[For the Students]:
Your teacher will give you a short lesson on seismograms. They are produced on
seismometers, which record earthquake waves. P or primary waves are compression waves
and are seen on the seismogram as jittery peaks with no pattern of valleys. S or secondary
waves are shear waves and they record back and forth motions. They have a definite pattern
of peaks and valleys and can be quite large.
When instructed, go to the Electronic Desktop Project: Virtual
Earthquake(http://vquake.calstatela.edu) site. The site will teach you how to use a
seismogram to find the magnitude and epicenter location of a local earthquake (within 500
miles). Remember to take notes in your journal.
When you are finished, the site will give you a certificate of completion. Ask your teacher if
you can print it now or save it for printing later.
LESSON FIVE
How do we measure global earthquakes? (two class periods)
For the Teacher:
Distribute the journals. Richter nomograms are fine for local earthquakes, but what about
earthquakes from places far away? Break students into groups of three. Distribute South
American seismograms from Bolivia, Brazil, and Argentina. Have students measure
earthquake travel time on the seismograms, and the amplitude of each. If students have
difficulty locating the start of the P and S waves, tell them to look for differences in patterns,
and for patterns of peaks and valleys. To calculate an earthquake's magnitude, I have used a
modified version of Richter's nomogram formula with some success. The formula is:
The formula is not as difficult as it looks. Walk them through it once or twice. When you get
the magnitude of the three seismograms, average them to get the final magnitude.
Show students how to obtain an outline map of South America from the Outline Map site
(http://www.eduplace.com/ss/ssmaps/). Have it ready to distribute. They will use this map to
triangulate for the earthquake's epicenter. Distribute P and S wave travel-time graphs.
Students will use the seismogram time measurement to locate the epicenter's distance in
kilometers from the recording station using the chart. Convert kilometers to centimeters using
the scale provided on the outline map. If the map gives miles instead of kilometers, students
will have to first convert kilometers to miles using the proportion: 55 miles:88 kilometers = x
miles:y kilometers (from the chart), then convert miles to centimeters using the scale on the
outline map. Locate the station on the outline map by using the station map of the USGS
Albuquerque Seismological Laboratory
(http://aslwww.cr.usgs.gov/Stations/station_info/mainmap.htm). Adjust a compass to the
desired centimeters and draw a circle with the station as its center. Do the same procedure for
the other two seismograms drawing their circles on the same map. The three circles should
overlap at the epicenter's location. If they don't, have students recheck their calculations. If
intersection points are close, then average the distances of the separate intersections. The
South American earthquake happened on April 30, 1999, at 19:23:46 GMT, 31.65S and
71.45W near the coast of central Chile measuring 5.0 on the Richter scale. You can obtain
seismic information for the last thirty days from Current seismic event list
(http://www.iris.washington.edu/cgi-bin/
seismon_events.pl?date=99/04/23&lat=15.27N&lon=91.74W), and going back to 1977 from
IRIS: Welcome to WILBER (http://www.iris.edu/cgi-bin/wilberII_page2.pl). Distribute a set of
Asian seismograms and have students or groups work on finding the epicenter. Also distribute
the appropriate outline map for triangulation. Students will obtain this for themselves in the
future.
How do we measure global earthquakes?
For the Students:
Your teacher will give you three seismograms of a recent South American earthquake recorded
by USGS stations. Write the names of the USGS stations in your journal.
Measure the S-P distance and use a P and S wave travel-time graph to find the epicenter
distance for each seismogram. Record the distance next to the station in your journal. You will
need this to locate the epicenter. Obtain an outline map of South America from your teacher.
Locate the USGS stations on the USGS station map provided by your teacher. Mark these
locations on your outline map. Label each location with the USGS station name.
Locate the scale that is on the outline map. If it has kilometers, calculate the number of
kilometers represented by 2 centimeters. Set up a proportion to find the number of
centimeters represented by the epicenter distance (in kilometers) for each of the three USGS
stations. If the scale is in miles, convert your epicenter distances to miles using the proportion
55 miles:88 kilometers = x miles:y kilometers (y is the epicenter distance for each station),
then use another proportion to find the number of centimeters represented by the epicenter
distance (in miles) of each USGS station. Record this information in your journal.
Take a compass and fix the radius the number of centimeters calculated for the first station.
Go to the outline map and, using the station as the center, draw a circle. Do the same for the
other two stations using their centimeter values as the radius.
Where the three circles intersect is the epicenter of the earthquake. If the circles do not
intersect but are close, take the average difference and approximate the center. If the circles
are far apart, remeasure the seismograms and recalculate the centimeters. With practice, you
will get better.
Your teacher will give you a formula to calculate the earthquake's magnitude. You will use it
for each of the three seismograms. Here's the order of operations:
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Find the natural logarithm of the amplitude measured on the seismogram.
Divide the S-P distance by 30 and get rid of the decimal (this is what is meant by
integer).
Subtract the above quotient from 8.
Multiply the S-P distance by the above difference.
Find the natural logarithm of the above product.
Multiply the above logarithm by 3.
Add the above logarithm and the logarithm of the amplitude.
Subtract 2.92 from the above sum.
Your answer is an approximation of the magnitude of the earthquake. Repeat the process with
the other two seismograms. Average the three magnitudes to get a final answer.
Ongoing Activity (one class period, then ongoing)
For the Teachers:
Break students into groups and have them access the Live Internet Seismic Server site
(http://aslwww.cr.usgs.gov/Seismic_Data/heli.htm). Show them the stations the Albuquerque
Seismological Laboratory has in its real-time seismogram network. Every day, one group will
access the site and monitor the network for earthquake activity. Not all stations need to be
contacted. For South America, contact Brazil or Bolivia or Argentina only. Activity at one
station will surely be picked up at other South American sites that can then be contacted. The
same will be true for China, Russia, Africa, and the other continents. If activity is found,
seismograms from three separate stations must be printed. An outline map of the area must
also be printed. The group then measures the seismograms, calculates the magnitude, and
then triangulates on the map for the epicenter. When finished, the group reports back to the
class. All research should be entered in students' journal folders.
For the Students:
Groups will take turns monitoring USGS stations worldwide for major earthquakes. Go to the
Live Internet Seismic Server (http://aslwww.cr.usgs.gov/Seismic_Data/heli.htm) and click on
stations to obtain their seismograms. Note that one country per continent is sufficient to
observe seismic activity. Click on the small versions because they take less time to load. If
you find an earthquake, then click on the twenty-four-hour version and print it. Use the map
of the USGS stations provided by your teacher to find two other stations near the earthquake.
Print their seismograms too. Don't forget to record the information in your journal. Go to the
Outline Map Web site (http://www.eduplace.com/ss/maps/index.html) and print a copy of the
geographic area of the earthquake. Locate the epicenter of the earthquake and calculate its
magnitude as you did in Lesson Five. Make a report of your finding to the class.
Curriculum Extensions
Have a representative from your town's city hall speak to your class about the city's plans for
an earthquake. Have a representative from the building industry or an architect speak to your
class on how buildings can be built to withstand earthquakes. Create a Web page listing
earthquake data and perhaps other data. Build your own seismometer
(http://cse.ssl.berkeley.edu/lessons/indiv/davis/hs/Seismograph.html).