Seismogram Image created by Crickett.Using the excellent Virtual Courseware - Earthquake program, students learn how to read a seismogram and use them to triangulate the epicenter of an earthquake. This ...

**Summary**

Using the excellent Virtual Courseware - Earthquake program, students learn how to read a seismogram and use them to triangulate the epicenter of an earthquake. This program leads students step by step through the entire process of measuring the epicenter and calculating the magnitude of an earthquake. There is also an assessment tool associated with the program so that you can monitor how well your students did on the review quiz at the end of the activity.

**Objectives**

Can identify p and s waves on a seismogram.

Can calculate the distance from an earthquake epicenter to a seismographic station using p and s wave time difference.

Can triangulate the location of an earthquake epicenter.

Can determine the magnitude of an earthquake.

Can find the latitude and longitude of a place.

Vocabulary

fault

earthquake

epicenter

p wave

s wave

surface wave

magnitude

Richter scale

seismograph

seismogram

latitude

longitude

Attachment | Size |
---|---|

sub_earthquake_prints.doc | 49 KB |

earthquake_prints_handout.doc | 187 KB |

**Time**

45-50 minutes

Grouping

Individual or in pairs depending on the number of computers you have.

Materials

- Computers with internet access
- Copy of the Earthquake Fingerprints handout for each student

**Setting**

Computer lab

**Teacher Background**

An earthquake has struck somewhere in California! Can you figure out where? If you learn to read a seismogram you can!

First some earthquake basics… (The following background information is provided in greater detail on the student handout.) There are faults (cracks in the Earth’s surface) that can suddenly move as pressure from the movement of the Earth’s crust builds up. This sudden movement is an earthquake.

An earthquake will generate different types of waves that travel through the earth and along its surface. Several different types of earthquake waves are triggered with every earthquake. Each wave makes particles in the soil move in different ways and travels at different speeds. For our purposes, we will focus on p waves and s waves.

P waves (primary waves) are side-to side compression waves and travel quickly through the Earth. S waves (secondary waves) are up-and-down waves and are typically more destructive. In an earthquake, s waves travel more slowly than p waves. Thus, even though p and s waves start at the same time from the epicenter of a quake, the farther they travel, the greater the delay between the p and s waves.

Earthquakes are recorded on instruments called seismographs which make recordings called seismograms. The x axis represents time while the y axis represents amplitude. The time axis can show the lag between when the p and s waves arrive and can thus be used to calculate the distance between the epicenter and the location of the seismograph. The amplitude axis reflects the strength of the shaking and can be used to calculate the magnitude of the earthquake.

The Virtual Courseware program takes students step by step through these calculations. In the “Travel Time” activity, students learn the relationship between p and s wave lag time and the distance from the epicenter. In the “Epicenter and Magnitude” activity, students use seismogram recordings to determine the epicenter and magnitude of an unknown earthquake.

**Student Prerequisites**

It is recommended that students are familiar with seismographs, seismograms, the difference between p and s waves, and reading latitude and longitude from a map before using the Virtual Courseware software. The student handout has a quick summary of this information, but 5 minutes to illustrate p and s waves with a slinky and to show students a seismogram before letting a sub take over would be helpful.

The program does provide a tutorial section that will show students a seismogram being generated and the propagation fronts of a p and s wave as they travel outward from an earthquake epicenter (the “SP Lag Time” tutorial). There is a second tutorial describing how to read latitude and longitude information (the “Latitude/Longitude” tutorial). If you don’t have time to preteach these concepts, then the tutorials can serve as a prelude to the 2 activities.

**Getting Ready**

- Reserve the computer lab.
- Register your class on the Virtual Courseware site in order for the results of your students’ review quiz to be saved.
- On the main page, click the “Assessment” button under “For Instructors”.
- Read the information under the “Information” button then register your class using the “Register” button.
- Remember the class code and your password since these are required for you to retrieve your class results later using the “Class Results” button.
- Adapt the Earthquake Fingerprints handout so that the proper class code is entered on the second page near the bottom.
- Make copies of the Earthquake Fingerprints handout.

**Lesson Plan**

- Give students the student handout and allow them read the first page. Be prepared to answer questions, especially with unknown vocabulary.
- Direct students to the Virtual Courseware - Earthquakes website (http://www.sciencecourseware.org/eec/Earthquake/).
- Optional: have students complete the tutorials before proceeding to the 2 main activities. This will take 10-20 minutes extra.
- Give students 40-45 minutes to work through the 2 activities and complete the quiz.
- When students are finished, the teacher can check each person’s certificate of completion.

**Going Further**

- Go on a field trip to the Lawrence Hall of Science and let their excellent educators teach your students all about using seismographs. Afterwards, let students explore the interactive exhibits in the Forces the Shape the Bay exhibition.
- Try any one of the activities in the Earthquake! curriculum set, created by the Center for Science Education at the University of California, Berkeley. There are lesson plans for building your own seismograph, reading seismograms, locating epicenters, and using seismic clues to understand the interior of the Earth.
- For a kinesthetic version of this activity, try Whose Fault is It? by Eric Muller of the Exploratorium Teachers’ Institute (download Whose Fault is It? from Eric’s website under Earth Science activities). Students link hands and transmit p and s waves through their bodies and use the timing delay to calculate the epicenter of the earthquake.
- Listen to an earthquake! USGS has converted seismograms to sound files. Students can use them to reinforce seismology concepts such as how distance and magnitude affect a seismogram.

**Sources**

For information about earthquakes and seismology, see:

- The Science of Earthquakes, an article by Lisa Wald on the USGS website.
- G. H. Girty of San Diego State University has a comprehensive Flash based Geology 101 course including a good section Earthquakes. It is written for a college audience and includes practice exams which can easily be adapted for middle and high school students.
- The Tech Museum of Innovation has an online exhibit on the science of earthquakes.

For an extensive list of earthquake teacher resources, check out the USGS Seismic Waves page.

**Standards**

Grade 6

Plate Tectonics and Earth's Structure

1. Plate tectonics accounts for important features of Earth's surface and major geologic events. As a basis for understanding this concept:

d. Students know that earthquakes are sudden motions along breaks in the crust called faults and that volcanoes and fissures are locations where magma reaches the surface.

g. Students know how to determine the epicenter of an earthquake and know that the effects of an earthquake on any region vary, depending on the size of the earthquake, the distance of the region from the epicenter, the local geology, and the type of construction in the region.

Investigation and Experimentation

7. Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. Students will:

c. Construct appropriate graphs from data and develop qualitative statements about the relationships between variables.