Academic journal article The Science Teacher

MAKING WAVES: Exploring the Earth with Seismology

Academic journal article The Science Teacher

MAKING WAVES: Exploring the Earth with Seismology

Article excerpt

Earth's easily seen surface features (mountains, volcanoes, and islands)--and the movement of the tectonic plates that lie below--offer hints about the processes that produced them. Inquiries in seismology, the study of earthquakes and other ground movements, can help students learn about Earth's geologic processes.

This article describes an activity that uses guided inquiry-based teaching, in which students form their own questions based on data, observations, images, and text so that they can formulate their own hypotheses. Students use classroom seismographs to detect, observe, and evaluate earthquakes and other ground motions and then create their own seismicity maps. With their own data, along with official seismicity maps, students arrive at evidence-based hypotheses about geologic processes.

Background information and activity setup

This one-hour activity requires a classroom seismograph, or, lacking that, data posted online from a nearby seismograph. (See "On the web" for link #3, which accesses the Incorporated Research Institutions for Seismology [IRIS] earthquake stations, where you can choose a seismograph station.) Alternatively, educational seismographs can be purchased online for less than $1,000. Also, seismograph and accelerometer apps can be purchased for mobile devices for a few dollars; however, these are limited in their precision and capabilities and aren't well suited to this activity.

Begin the lesson by discussing key vocabulary and earthquake concepts (e.g., earthquake; magnitude; types of faults; epicenter; seismograph; seismicity; plate tectonics; and convergent, divergent, and transform plate boundaries). Students also should identify and discuss visible features on Earth's surface (e.g., mountains, islands, bodies of water, volcanoes), using a topography map or globe. Ask students how they think these features were formed. They should conclude that these geologic features resulted from Earth's processes, a concept important to the development of the theory of plate tectonics. (For connections to the science standards, see p. 37.)

Next, introduce students to the seismograph, an instrument that records seismic waves (propagating vibrations that carry energy from the source of an earthquake outward in all directions), provides information about Earth's internal layers, and hints at what processes occur on our dynamic planet. Use the graphic shown in Figure 1 (and available via link #1 "On the web") to help explain seismic waves and how they travel through the Earth.

Have students observe the seismograph's parts, how it works, and what information it yields. Then, ask students again: "How were Earth's features formed? Were geological processes restricted to Earth's surface? Do additional tools provide more insight to explain the formation of the features we observe on Earth?" Then, distribute a copy of Figure 2 (available via link #7 "On the web") to each student.

On this map, students should highlight surface features (e.g., mountains), using the legend as a guide. A few of my students color-coded different features, whereas others simply drew circles around one specific feature. Afterward, discuss where faults and earthquakes might occur around these surface features. Students will need more information to answer this question.

Engage

In this phase, students use online seismicity maps from the United States Geological Survey (USGS; see Figure 3 and link #2 "On the web"). The site's default display settings show all U.S. earthquakes with magnitudes greater than 2.5 that occurred over the past 24 hours. Students can experiment by changing the parameter settings, such as magnitude, time period, and location. Each change yields a different but similar seismicity map. Students can use black pens to draw small circles representing earthquake epicenters on their global plate tectonics map (Figure 2, p. 33).

Viewing a seismicity map for the past 30 days of earthquake activity piqued my students' interest. …

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