Adopt a Seismograph Station

Students choose one of the stations in the global seismic network to monitor over a period of time (one month or longer). Using seismic data generated from earthquakes and other events that occur around the world daily, students record observations individually while the class assembles a master list of events, noting the location of earthquakes and the distribution of the seismograph stations that detect them.

Concepts and learning outcomes	Students will understand that: Earthquakes occur at locations all over the world. Most earthquakes occur near plate boundaries Earthquakes occur every day Earthquakes vary in magnitude Seismograph stations detect ground movement from earthquakes and other seismic events Seismograph stations do not detect every earthquake due to the distance to the earthquake, the earthquake’s magnitude, background noise, and other factors Non-earthquake events are often only detected by nearby seismograph stations (except for nuclear blasts) because they involve so much less energy than typical earthquakes. The Earth is a noisy place; it vibrates, shimmies, and buzzes from natural and human induced events
Appropriate for	Grades 6-9
Time requirements	One 45 minute session to learn how to navigate REV and choose a station, then 10 minute sessions daily or at periodic intervals.
Vocabulary	seismic wave seismograph seismogram
Prerequisites	Students should know what an earthquake is and what seismic waves are. They should know the names of the continents and oceans and have basic computer skills. Students should be able to find locations on a map using latitude and longitude coordinates. If students need help with this, consult the Latitude and Longitude Review Lesson. It is recommended that you (and your students) go through the Rapid Earthquake Viewer Tutorial before starting this lesson. (Alternatively, you can give them a demonstration.) Students should understand REV’s organization and how to access and read the data.
Background for teachers	The Earth’s crust is composed of plates that fit together like a jigsaw puzzle. Unlike a static puzzle, these plates are in constant motion pushing against or moving away from each other. These motions cause stress to build up along plate boundaries. The stress is relieved when the plates slip past one another rapidly. This sends out seismic waves in all directions eventually reaching the surface in what is experienced as an earthquake. By placing sensors or seismograph stations on the Earth, we can detect the seismic waves resulting from plate movements. Thousands of seismograph stations have been placed around the world creating a global network. More information about these stations can be found at the USGS Monitoring Networks site. The Rapid Earthquake Viewer tool displays earthquakes which are greater than 5.5 magnitude for worldwide earthquakes and greater than 3 for earthquakes in the United States. Smaller earthquakes are not displayed in the tool. Since many earthquakes are recorded around the globe, seismologists need to agree on a single way to identify times without confusion about different time zones ("7pm" in California is not the same as "7pm" in Uzbekistan). That's why scientists usually agree to report the time as if they all lived in the same time zone – that of Greenwich, England. In REV, the time at which an earthquake occurs is listed in GMT (Greenwich Mean Time), sometimes called Greenwich Meridian Time because it is measured from the Greenwich Meridian Line at the Royal Observatory in Greenwich, England (historically, the observatory housed a very accurate clock). You can determine how GMT relates to your local time by consulting "GMT" in the REV Glossary. Any disturbance or force acting on the earth's surface will generate seismic waves, some of which are large enough for seismographs to record. While it's easy to imagine man-made noise sources, they are much less energetic than natural sources and tend to be less constant. Below is a summary of some different noise sources: Humans produce some noise. Urban noise. Noise from traffic (like big trucks shaking your house as they drive by), construction, and other human activity cause noise detected at urban stations. These are easy to comprehend, but many of the seismograph stations included in REV are located far from urban areas where such noise is less important. A key diagnostic of urban noise is that it occurs during the daytime but gets quieter at night when people sleep. Look at a 24 hour sequence of data and see if you can see such a pattern (don't forget to convert from GMT to the time zone for that station). Mining and quarry explosions. Most regional earthquake records also keep track of these substantial but non-tectonic events. How do you recognize a quarry blast? The easiest diagnostic is that its "epicenter" is located directly on top of a known quarry or mine. Nuclear tests. The largest US nuclear test ever, a 5 Megaton explosion, produced seismic waves equivalent to a magnitude 6.9 earthquake, but seismograms of explosions don't look like earthquakes. Explosions are blasts that push uniformly outward, so they produce almost entirely compressional waves (P waves). Earthquakes occur when two blocks of crust slide past one another, which releases more of their energy in shear waves (S waves). (See illustration). Nature produces a lot of noise. Ocean waves moving across shallow seas or crashing into the shoreline are believed to cause most of the constant noise seen on seismographs around the world. Coastal waves crashing into the shoreline can be recorded by seismographs as much as 100 miles inland, but are only important for stations relatively near the coast. Larger disturbances caused by storms moving over the shallow open ocean cause seismic waves that travel across whole continents. See Watching the Weather Using a Seismogram (and this lesson's Extensions section below) for more information on the connections between natural ground vibrations and meteorology. Wind on land. While a heavy wind might shake your house, it turns out that wind does not transfer seismic energy into the ground nearly as efficiently as in water in the shallow parts of the ocean. A few stations are particularly sensitive to wind. (See example) In the course of this activity, students will probably observe such occurrences in their daily recordings. As a class you can develop a method for characterizing these non-earthquake events and postulate about their causes to maintain student interest on days when no earthquakes are detected at their stations.

Materials / Preparation

Computers with internet connections to access the Rapid Earthquake Viewer. This website is also linked from the Student Web Page.
A poster-sized world map and the USGS Global Seismographic Network map, OR you can order the free Global Seismographic Network map from IRIS.
Or if you have access to enough computers, try plotting the seismic events and earthquakes (at USGS) using Google Earth.
Student Data Worksheet (1 per student)
Class Recording Sheet (poster size)
Data and recording sheets require Microsoft Office Word or another document reading program to open and print.

Grouping

If computer access allows, have students work individually so as to include more stations in the activity.

Teacher tips

Teachers who teach more than one class may want to post the data from all the classes for even greater global coverage.

LIMITED COMPUTER ACCESS
Here are several strategies for implementing this project if you only have access to one or two computers in your classroom or lab:

Periodic Data Collection
Each day have a different student access REV and gather the current earthquake data from several selected stations and report back to the class. Keep in mind that students may need written instructions on how to gather the data so that they can work independently.
Using Handouts
Students can gather the earthquake data from home computers (if available) and bring it to class OR you can do so and make copies for your students.
Teacher Presentations
If you have a computer connected to a projector, you can access REV and have the class collect the data for each station. If there are many stations of interest you can cycle through them, accessing one or two each time.

Procedures

Distribute the Student Data Worksheet. Access the REV website and click on “Station View”. This shows the monitoring stations around the world.

Have each student pick a seismograph station, click on it, and write the code, the name, and the location (latitude and longitude) of their station on their datasheet. Each station is identified by a unique three to six character code. The two letters and/or numbers at the beginning indicate the station's network code. For example, "US.NHSC" refers to a station in New Hope, South Carolina in the United States National Seismic Network. Have students determine which network their station is part of by consulting the Network listing. Good areas to select are around the “Ring of Fire” that encircles the Pacific Ocean. Note: Once each student has chosen a station, check a few days worth of data (or see if any major earthquakes - magnitude 6 or above – have occurred) to ensure that the station is reporting data on a regular basis. Have the students mark the location of their station with a pin on the large world map or the Global Seismographic Network map.

If you would like to find and use the seismic station closest to your school, enter your zip code into the box on the bottom of the station page.

Have students return to the computers and re-access the page with information about the students’ selected station. If students have moved from this page or to re-access this page on subsequent visits you have several options:
- If students use the same machine each class period they can bookmark that station’s page
- The station can be found in a list of all stations in REV. The link is also on Student Web Page and the entries are clickable.
- The triangle corresponding to the station can be clicked on the Station View page of REV as was done initially. This will work for distinctly located stations but perhaps not for one geographically close to many others.
Ground motion is recorded continuously at each station, and this view displays the last 24 hours of ground motion for that site, displayed in 2 hour segments. The students should consult this daily record and note any seismic activity. If students have been absent or wish to retrieve data from the weekend, click on the “Previous day” button and page back until they reach the day they want.
Have students click on the box beside “Show earthquakes (if any).” The screen will refresh and they will see the number of earthquakes recorded during that period (0 or more). If any earthquakes were recorded, a colored box surrounding the event will appear in the seismogram. If you hover over this with your cursor, information on the date, time and magnitude of the earthquake is displayed. Click on this box to gather additional information about this earthquake. Have students record the location of the epicenter on their Student Data Worksheet, as well as the distance from the student’s station to the earthquake. If the students’ station is not in the list provided at the bottom, click on “add a station” in the drop-down box on the left hand side to select it from the list.
Students whose stations have recorded an earthquake should announce it to the class and add a flag to their station pin on the world map or mark it with a different colored pin. The rest of the students should check their stations for activity from that earthquake and also flag their stations on the map. The class can then see the distribution of the stations that detected the earthquake. This can lead to discussions about how far away people can feel earthquakes and how far away seismographs can detect them. Periodically you may need to "refresh" the map and remove the colored pins or flags.

On the large class recording sheet, record the earthquake(s) detected that day, listing the magnitude, epicenter, stations that detected it and their distance from the epicenter. See an example of what this recording sheet could look like.
Depending on the distribution of the stations selected, there may be days in which no earthquakes were recorded. However, other events that cause shaking of the Earth may be detected, and students will notice either short “blips” or fuzzy lines that extend for long periods of time. This provides an opportunity to develop awareness that the Earth is a “noisy” place and vibrations in the Earth can be caused by a variety of events, and can be detected by seismographs. Have students try to detect the origin of these vibrations by noting time of day, duration, and events such as a large storms, avalanches or smaller earthquakes reported in the news. A good source of information about Earth events from around the globe is Earthweek. See " Background for Teachers" above for clues to help diagnose different noise sources.

By closely monitoring stations around the world for a period of time, students should be able to “capture” a live earthquake event. This will help them understand that the Earth is dynamic and that tectonic plates are in continual motion.

Assessment

Here’s a few ideas:
The student’s worksheet that they have been filling out could be used as their assessment.
If the students are creating their own map with earthquake locations, the accuracy of the mapping could be part of the assessment.

Extension

Students can learn how earthquake epicenters are determined using seismic wave data from several different stations. The Virtual Earthquake site is a good introduction.

The article, "Watching the Weather Using a Seismograph," focuses on the connections between meteorology and seismology and suggests a possible classroom project.