Hands-on Activity Engineering to Prevent Natural Disasters:
Save Our City!

Learning Objectives

After this activity, students should be able to:

• Describe several methods that engineers use to predict, minimize or eliminate the effects of natural hazards.
• Explain that the placement of these devices is important to their effectiveness.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS: Next Generation Science Standards - Science

International Technology and Engineering Educators Association - Technology

State Standards

Materials List

Each student needs:

• Map of Unawaria
• Save Our City! Worksheet
• a set of six natural disaster prevention devices, as cut out of the attached Natural Disaster Prevention Devices Sheet (20 sets on one sheet)
• scissors
• white glue or a glue stick
• (optional) crayons

Worksheets and Attachments

Introduction/Motivation

A natural hazard is a natural event that has the possibility to cause damage. A natural disaster is a natural hazard that affects human populations. Who can tell us an example of a natural hazard? Let's make a list. (Possible answers: Volcano, earthquake, tsunami, flood, hurricane, tornado, avalanche, forest fire, thunderstorm and landslide.) Do you know of any ways that engineers keep natural hazards from becoming disasters for people, or minimize the effects of natural hazards? Engineers design many different devices. Today we are going to talk about avalanche mortars, tsunami buoys, seismometers, Doppler radar, volcano tiltmeters and water gauges. (Write these on the classroom board.)

Avalanche mortars are designed by engineers to prevent natural disasters by triggering small avalanches before enough snow builds up to cause a catastrophic avalanche. An avalanche mortar is an explosive projectile that is launched at a slope where an avalanche is likely to occur. The explosion shakes the snow loose from the slope, causing a small avalanche. (Figure 1 shows an avalauncher, which is used to launch an avalanche mortar. The typical launch method is compressed nitrogen.) Explosives can also be dropped by skiers. The advantage of the avalanche mortar is that it can easily cover a large area and is safer for ski patrollers so they do not have to ski into dangerous avalanche zones to place explosives. The problem with avalanche mortars is that they are susceptible to wind and a dud mortar leaves a live explosive on the mountain. Without the avalanche mortar, snow levels could build to a point at which a huge avalanche could cause casualties and damage structures.

Because tsunamis often start far out in the ocean, it can take hours for the huge wave to reach land. Engineers design special buoys (floating devices) that can be left far out to sea to detect tsunami waves early, allowing time for coastal areas to be evacuated. As a tsunami moves across deep ocean water, its wave is usually only a few centimeters high. Sensors placed on the ocean bottom can detect even small tsunamis. The sensor information is sent to a buoy on the ocean surface and then relayed to tsunami centers via satellite. This system is known as DART (deep-ocean assessment and reporting of tsunamis; see Figure 2). Tsunami buoys are typically placed far away from the coast so that when they detect a tsunami the maximum amount of time is made available to warn coastal residents.

The most common way of detecting and measuring earthquakes is a seismometer (also known as a seismograph). A seismometer is any device used to detect vibration in the Earth's surface. A simple seismometer consists of a something suspended from springs that are allowed to swing as the Earth shakes. A pen attached the device records all vibrations (see Figure 3). Seismometers can be sensitive enough to detect earthquakes that people cannot even feel. Seismometers can detect a powerful earthquake anywhere in the world, but often seismometers are placed near fault lines to detect very small earthquakes. This information can help engineers predict when a large earthquake is due to occur. Faults are the boundaries between the tectonic plates that make up the surface of the Earth's crust. As the plates slide along each other, they slip and grind, causing earthquakes.

Thunderstorms can form quickly and are not always easy to predict. So this is why engineers create Doppler radar stations that are able to detect approaching thunderstorms. Doppler radar works by sending out pulses or radio waves, then measuring how long it takes the waves to bounce off objects and return. In the case of thunderstorms, the radio waves bounce off the rain or hail. Information from the radar station can determine the size of a storm, how fast it is moving, which direction it is moving, and whether or not there is danger of a tornado. Because tornadoes usually occur in flat areas, such as grasslands, radar stations are often placed in these areas (see Figure 4).

One indication that a volcano is about to erupt is that the mountain grows larger as magma moves up towards the surface. Unfortunately, the change is small and happens fairly slowly so that people rarely notice it. That is why engineers have developed devices called tiltmeters that can detect small changes in the shape of volcanoes. These devices are placed directly on the sides of volcanoes to help us predict any upcoming eruptions.

A basic way of monitoring floods is with a water gauge. A simple water gauge is just a vertical post marked with water depths and placed in rivers and streams that often flood (see Figure 5). If the water rises over a certain level, nearby communities are evacuated to prevent the loss of lives. Engineers have developed some fancier water gauges that automatically relay information to local data centers.

Procedure

Before the Activity

• Make two copies of the Natural Disaster Prevention Devices Sheet. Cut the sheets so that each student gets a strip with each of the six different devices; each sheet contains 20 sets.
• Make copies of the Map of Unawaria, one per student.
• Make copies of the Save Our City! Worksheet, one per student.

With the Students

1. Tell the students a background story about Unawaria and natural disasters: "The prime minister of Unawaria has just called me and she is worried about natural disasters causing destruction in the city of Merryville and the small city of Bliss Town. She says she wants our engineers to place some disaster prevention devices around her country to minimize the impact of the many natural hazards in and around Unawaria. Unfortunately, we have only a small budget for this project, so we only can place six different devices around the country. It is up to us to decide where these devices go so they best protect populated areas."
2. Briefly explain the six different disaster prevention devices (tsunami buoy, volcano monitor, Doppler radar, water gauge, seismometer, avalanche mortar) and where they are usually placed in order to help prevent natural disasters.
3. Hand out a map to each student and lead a class discussion about the different natural disasters that could occur in this hypothetical country.
4. Next, pass out the strips of the six different disaster prevention devices to students.
5. Have students cut along the lines to separate them into six pieces.
6. Working individually, have students decide where they think each device should be placed in order to best help prevent a natural disaster or predict a disaster so that lives can be saved. Have them glue their devices to their maps at those locations.
7. Next, have students complete the worksheet. (Note: Make sure to hand out this worksheet only after the students have completed gluing their devices on their own maps.)
8. (optional) While waiting for the rest of the class to finish, have students color their maps and devices.
9. Review the map and worksheet with the class. There are no absolute right and wrong answers as long students are able to logically justify where they placed their devices. With everyone's ideas pooled together, can we agree on what are the best placements for each device?
10. Conclude by conducting the post-activity assessment activities described in the Assessment section.

Vocabulary/Definitions

avalauncher: A device used to launch explosives (an avalanche mortar) onto avalanche-prone slopes in order to trigger small avalanches so that large avalanches do not form.

buoy: A floating device.

DART: DART = deep-ocean assessment and reporting of tsunamis system. A collection of sensors and buoys that detect potential tsunamis and warn people in coastal areas.

Doppler radar: A type of weather radar that is used to detect precipitation and track the speed and direction of a storm.

engineer: A person who applies her/his understanding of science and mathematics to creating things for the benefit of humanity and our planet.

seismometer: A device for detecting and measuring the intensity of an earthquake. Also known as a seismograph.

tiltmeter: A device placed on a volcano that can detect changes in the size of the volcano due to increased magma volume. Used to help predict impending eruptions.

Assessment

Pre-Activity Assessment

Discussion Questions: Solicit answers to the following questions and explain to students that these questions will be answered as we explore the activity.

• Is it necessary to monitor every natural hazard in order to prevent a natural disaster? (No, many natural hazards exist in remote areas and are no threat to humans.)
• Can anyone name any devices or methods we use to predict, eliminate or minimize the effects of natural disasters? (Example answers: Seismometers, avalanche mortars, water gauges, volcano tiltmeters, tsunami buoys, Doppler radar, sensors, communication and warning devices, weather satellites and forecasts, levees, structures, fire fighting equipment, etc.)

Activity Embedded Assessment

Activity Worksheet: Have students complete the Save Our City! Worksheet; review their answers to gauge their mastery of the subject. After students finish working individually on worksheets, have them compare answers with a peer, giving all students time to finish their worksheets.

Voting: Have students vote on the following true/false questions and then explain the answers.

• True or False: Avalanche mortars prevent avalanches from occurring. (Answer: False, avalanche mortars trigger small avalanches so that large avalanches are not likely to occur.)
• True or False: Tsunami buoys should be placed close to shore in order to better protect the coast. (Answer: False, tsunami buoys should be placed in the ocean, far from shore, so that residents have time to evacuate.)
• True or False: A seismometer can detect a strong earthquake anywhere in the world. (Answer: True)
• True or False: Tiltmeters measure the tilt on an avalanche slope. (Answer: False, tiltmeters measure the change in the shape of a volcano.)
• True or False: Tornadoes typically form over flat areas such as grasslands. (Answer: True)

Post-Activity Assessment

On the Map/Worksheet Discussion: Draw a rough version of the Map of Unawaria on the classroom board and have several students come up to show where they think the devices should go. Have students explain their reasoning for choosing their locations.

Worksheet: After students complete the Save Our City! Worksheet, explain that they work for an engineering firm and the interns made their best guesses as to where the devices should be located. Now, as expert engineers, the students can help the interns place the devices correctly. Review and discuss the worksheet with the entire class. Have the class generate a list of "mistakes" and have them describe "improvements," explaining why they would move the devices elsewhere.

Safety Issues

• Be sure students are careful with scissors, or do the cutting in advance.

Troubleshooting Tips

Remind students that there is no one right place to put each device, although some placements do not make sense (such as a tsunami buoy placed in the mountains). Their placement decisions may be correct as long as they can provide good reasoning for where they place their devices.

Activity Extensions

Have students identify other natural hazards on the map or add a natural hazard to the map. Then, have them use an existing device or design their own devices that would help keep the new natural hazard from becoming a disaster.

Activity Scaling

• For lower grades, discuss as a class where the devices would be best placed and go through the worksheet together. Make sure all the students are writing down the class decisions (that is, the mistakes on the map) throughout the discussions.
• For upper grades, tell the students how the natural disaster prevention devices work, but do not give them information on where they are usually placed. Challenge them to decide where to place the devices without this information.

References

Copyright

Contributors

Supporting Program

Acknowledgements

The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education, and National Science Foundation GK-12 grant no 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.