Students are introduced to natural disasters, and learn the difference between natural hazards and natural disasters. They discover the many types of natural hazards — avalanche, earthquake, flood, forest fire, hurricane, landslide, thunderstorm, tornado, tsunami and volcano — as well as specific examples of natural disasters. Students also explore why understanding these natural events is important to engineers and everyone's survival on our planet.

Engineers learn about our planet so that humans can exist with and survive its natural events. Engineers must be aware of natural hazards and potential natural disasters in order to prevent or minimize their harmful effects on people and property. They create devices that detect natural disasters, build structures to withstand them, and invent devices to study natural hazards. Our homes must withstand the powerful forces of wind, snow, water, fire and moving earth. Specialty items to help people in natural disasters include avalanche beacons and airbags, lightning rods and all kinds of environmental sensors. Engineers also design special equipment to fight fires on the ground and from the air. Disaster earthquake flood hazard hurricane landslide natural disaster natural hazard tornado tsunami volcano After this lesson, students should be able to: Differentiate between a natural disaster and a natural hazard. Be able to name at least three different natural hazards. Describe why engineers care about natural disasters. Does anyone know what a natural disaster is? Can give me an example of a natural disaster? (Students might mention natural forces that cause destruction such as volcanoes, earthquakes, tsunamis, floods, hurricanes, tornados, landslides, etc. As they give you examples, write them on the board.) If a volcano erupts in Antarctica, where no human is affected, is it a natural disaster? What about an earthquake that no one feels? Well, these are actually considered natural hazards, but not natural disasters. The difference between a natural disaster and a natural hazard is that a natural hazard has the potential to cause damage to people, but doesn't necessarily, while a natural disaster is a natural hazard that affects human populations. For example: Volcanoes are natural hazards because they have the potential to erupt and affect humans. Mt. Pinatubo was a volcano that erupted in the Philippians in 1991 destroying communities and taking the lives of 300 people, making Mt. Pinatubo a natural disaster. Why do engineers care about natural hazards? Well, engineers need to understand natural hazards in order to understand their effects on the things they create. They also need to know where natural hazards are likely to occur, so they can prepare for keeping people safe from them. Engineers work to design communities that can either survive or minimize the impact of a natural disaster. Engineers design structures such as buildings and bridges so they do not fall down in an earthquake, they build channels to deflect lava flows from volcanoes, and they even put buildings on stilts to avoid tsunamis. Engineers also design special instruments to predict natural hazards like hurricanes, earthquakes, tsunamis and floods. Engineers develop tracking devices for thunderstorms and tornados. Engineers even work on the special devices for helping rescuers find people buried in avalanches. Engineers do a lot with natural hazards and natural disasters. Natural Hazards: What is a natural hazard? A natural hazard is any naturally-occurring event that poses a danger to human life or property. "Natural hazards" is a general term for events such as volcanoes, earthquakes and tsunamis. Types of natural hazards include: avalanche, earthquake, flood, forest fire, hurricane/typhoon/cyclone, landslide, thunderstorm/blizzard/ice storm, tornado, tsunami and volcano. Below are short descriptions of these natural hazards. In later lessons of this unit, many of these natural hazards are examined in more detail. An avalanche is a large mass of snow, ice and/or rock that is carried down a slope by gravity. Typically, the term avalanche refers to snow sliding down a mountain. Of several different kinds of avalanches, the most common and most dangerous is a slab avalanche. A slab avalanche occurs when a large section of snow can no longer stick to the side of a slope and is overcome by the force of gravity. These typically form on slopes that have an incline between 25 and 60 degrees. Most avalanche victims are backcountry skiers, but avalanches can sometimes destroy human settlements. One example is the mountain town of Montroc in France, which was hit by an avalanche in 1999 killing 12 people. Predicting and preventing avalanches can be difficult, but engineers use several methods to mitigate the impact of avalanches. Passive methods include snow fences and retarding structures that hold the snow on the slope or redirect or slow the avalanche so that it does not damage structures. Active techniques typically involve triggering small avalanches with explosives in order to prevent larger avalanches from forming. Engineers also design devices such as beacons and airbags that people can wear in the backcountry to help them survive an avalanche. A beacon is an electronic transmitter that helps rescuers find a buried person, while airbags inflate during an avalanche, keeping the victim buoyant as well as providing breathing room once the avalanche stops. Earthquakes are potentially devastating natural hazards. Earthquakes are formed as the tectonic plates that make up the crust of the Earth rub against each other. While there are approximately 8,000 earthquakes every day worldwide, almost all of these are too small to feel. Occasionally one is large and close enough to a populated area to create significant damage. Engineers work to design devices such as seismometers and lasers that can help predict earthquakes. Engineers also consider the powerful forces of earthquakes when designing structures and bridges. Floods are natural hazards that involve an overflow of water that submerges usually dry land. Of the many different types and causes of floods, the most common are periodic river flooding and flash flooding. Periodic river flooding is caused by melting snow and spring rain increasing a river's water level. Even though this type of flooding is easy to predict since the water level rises at a slow rate, these floods can still be disastrous because sometimes the amount of water is unexpected or just too much water. Flash floods occur when there is suddenly too much water for streams and rivers to contain. Usually this type of flood is brought about by rainstorms. Engineers design river gauges and weather monitoring devices to predict floods. They also design dams and levees that prevent and minimize the impact of flooding. Forest fires are natural hazards that can be tremendously destructive. Forest fires occur in heavily forested areas during the dry season. They are usually started by lightning or by human activities such as campfires. Periodic forest fires are good for the forest because they help to thin the forest and allow for new growth. Forest fires also have the potential to destroy houses and towns in or near forested areas. To minimize the impact of forest fires, engineers design special tractors that cut and clear fire lanes (forest strips in which all vegetation is removed) to halt the spread of a forest fire. Engineers also design special aircraft that drop water or chemical retardants on the fire. Hurricanes are powerful tropical storms with wind speeds in excess of 74 mph (119 kph). Hurricanes form in the warm ocean waters near the equator. A hurricane has an organized rotation with a central "eye" where the winds are calm. The eye is typically between 20 and 40 miles (32-64 k) in diameter. Surrounding the eye is the eye wall — where the winds are usually the strongest and are accompanied by heavy rain. Beyond the eye wall are rain bands, which are long thunderstorms that curve out away from the center of the storm. Damage from hurricanes is caused by the high winds, a powerful storm surge as the storm makes land fall, and inland flooding as an area is saturated with heavy rain. Hurricanes are known as typhoons in the Pacific Ocean and as cyclones in the Indian Ocean. Engineers confront hurricanes by designing specialized weather instruments and satellites to detect hurricanes and predict their paths. Engineers also design structures and sea walls to survive the storm and minimize their impacts. Landslides are similar to avalanches in that they involve gravity pulling material down a slope. Of the wide variety of types and causes of landslides, the most common are caused by heavy rains and erosion. Engineers create monitoring devices to help predict landslides, as well as design special nets, anchors and walls that support slopes and prevent landslides. A thunderstorm is a severe storm characterized by thunder and lightning. Thunderstorms are often accompanied by heavy rain, hail or (rarely) snow. The term thunderstorm comes from the thunder that accompanies the lightning. Thunder is the sound of the shockwave caused by the lightning heating and expanding the air around it. Lightning is the discharge of electrical energy that is formed as particles in the cloud rub against each other. This is similar to the static electricity that forms when you rub a balloon on your hair. Each bolt of lightning transfers 500 megajoules of electricity, which is enough to light a 100-Watt bulb for two months. Thunderstorms are dangerous and damaging because of the risk of being struck by lightning, the destruction caused by hail, the possibility of flash flooding, and the potential for tornados. Engineers design special radar to track storms and warn residents in their path. They also design lightning rods, which provide a safe path for lightning to reach the ground. Tornadoes are powerful, funnel-shaped windstorms. Tornadoes usually start as vigorous thunderstorms that form supercells. A supercell is a thunderstorm with a rotating core. This rotation is called a mesocyclone. As the mesocyclone descends, it forms a funnel cloud. Once the swirling funnel cloud reaches the ground it is called a tornado. With wind speeds of up to 300 mph (483 kph), tornadoes can be incredibly destructive. Tornadoes that form over water are called waterspouts. Engineers track tornadoes in the same way they track thunderstorms since they are usually associated. Tsunamis are large waves caused by displacement in the sea floor, typically caused by landslides or earthquakes under the ocean. The huge waves can move far inland, threatening coastal areas and wrecking havoc on communities. Engineers design special ocean buoys to detect the tsunami when it is still far out in the ocean so that people can be given advance warning to evacuate coastal areas. Volcanoes are formed when liquid magma located under the crust of the Earth finds a way to the surface. When it reaches the surface it is known as lava. Volcanoes can erupt violently with a huge explosion, spreading lava, ash and rock over a large area. Or, they can erupt more calmly, as when lava oozes out of the ground. The three basic types of volcanoes are shield volcanoes, stratovolcanoes and cinder cones. Shield volcanoes form when lava flows like a liquid creating a low and wide (shield-like) dome. Stratovolcanoes are large conical shaped volcanoes are formed by layers of deposit from explosive eruptions. Cinder cones are usually smaller and form from the scoria of a single eruption. Scoria is solidified chunks of magma. Engineers create special devices, such as tiltmeters, that monitor mountains to provide warnings of possible eruptions to the surrounding inhabitants. Natural Disasters: What is a natural disaster? A natural disaster is any natural hazard that affects human lives or property. A natural hazard, such as an earthquake that occurs at the bottom of the sea and that no one feels, is not a natural disaster, while an earthquake such as the one in Pakistan in 2005 that killed nearly 100,000 people and destroyed many and roads was a terrible natural disaster. Engineers must study and understand natural hazards and natural disasters to be able to create structures that can survive and protect people from their powerful forces. Engineers also design devices and tools that people use to detect the powerful and natural forces of our planet, as well as methods for avoiding or diverting natural events that might become natural disasters. A large slide of snow, ice or earth down a slope. Shaking of the ground caused by friction between the tectonic plates. A person who applies his/her understanding of science and mathematics to creating things for the benefit of humanity and our planet. When normally dry land is submerged with water. An uncontrolled fire in a forested area. An organized rotating storm that forms in or near the tropics. A large movement of earth down a slope. A specific disaster effecting humans that is caused by a natural hazard. A natural event that has the ability to cause destruction. A powerful storm that includes lightning and thunder. A tunnel-shaped storm characterized by high winds. A large ocean wave caused by the displacement of the sea floor. An opening in the Earth's crust through which molten lava, ash and gases are ejected. Save Our City! What is a natural hazard? (Answer: A natural event that has the power to damage or destroy property as well as injure or take lives.) We discussed that volcanoes, earthquakes, tsunamis, floods, hurricanes, tornados and landslides are examples of natural hazards. What is the difference between a natural disaster and a natural hazard? (Answer: Natural hazards are natural events that pose danger to human settlements and lives, while a natural disaster is a specific event that harmed people.) Can anyone tell us about a specific natural disaster? What natural hazards occur in the area where we live? Why are studying and understanding the natural events of our planet important for engineers? (Answer: Engineers need to understand hazards and disasters in order to create devices that can predict, prevent or minimize the impact of a natural hazard as well as design structures so people can survive them.) Discussion Questions: Solicit answers to the following questions and explain to the students that we will answer these questions as we explore the lesson. What is a natural disaster? Name a specific example of a natural disaster. Can we prevent or predict natural disasters? Voting: Have students vote on the following true/false questions and then explain the answers. True or False: Natural hazards and natural disasters are exactly the same thing. (False: Natural hazards are natural events that have destructive powers, while natural disasters are specific natural hazards that caused the destruction of human settlements and lives). True or False: The 1906 San Francisco earthquake that left nearly 300,000 people homeless was a natural disaster. (True: This earthquake was a specific event that caused lots of destruction to the people and property in the city of San Francisco). True or False: A nuclear power plant meltdown is a natural hazard. (False: A nuclear power plant is created by humans and is therefore not natural.) True or False: A fire that started by a burning candle and destroyed the personal belongings of all the people who live in an apartment building is a natural disaster. (False: This fire sounds like a disaster, but it was caused by humans and is therefore not considered a natural disaster.) Drawing: Have students make a drawing that illustrates one type of natural hazard and label it. To make it into a drawing of a natural disaster, have them show the hazard affecting people and communities. Have students discuss how an engineer might help track or predict this event. As an extension, have them act as engineers and draw a device or structure with the purpose of protecting people, warning people or predicting the timing or location of a natural hazard. Summary Questions: Ask the students and discuss as a class: What is a natural hazard? (Answer: A natural event that has the power to damage or destroy property as well as injure or take lives.) What is an example of a natural hazard? (Answers: Avalanche, volcano, earthquake, hurricane, tornado, landslide, thunderstorm, flood, forest fire.) What is a natural disaster? (Answer: A specific event in which a natural hazard did damage to a human population.) What is an example of a natural disaster? (Answer: See Table 1.) Why do engineers care about natural hazards and natural disasters? (Answer: Engineers care because they must first understand hazards and disasters before they can create devices that predict, prevent or minimize the impact of a natural hazard, as well as design structures so that can survive a natural hazard and protect people.) Have students research a specific natural disaster, making a poster that describes it. Have them talk about what natural hazard caused the disaster as well as the effects and what might have been done to prevent or minimize the impact of the disaster. As a side activity, have students learn more about potential and kinetic energy as they design and build a way to safely and accurately deliver relief goods (represented by an egg) to people in a natural disaster area with no road access. Similar to real-world engineering design teams, students must design their devices with constraints such as limited materials. Activity for grade 6, but may be suitable for grades 4-8. See the TeachEngineering Bombs Away! activity. Ask students to think about the types of natural disasters that might occur in the area in which they live. Then, imagining that a natural disaster occurs in their community, what have engineers created that would help students survive the dangerous situation? For example, if you are safe during a blizzard, what keeps you safe? Engineering examples might include: Strong roof, insulated walls, heating system, lighting, communication devices (radio, television, phones), indoor plumbing and electricity, stoves and refrigerators, warm clothing made with modern fabrics, weather predicting and warning devices, safe vehicle, etc. Have them summarize in a one-page paper. Abromeit, Doug, Anne Marie Deveraux, and Britt Overby. Forest Service National Avalanche Center. U.S. Forest Service. 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Last modified, December 10, 2006. U.S. Geological Survey. Accessed December 20, 2006. http://volcanoes.usgs.gov/ Watson, John and Kathie. Last updated October 23, 1997. Predicting Earthquakes - General Interest Publication. U.S. Geological Survey. Accessed December 20, 2006. http://pubs.usgs.gov/gip/earthq1/predict.html