Today is out first day of natural disaster! We are talking about earth! What types of natural disaster relate to the earth/ground?
A volcano has many parts (see Figure 6). Under a volcano, from a pocket of molten rock known as the magma chamber, hot magma travels up through a fissure, called a vent. While a volcano can have more than one vent to the surface, it usually has one central vent. Magma exits the volcano at the crater, becoming lava. The crater is typically a bowl-shaped opening located at the top of the cone. If the eruption is violent, ash and rock are launched into the air. This material is collectively known as tephra. Much of the material ejected from the volcano collects on its sides. After many eruptions, enough layers, known as strata, build up to form a volcano's recognizable cone shape.
Volcanoes Types
The three main types of volcanoes are cinder cone, shield volcano and stratovolcano. A cinder cone is the most common. Also known as scoria cones, they are usually small and made of volcanic fragments from previous eruptions, called cinders or scoria. They have steep sides and typically a bowl-shaped crater (see Figure 7).
Another type of volcano is a shield volcano, which is formed almost entirely of liquid lava. The lava flows out of a vent and slowly slides down the side of the volcano. As the lava cools, it forms a broad cone of basalt. The slopes of a shield volcano are usually very gentle (see Figure 8).
And last, stratovolcanoes have the tall conical shape most often associated with volcanoes (see Figure 9). They have very steep sides and often form during violent eruptions. They are made of tephra and solidified lava.
Prediction of Volcanic Eruptions
To give people advance warning that a volcano is going to erupt, engineers and scientists are creative in designing and building devices to detect natural indicators of volcanic eruptions. Warning signs include earthquakes, gas emissions, change in magnetic field, and the swelling of the volcano itself. To monitor active volcanoes, seismometers detect the vibration of earthquakes, tilt meters detect even slight changes in the shape of the mountain (see Figure 10), and other devices monitor and measure escaping gases. Students can use the associated activity Ready to Erupt! to learn the important phases of an erruption to help predict disasters!
Explosive ash eruptions from volcanoes can shut down airports, disrupt air routes and temporarily stop air supply service to remote areas. Some of the equipment that engineers design to monitor volcanoes help people in the Federal Aviation Administration and airlines make better decisions on flying during volcanic eruptions.
Not all hills and mountains are made of the same materials. There are different types of rock, sand and soil found everywhere. Have you played with sand before? How about modeling clay? If you made a castle out of each of these materials, which one would be more likely to fall down? (Answer: The one made from sand.) One hillside made of a certain material (or materials) may be more stable than another of the same size and shape. Also, when you add water to different materials, it is hard to predict what might happen. The material something is made of is important to how well it holds up or how strong it is. Landslides are the result of gravity and friction acting on these different types of earth materials (rock, soil, sand, gravel, etc.). The best thing that an engineer can do is to develop a model of the different materials and see what happens in a landslide.
To give you an idea of how important building a model can be to predicting a landslide, let's use the example of a city in South America near the Andes Mountains that was in the path of a landslide in 1999 (see Figure 1). This city was buried in almost 1.8 million tons (1.6 million metric tons) of mud, rock, sand and other debris from the landslide. Full-size, 18-wheeled dump trucks carry about 80,000 pounds (40 tons or 36 metric tons). It would take 45,000 of these trucks to carry this much stuff away. That's a lot! Building a model of possible landslide areas helps engineers and scientists predict just how much earth material might cover a city.
Today, we are going to have some fun and learn more about landslides by creating our own mini-landslides. We are going to build mini-houses, too, and see if they get wiped out by the landslides. Since not all hills and mountains are made of the same materials, we are going to test a couple of different situations. Scientists and engineers perform these same types of experiments to understand how real-life landslides work—let's give it a try!
Earthquakes are a natural hazard that results in the very sudden and forceful shaking of the Earth’s crust. Earthquakes happen frequently at the convergence of tectonic plates. When these plates hit or slide past each other, they release built up stress. The surface where the tectonic plates slip is called a fault. The point where an earthquake occurs is called the focus of the earthquake, which can be close to or far below the Earth's surface.
The location on the Earth’s surface that is directly above the focus is called the epicenter of the earthquake. The epicenter is where most damage occurs. The release of force at the earthquake's focus creates vibrations that travel in seismic waves away from the epicenter. Earthquakes can crack walls and move foundations and may cause entire buildings to crumble. Large earthquakes can even cause loss of life and millions of dollars’ worth of damage. (Note: USGS’s “Earthquakes for Kids” offers additional information)
To keep people inside and outside of building safe in areas of high earthquake risk, civil engineers strive to design buildings that are more resilient to the damaging forces of earthquakes.
Ask students, “How do you think engineers design earthquake-proof buildings?”
Ask a few students to share their ideas, and then briefly introduce the engineering design process.
Explain that engineers ask critical questions about what they want to create or what specific problem they are trying to solve. These questions include: What are the project requirements (criteria)? What are the limitations (constraints)? This also requires conducting research on the problem. For example, civil engineers work together with scientists, as well as engineers from different backgrounds, to better understand the problem of how to design earthquake-proof buildings.
The engineering team then imagines possible solutions to the problem. This takes a lot of creative brainstorming! After making a list of solutions and some sketches of their ideas, the team of engineers plan and select their best idea.
Once the team decides on the details of the final design, they create the prototype and test it out! Prototypes are smaller models that are used by engineers to test a design. In the testing phase, the team pays attention to what needs to be changed to the model to make the product work better. The last step of the engineering design process is to improve (iterate) their design.
Ask students:
Have students share their observations. Help students notice that the structures have a large base (smaller at the top) and a cross-bracing design.
Follow-up with asking students:
After students share their responses, tell students, “Earthquake-proof buildings typically have cross-bracing which are made by two diagonals supports placed in an X manner that forms triangles, which are the strongest geometric shape. This design geometry is often seen in bracing on bridges, and it helps keep the building steady by providing lateral stability. Cross-bracing supports and balances tension and compression forces to help prevent the structure from collapsing during an earthquake.”
In this project we will explore rockets and their components to keep astronauts safe. Your challenge is to create a rocket that will protect your astronaut during take off, flight, and landing. Good Luck!
