Lesson 4: Earthquakes and Moving Plates
Earthquakes happen quickly, but the pressures that build up to cause them happen over a long period of time as tectonic plates shift. Today you will learn more about what causes earthquakes and how earthquakes can affect the areas where they occur.
Stuff You Need
- Dirtmeister's Nitty Gritty Planet Earth by Steve Tomecek
- 10' piece of rope* (Activity 2 - optional)
- 18-24 sugar cubes
- 3 pieces of cardboard
- clay (kit)
- colored pencils
- sand (kit)
- Slinky or Slinky Jr. (kit)
- soil (kit)
* - denotes an optional material that may or may not be needed
Ideas to Think About
- How has your own environment changed in the past?
- How do sudden changes in the environment affect living things?
Things to Know
- Seismologists are scientists who study earthquakes.
- Plate boundaries are where tectonic plates meet, while faults are breaks in the Earth's crust where rocks can move past each other.
- The epicenter is the focus point of an earthquake on the Earth's surface.
- Know that the effects of an earthquake on any region vary, depending on the size of the earthquake, the distance of the region from the epicenter, the local geology, and the type of construction in the region. (S)
- Know that lithospheric plates the size of continents and oceans move at rates of centimeters per year in response to movements in the mantle. (S)
- Understand that earthquakes are sudden motions along breaks in the crust called faults and that volcanoes and fissures are locations where magma reaches the surface. (S)
Introducing the Lesson
Today your child will look at earthquakes and how they are caused by the slow movement of tectonic plates. She will do a demonstration to explore how a building's shape and the material under it affect the building's sturdiness during an earthquake.
Materials: Dirtmeister's Nitty Gritty Planet Earth by Steve TomecekRead pages 34-39 and 42-43 of Dirtmeister's Nitty Gritty Planet Earth and then answer the following questions.
- What are some situations that can cause an earthquake?Your child should understand that the most common situation is rocks at faults moving against each other. The book also mentions the eruption of a volcano or the collapse of an underground cave as possible causes.
- During an earthquake, what type of waves typically does the most damage to buildings? Why do you think they are so damaging to buildings?Surface waves. Answers will vary, but your child should understand that these waves occur on the Earth's surface, so the ground right under buildings would be shaking.
- What is the device or instrument that scientists use to measure the strength of an earthquake? What scale is used to communicate that measurement?seismograph; Richter magnitude scale
- What are tsunamis?Tsunamis are giant waves caused by undersea earthquakes. They can travel far across the ocean and cause a lot of damage.