Earthquakes

Lesson 10: Introducing Earthquakes What do you think causes earthquakes? What do you think are some of the effects of an earthquake? What risks do you think an individual might face during or after an earthquake? How do you think scientist study earthquakes? Where do you think most earthquakes occur?

What is an Earthquake?a Earthquakes are the shaking and vibrating of the earth. Large and sudden releases of energy cause earthquakes. The energy is released when movement occurs along large “cracks” in the earth’s outer layer. More than 90% of all recorded earthquakes happen this way. Melted rock on its way to the earth’s surface can also cause earthquakes. This usually happens before a volcano erupts. Only about 5% of earthquakes are directly related to volcanic activity.

What is an Earthquake?b Earthquakes are beyond human control. People know they will happen, and some people are working to reduce the risks associated with them. Seismologists—scientists who study earthquakes– have made great progress in studying the events that come before an earthquake. They attempt to use these events to predict when the next earthquake might occur. The latest technology makes use of special satellites that monitor movement of the earth’s outer layer. This technology is being used along the San Andreas Fault in California, in Alaska, an in parts of the Himalayas.

Where do Earthquakes Occur? The black dots represent where earthquakes have happened. Clusters of dots are the edges of the earth's tectonic plates.

“The Day the Earth Shook” Questions How does the ground appear to move during an earthquake? What are possible causes of an earthquake? What are some destructive, or negative, effects of earthquakes? Why do you think more people were killed in Kobe, Japan, than in California, when both earthquakes were of similar strength and occurred in heavily populated cities?

California highway after earthquake in 1989. A picture of the 2004 tsunami in Thailand.

Seismic waves All seismic waves produce ground motion (jolting and shaking of the earth) P-waves (primary waves) cause vertical shaking at the point of contact S-waves (secondary waves) cause horizontal shaking at the point of contact P-waves and S-waves are referred to as Body waves because they travel through the body of the earth. Surface waves also cause horizontal shaking P-waves are far less destructive than S-waves or L-waves(surface waves) Earthquake waves radiate outward in a sphere in all directions from the point of focus

Inquiry 11.1 Testing the Motion of Waves How does the ground move during an earthquake? What are some of the effects of this movement? We will be observing how vibrations, such as those caused by earthquakes, travel as waves and how earthquake waves cause ground motion.

Inquiry 11.1 Testing the Motion of Waves b Draw how the spring moves with each demonstration Push and pull (compressional waves) Side to side (transverse waves) Energy from an earthquake moves through earth and on or near its surface in waves You will use a spring to model earthquake waves.

Inquiry 11.1 Testing the Motion of Waves c Predict which type of wave might move the fastest, which might cause the most damage to buildings on the earth. Complete Student Sheet 11.1 Stimulating the Motion of Earthquake Waves

Earthquake Survival Kit It is very important to be prepared for an earthquake, especially if you live in an earthquake-prone area. You have been hired to design the ideal kit. Your kit must meet several minimum requirements: It should provide supplies for a family of four. It should provide enough supplies for three days. It should be able to be stored for long periods of time without spoiling. As a group prepare a list of items that you would include in your kit, giving both the item name and quantity Remember that after a major earthquake many of the things we take for granted will not be available.

Earthquake Survival Kit Kit Example 1 Kit Example 2 Kit Example 3 American Red Cross

Lesson 12:Recording Earthquake Waves Inquiry 12.1 Recording Vibrations Setup: adjust the pen in the clip so that it touches the paper (marks the paper) Slowly pull the paper strip through the paper frame, do not shake the table at all Check to see if the pen is marking the paper, if it is not then you need to adjust you pen, if it is then you should label that section of the paper as the “Control- no vibrations” do not tear off this section of the paper. In your notebook describe how the ink on the paper looks. Why does it look that way?

Lesson 12:Recording Earthquake Waves Inquiry 12.1 Recording Vibrations As one person slowly pulls the paper through the frame, have a second person do the following: 1. Pound on the front of the table parallel to the seismograph arm. Label the markings on the paper as “Parallel” 2. Pound on the side of the table perpendicular to the seismograph’s arm. Label the markings on the paper as “Perpendicular” 3. Pound on the surface of the table. Label the markings as “Surface”

Lesson 12:Recording Earthquake Waves Inquiry 12.1 Recording Vibrations You have just tested the variable of direction and how it affects earthquake vibrations. There are two other variables to test, location and force. How would you go about testing these variables? Record your thoughts in your notebook.

Catastrophic Events: Earthquakes http://earthquake.usgs.gov/recenteqs/ http://earthquake.usgs.gov/4teachers/ Earthquake survival kit pg406f