Chapter 13, Lesson 4, "Earthquakes"

Materials:

• Worksheet, "Earthquakes"

Objective:

• Students will explain what causes earthquakes.
• Students will describe earthquake waves and explain what a seismograph does.
• Students will explain how an earthquake is located and how its strength is measured.

Anticipatory Set:* Teacher will set up a model of an earthquake. Place two small boards next to each other with rubber bands attached to them. Stand a few things on the boards. Put tension on the rubber bands until "earth quakes" occur. Ask the following: What geologic event is simulated in this model? How come the board don't slide gentally against one another? (sliding and static friction) Use a green twig to simulate tension on the earth as well. Put your hand on either end. Move one up and the other down to simulate the force on the earth. The twigs will eventually break. "Earthquake"

Teacher Input:* Ask the students when they had the last earthquake in Alaska. Then take them to the Alaska earthquake center's web site. Show them the data on earthquakes in Alaska. It will be very surprising to them that there were several earthquakes already that day. Point out there are over 800,000 earth quakes each year. People do not feel many of them. Show this picture and discuss what causes an earthquake. The effects of an earthquake can be seen right away in a violent quake or they may be more gradual over a period of several years. Show earthquake locations and ask. Do you notice anything about where we find earthquakes? (Earthquakes are found mainly near plate boundaries) How do we know where Earthquakes are and how big of earthquake it is. Show this diagram of how we know where they are and discuss it. Each earthquake has a focus and an Epicenter. Next show the picture of a seismograph and explain how it measures how big an earthquake is. Once it is measured it is given a Richter scale value. This is how those values work. Each number is a value 10 times greater than the number before it.

Show the students a map of the most notable Alaska Earthquakes. Surprisingly the most deadly part of an earthquake is not the movement of the earth but it is what that movement causes. Not buildings falling, highways collapsing, or people falling in cracks. Do you know what is the most deadly event related to earthquakes? The tsunami! In fact in 2004, 170,000 people died when a tsunami hit southeast Asia. Here is what that tsunami may have looked like on a global map as it moved across the world.

Because of the enormous destruction and loss of life associated with earthquakes a lot of research has went into trying to predict them. Signs of an earthquake may be, drop in well water levels, bulges in the Earth's surface, and/or a change in the rate of seismic activity. Many Tsunami warning procedures have also been implemented.

Guided Practice:* Students will answer the questions on Page 326 with the teacher.

Independent Practice:* Students will complete the worksheet on Lesson 4, "Earthquakes, Terms Review"

Check for Understanding:* Students will take a quiz on Lesson 4.

Duration:

30 minutes + 10-15 for Independent Practice (Could be longer if taken for homework).

Alaska Content Standards Addressed in this lesson:

• SCI A-4 Students will understand observable natural events such as tides, weather, seasons, and moon phases in terms of the structure and motion of the earth (Earth);
• SCI A-7 Students will understand how the earth changes because of plate tectonics, earthquakes, volcanoes, erosion and deposition, and living things (Processes that Shape the Earth);
• SCI A-9 Students will understand the transfers and transformations of matter and energy that link living things and their physical

• SCI A-15 Students will use science to understand and describe the local environment (Local Knowledge); and: