Earthquake Waves And Their Destructions

Sharione O. Mays               Donald Morrill
                               6011 S. Rockwell Street
                               Chicago IL 60629
                               (312) 535-9288

Objectives:

1. Students will learn characteristics of primary waves and secondary waves. 
2. Students will learn how to measure the magnitude of waves.
3. Students will learn how to find the epicenter of earthquakes.
4. Students will learn why waves are more destructive in some areas than others. 

Materials:
Activities are recommended for groups of four.
ropes, slinky toys, graphing paper, pencils/markers, ring stands with cross bars
carts with wheels, large floor-size erasable world map, 2 liter clear plastic
bottles, sand, tin foil pans, plastic and wood model houses, containers of  
water, stop watch, and spring scales.

Strategy:

Introduction: Today, we are going to investigate the two types of earthquake 
waves.  They are surface waves and body waves.

Vocabulary Building through discovery:  Looking at the word "surface".  Through
the use of questions, the students should be able to infer its meaning by 
directing the students to the three parts of the earth [crust, mantel, and 
core].  "Surface" should be similar to the crust of the earth.  "Body" should
be similar to the earth's mantel and core.
Ex:  What part of the earth would be the surface?
     What part of you is the body?
     What parts of earth would represent the body?

First, we will be discovering the two kinds of body waves. 

Activity:  Those "Jumping Waves"

1.  Give each group a jump rope and let them create waves.
2.  Allow one student from each group to draw the kinds of waves created.
3.  Use the drawings to identify the kind of waves that ropes create as being 
    "transverse waves". 
4.  Label the various parts of a transverse wave.  The "crest" can be the high 
    density.  The "trough" can be your low density.  "Wavelength" must have one 
    crest, and one trough. 

Activity:  Those "Slinky Waves"

1.  Give each group a slinky, and allow them to create more waves.
2.  Allow one student from each group to draw the kinds of waves created.
3.  Label all the waves that are "transverse waves", and identify the new
    waves as a "compressional wave".
4.  Label the parts of the "compressional wave".  The part of the slinky that
    is tight or close together is called "compressed".  The loose part of the 
    slinky is known as the "rarefaction".

Activity:  The "Race"

1.  Take the longest slinky, and a spring scale.  At various tension, let the 
    students use a timer to see which waves travel the fastest.  Take at least 
    three timings.  "Compressional Waves" should win this race.  Therefore, we 
    are going to call them "Primary Waves" or "P Waves" for short.  Now, 
    "transverse waves" came in second place, we will call them "Secondary Waves" 
    or "S Waves". 
2.  "Surface Waves" always occur at the surface or the "crest" of the earth.
    This wave rides on top of the " P Waves" and the" S Waves", so it is called
    the "Love Waves" or "L Waves". " Surface Waves" are the most destructive
    wave.
    "Compressional Waves" displace soil, sand, and rocks in front and back along 
    its path.  "Transverse Waves" displace material perpendicular along its 
    path. 

    The first signal of an earthquake is a sharp thump, compressional waves, 
    shear waves and finally the ground rolls caused by surface waves. 


Activity:  Measuring Waves with a seismograph

1.  Take a ring stand attach a string long enough to reach the surface of the 
    cart. 
2.  Tie the other end of the string to a marker, so that, the tip of the marker 
    touches the graphing paper. 
3.  Make a chart on the graph paper.  Let the y-axis represent magnitude, and 
    the x-axis distance. 
4.  Next, shake the table to create an earthquake using low intensity to high 
    intensity. 

    There are two ways that scientist measure earthquake waves.  They use 
    magnitude, or intensity.  The seismograph measures "magnitude" which deals 
    with the waves along.  "Intensity" measures destruction of earthquake waves 
    by the number of deaths, and other visual means. 

    When I refer to "low" or "high" intensity, it will relate to force or energy 
    applied. 

Activity:  Locating, and Plotting Epicenters

1.  Place a large erasable world map on the floor.
2.  Using prepared card containing latitudes, and another set with longitudes
    coordinates of various earthquake locations.  Give each student a card.
3.  Call out coordinates in pairs.
4.  Next, give each child a toy car.  They are to place their cars on the 
    appropriate latitude or longitude lines.
5.  Roll the cars on their appropriate line and mark the point of intersection.
                                                                            
    Before this activity, you may take the students through directions finding
    hemispheres, locating continents and oceans.

    Epicenters are the origin of earthquakes.

Activity:  Is the Earth a Solid Core?  Liquefaction

1.  Take a tin pan and pour sand into it.  Just enough to cover the bottom.
2.  Pour just enough water to saturate.
3.  Pour another layer of sand.
4.  Place a wooden house, or a monopoly game house on top of the sand.
5.  Create an earthquake, either shake or strike the desk.

    What happened to the house?

Activity:  Liquefaction in a Bottle

1.  Pour sand into a plastic or jar bottle using a funnel.  The sand
    should measure about 2-3 inches in height.
2.  Use a large nail and put a hole into the lids.
3.  Put water into another plastic bottle.
4.  Take the lids and run plastic tubing.  Make sure the tubing is long
    enough to reach the sand in the other bottle.
5.  Drop your model house into the bottle of sand.
6.  Put the lids on both bottles.
7.  Squeeze the bottle containing the water, and saturate the bottle containing
    the sand.
8.  Create an earthquake.

    What do you observe?

    Liquefaction occurs because of unconsolidated sand, clay or rocks.
    Location is important in deciding on where you should live in this 
    world.  

9.  Review the activity on epicenters.  Bring out the floor map.  

    Where do we find most of our epicenters located?
    Are they located by water?
    What type of soil do you find?
    Is water important to creating liquefaction?
    Where would you choose to live?