Is There a Whole Lot of Shaking Going On? Make Your Own Seismograph and Find Out!

Building the Seismograph

1. This science project follows the Engineering Process. To learn more about the Engineering Process, and how it is different from the science projects that follow the Scientific Method, see this Science Buddies resource on Comparing the Engineering Design Process and the Scientific Method.
   1. For this science project, students are expected to design their own seismograph, test it, and then improve it if necessary. Basic steps are given to help guide students through the process.
   2. You can find additional information about this process from Engineering Design Process resource.
2. Determine how you will build the seismograph based on the diagram in Figure 1 in the Background tab and then build it. You may want to have an adult help you build the seismograph. When building the seismograph, here are some important steps and/or modifications you may need to consider:
   1. On the wood base, you will want to attach the wood stand so that it is positioned vertically on (and near one end of) the base.
      1. Fasten the wood stand securely to the wood base, such as by nailing upward from underneath the wood base.
      2. You can attach wire (or cord) between the wood stand (on its back and sides) and the base to help to keep the stand stable.
   2. Attach the mounted paper roll (roll of adding machine paper) and take-up spool (smooth sided can) on the other end of the base.
      1. Mount the paper roll and take-up spool to the wood support blocks before attaching everything to the base.
         • Figure out how best to arrange the paper roll and take-up spool on dowels attached to the wood support blocks.
         • Both the paper roll and take-up spool should be able to rotate. The take-up spool should rotate when you crank its wood dowel; the paper roll can turn either with its wood dowel or separately from the dowel.
         • If you want to be creative, see if you can devise a way to make the paper roll feed onto the smooth can automatically so that you do not have to crank the can by hand. You might try buying a miniature battery-operated motor that can turn the wood dowel of the can.
         • Tape down the end of the paper roll onto the can so that when you crank the can, the paper should wind up around the can and cause the paper roll to rotate as it feeds paper to the can.
         • If you have a drill, you can mount the two wood dowels in holes drilled through the two wood support blocks. If you do not have a drill, saw two slots into the upper edge of each wood support block and then drop the dowels into these slots.
   3. Before attaching the beam to the stand, you can attach a pen to the end of the beam.
      1. You can do this by using a hand drill to drill a hole through the end of the beam and placing a pen in the hole.
      2. The pen must write easily when pulled down onto the paper roll by the brick. Cap it when not in use. You may try substituting a soft lead pencil, a charcoal pencil, a crayon, etc.
   4. To attach the beam to the stand, you can use a hand drill to drill holes in the beam and stand and then connect them together with a wooden dowel.
      1. When deciding how high to attach the beam on the stand, consider what the height of the mounted paper roll is.
      2. To make the wood beam hang level over the base, you can fasten the round-headed screw, bolt, or nail securely into one end of the wood beam. This screw will rest against the wood stand, making the wood beam hang level. To help the screw stay in place and not slip off of the wood stand, drill or carve a small hole 1/4-inch deep out of the stand and slightly larger in diameter than the screw head. The head of the screw can sit in this hole and press against the wood stand.
   5. Attach a weight (brick) to the beam to keep it from moving due to tiny vibrations.
      1. Make sure the pen writes easily when pulled down onto the paper roll by the brick.

Testing the Seismograph

Here are some ideas for testing the seismograph. You can probably think of other ideas on your own. As you test your seismograph, think of ways in which you can improve it. Can you make your original design even better? You can make some adjustments and test it again to find out.

1. Have a helper jump up and down on the floor near the seismograph.
   1. How does the seismogram change as the jumping person moves farther away? Make measurements with the person at a distance of 0.5, 1, 2, 4, 8, and 16 meters (m) away from the seismograph. Make a graph of seismogram peak height (in centimeters [cm], on the y-axis) vs. distance of your helper from the seismograph (in m, x-axis). You could also use the seismograms themselves on your display board.
   2. How does the seismogram change if the person jumping is heavier or lighter? Pick a distance from your first experiment where the pen moved noticeably, but did not cover its full range of motion on the paper. Make a series of seismograms with helpers of different weights jumping up and down at that fixed distance from the seismograph.
   3. How does the seismogram change when you vary the substrate on which it is standing? For example, compare placing the seismogram on a wooden floor vs. a concrete slab (like your garage floor), or on a table vs. directly on the floor, or on your lawn vs. a hard-surfaced playground.
2. Safety note: adult supervision required for outdoor measurements near traffic. You could also try your seismograph at different locations outdoors. For example, if you place the seismograph on a sidewalk, can you see vibrations from nearby foot or vehicle traffic? Can you identify when larger vehicles, such as trucks or buses, pass by?