Lab #1
Build You Own Seismograph
Objective:
Students will gain a greater
appreciation of how a seismograph works,
and a better understanding of recordings of ground motion that they see
on seismograms.
Activity:
In small groups of 3-4 students,
students are aked to design and construct a seismograph
using common household and craft materials provided. Students will
demonstrate to the class how their seismographs record motion.
Procedure:
Begin with a demonstration in which the students jump up
and down at
various distances from the AS1 and then look at the resulting
seismogram on the screen. This will give them a feel for how sensitive
the AS1 is and what these non-quake (noise) disturbances look like on a
seismogram. Cover the AS1 so that the students don’t see it before they
do the lab. We want them to think through this Build Your Own
Seismograph exercise from first principles, without being too
biased
by what the mechanism of the AS1 looks like. Try jumping very near the
seismograph and then jumping the same amount progressively farther away
from the AS1 to see how the resulting signals compare on the screen
(and how the amplitudes of the signals decay with distance).
Also, try one student, then two students, then more students jumping,
etc. to see how much bigger the signal is on the screen as more
students jump.
Next ask the students to think of a
creative way to measure seismic
waves generated by an earthquake using some of the materials provided.
Ask them to draw a clear diagram of their seismograph, and label all
the parts. For homework, ask them describe how their seismograph works.
A good design would be:
- capable of determining the
relative size of each disturbance
it measures;
- capable of measuring
vibrations continuously for at least several
sec;
- capable of measuring
vibrations from three different sources:
a bang on or shaking of the table holding the seismograph; a person
jumping up and down on the floor next to the table on which the
seismograph is located; and a ball bounced off of a wall or floor
nearby.
After the designing and building of
the seismographs have been
completed, each team should present to the class how their seismograph
works. After each group presents their design, the teacher will give a
brief description of how seismographs (including the AS1) record ground
motion.
Reflection:
How can your seismograph design be
improved?
What elements of your seismograph are
similar to seismographs used by
seismologists? What elements are different?
What were some of the challenges you
encountered in designing and
building your seismograph? How did you try to solve those problems? Did
you succeed in solving those problems?
What are the physical principles
underlying the mechanism of how your
seismograph measures ground motion?
Can you think of any other reflection
questions that would be
appropriate for this exercise? If yes, what is your question, and how
would you answer it?
Suggested list of
materials for this
exercise:
· masking tape and/or duct tape
· weights or sinkers
· empty paper towel rolls or
toilet paper rolls
· coil springs
· straws
· paper
· paper plates
· paper cups
· pipe cleaners
· marbles
· pens and pencils
· bouncy ball for demos
· string or wire
· scissors
· miscellaneous items brought
to class by the students.