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Nathan Moore, Josh
Schuster, Dan Krause, Sean Hignite
SIGN
PAGE
TABLE
OF CONTENTS
1.
UNPREDICTABLE EARTHQUAKE SIGN PAGE
2. ENGINEERING FOR DISASTER
SIGN PAGE
Unpredictable
Earthquakes Sign Page
What to Do:
- Make
sure that the green sliding plate is as far away from you as
possible.
- Grab
the handle of the exercise band.
- Gently
pull the band toward you until the plate slips and suddenly jolts
toward you.
What’s Happening?
This
model is demonstrating how an earthquake works. The cause of most
earthquakes is the movement of the plates that make up the earth’s
surface. Earthquakes occur at fault lines where tectonic plates meet. At
the fault line, rocks are stressed and store energy like a spring as the
plates on each side of the fault slowly move. You create the same effect
by pulling the exercise band toward you gently. At times, the rocks are
no longer able to withstand the stress, and an earthquake occurs. Rocks
grind together or break apart, causing a great release of energy. If you
continue to pull the band, the plate will eventually slip and move
quickly toward you. This is simulating what occurs in an earthquake as
energy is released.
However,
plate movements can not be easily predicted. Just as you did not know
when the plate would slip, scientists have only an abstract idea of when
an earthquake will occur.
Engineering for
Disaster Sign Page
What to Do:
- Cause
an earthquake by gently pushing the suspended plywood piece with
building attached to it.
- Compare
how the building without base isolation reacts to the earthquake to
how the building with base isolation acts went an earthquake occurs.
What’s Happening?
This exhibit demonstrates one way in
which engineers “earthquake-proof” a building. This method is called
base isolation. Base isolators separate a building from the ground,
instead of rigidly anchoring it in the ground. If the building was
anchoring firmly in the ground, all the force of the earthquake would be
directly applied to the building. When the frequency of the earthquake
matches the building’s natural frequency, or the number of times the
building sways back and forth each second, the building will collapse
(in real life, not in the exhibit). Notice how the building without base
isolation moves violently.
As
the ground moves during an earthquake, the base isolators absorb some of
the movement, while at the same time, lowering the frequency of the
building, and the building does not sway dramatically. Observe how the
model building with base isolation sways at first, but soon stabilizes
and much of the earthquake’s force is absorbed by the springs.
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