Finally, review and summarize the forces involved in landslides,
referring to the illustrations on the handouts. Show the photos or slides
again, and ask students to explain what they observe in terms of
physical forces.
ADA P T A T I ON S AND E X T E N S I ON S
Invite students to test the effect of the material by repeating steps 6
and 7 above with dishes of potting soil, gravel, and other materials.
ACTIVITY THREE
T
SUNAMI
: W
AVES
T
HAT
P
ACK A
W
ALLOP
VOCABULARY
Amplitude:
a measure-
ment of the energy of a
wave. Amplitude is the
displacement of the
RA T I ONA L E
Underwater earthquakes can cause very powerful seismic sea waves
commonly called tsunami or (incorrectly) tidal waves. These waves
can devastate a coastal community because of the tremendous amount
of energy they carry.
F OCU S QU E S T I ON S
How do earthquakes cause seismic sea waves?
What kinds of energy transfers are involved?
What precautions can people take to limit tsunami damage?
OB J E C T I V E S
Students will:
1. Prepare and present a class report that reflects their own research on
seismic sea waves.
2. Describe the characteristics of an average seismic sea wave in terms
of speed, wavelength, and period, and predict its effects on a coastal
community.
3. Calculate the energy of the disturbance (sea floor motion) that
causes an average seismic sea wave.
MA T E R I A L S
Q
Master 2.4f, Teacher Background Material
Q
Student copies of Master 2.4g, Tsunami Event Reports
Q
Student copies of Master 2.4h, Seismic Sea Waves Activity Sheet
Q
Transparency of Master 2.4i, Wave Characteristics and Energy
Q
Overhead projector
Q
Student copies of Master 2.4j, Seismic Sea Waves Energy Analysis
medium from zero or the height of a
wave crest or trough from a zero
point.
Period:
the time between two
successive wave crests.
Run-up elevation or height:
the
highest attitude above the tide line,
in meters, that the water reaches as
it is forced up on land by a tsunami.
Seismic sea wave:
a tsunami
generated by an undersea
earthquake.
Tsunami:
a potential destructive
ocean wave created by an
earthquake or other large-scale
disturbance of the ocean floor. This
Japanese word has the some form in
both the singular and the plural.
Wave crest:
the highest point a
wave reaches. The lowest point is
called its
trough
.
Wave height:
the vertical distance in
meters from a wave’s crest to its
trough. (This measurement will be
twice the amplitude measured for the
some wave.)
Wavelength:
the horizontal distance
between two successive crests,
often measured in meters.
Q
Copies of Master 2.4k, Seismic Sea Waves Research and Report
Form, one for every two students
Q
A large coil, telephone cord, or hose for demonstrating wave action
Q
Numerous student copies of Master 2.41, Grading Matrix
A G U
/
F E M A
96
S
E I S M I C
S
L E U T H S
