M A S T E R P A G E
Seismic SeaWaves
Energy Analysis
2.4j
Name
_________________________________________________________________
Date _____________________
To calculate the minimum energy needed to cause an average seismic sea wave, we can calculate the work
needed to give a particular volume of ocean water some gravitational potential energy. In essence, this means
calculating the product of the force needed to lift a particular volume of water and the height to which it is lifted.
Using the average values from tsunami research to carry out the following steps, calculate the energy released by
an earthquake on the sea floor that starts a seismic sea wave.
1. What is the average sea floor area that moves in an earthquake that results in a seismic sea wave?
2. Knowing that the average ocean depth (h) is 3.8 km, what volume (V) of water is moved in the disturbance that
causes a seismic sea wave? (Use the formula V = Ah.)
3. This volume of ocean water has a certain mass. Knowing the density (D) of ocean water to be 1.03 kg/m
3
,
calculate the mass (m) of the water moved by the quake. (Use the formula m = DV.)
(
note:
1 km
3
= 1 x 10
9
m
3
)
4. To lift that mass of ocean water requires a force that is at least equal to water’s weight. Using 9.8 m/s
2
as the
acceleration due to gravity (g), calculate the force (F) needed to lift that much ocean water.
A G U
/
F E M A
121
S
E I S M I C
S
L E U T H S
