Physics of Tsunami
By:
Febdian Rusydi
Aree Witolear
Part 1
Earthquake
Causes of Earthquake
1. Volcanic eruption
2. Meteor impacts
3. Underground
explosions (like
nuclear tests)
4. Movement of
plates (tectonic)
Plate Tectonics
Lithosphere 
Comprised of many
plates that slide over
the lubricating
athenosphere layer.
Why does it move?
Fluid (magma)
underneath is moving all
the time.
Plate Tectonics
At the boundaries between plates
1. Plates slide against each other
2. Plates move apart  magma
flows up to the surface
3. Plates push together  one
subducts the other, or neither
plate subducts under the other.
1
2
San Andreas Fault
3
Earthquake at Sea
1st possibility:
Earthquake at Sea
2nd possibility:
Part 2
Tsunami
Tsunami
Tsunami (tsoo – nah – mee)
Tsu (harbor) & nami (wave)
“A natural phenomenon consisting of a
series of waves generated when water in
a lake or the sea is rapidly displaced on a
massive scale” (www.wikipedia.org)
Theory of Waves
Traveling Wave
• Wave moves energy,
not matter!
• Energy  E ~ f ~ v/ 
T = 1/f
Ocean Waves
- Wind blows  grab water molecules
- Water’s surface stretches  ripples (capillary
waves)
- Ripples moves  more molecules collected
- Size and momentum increase  reach the
beach
Tsunami Waves
Tsunami At Sea
• Unlike a normal wave,
energy of a tsunami
moves through the water,
not on top of it.
• Velocity: v  g  d
d = water depth
Moves fast in deep
waters  400 km/hour!
• No more than 1 meter
high  can not be seen
“…we only felt that the
waves were larger than
normal.
Only that!”
- Rusli, a fisherman
Energy Loss
Waves loses energy as it moves away from its
source
Energy loss rate ~ 1 / wavelength
 The longer the wavelength, the less energy it
loses
Tsunami wavelength = 200 km!
 Energy is almost constant far from epicenter
Normal Wave vs Tsunami Wave
Ocean Wave
• Speed = 8-100 kph
• Wave Period = 5-20
seconds apart
• Wave Length = 100200 meters apart
Tsunami Wave
• Speed = 800-1000
kph
• Wave Period = 10
min-2 hours apart
• Wave Length = 100500 km apart
As Tsunami Moves…
At the Beach
• Shallow water compresses the energy
• Tsunami moving away the beach: fast, short height
 v &  increase, A decrease
• Tsunami moving toward the beach: slow, tall height
 v &  decrease, A increase
Part 3
Impact
Some Pictures from Satellite
Tsunami 12/26
•
•
•
•
Magnitude of earthquake = 9.0 SR
Slipped plate length = 1,200 km
Slip over = 15 m
Height of wave reach up to 30 m with speed ~
800 km/hr
Detected Earthquake
Tsunami Animation
Tsunami in Aceh
Magnitude: 9.0 on the Richter scale
The Energy possessed (roughly):
~ 5 MTons of TNT = 2*1018 Joules
~ 2 x explosive energy during all WW II
~ 30% energy consumed in USA a year
~ 70 days Hurricane Isabel
Impact on Earth
• Some smaller island southwest Sumatera
moved ~ 20 m to southwest
• Northern tip of Sumatera moved ~ 36m to
southwest
• Some small islands near Aceh province
are gone forever
• New lakes/rivers created in ex-land in
Aceh, disconnecting transportation to exvillages
What we believe
• This is not a disaster, but a miracle
• Miracle that changes many things in our
social life!
• The miracle is not finished yet
• We have a responsibility, to finish the
miracle:
• DONATE YOUR MONEY FOR
ACEH!
Poem by Heri Latief
The End
Credits: BBC, How Stuff Works