# Physics of Tsunami By: Febdian Rusydi Aree Witolear.

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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. San Andreas Fault 1 23

Earthquake at Sea 1 st possibility:

Earthquake at Sea 2 nd 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: 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 = 100- 200 meters apart Tsunami Wave Speed = 800-1000 kph Wave Period = 10 min-2 hours apart Wave Length = 100- 500 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*10 18 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 ex- villages

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!DONATE YOUR MONEY FOR ACEH!

Poem by Heri Latief

The End Credits: BBC, How Stuff Works