1. English for young physicists WS 09/10 Presentation by Svende Braun
Tsunami
English for young physicists
WS 09/10
Presentation by Svende Braun

2. Outline 1. Motivation 2. Facts 3. Physical Background
4. Mathematical Description
5. Outlook
6. Sources

3. 1. Motivation
Tsunamis are not rare, with at least 25 tsunamis occurred in the last century
2004 Indian Ocean tsunami on 26th of december
Killed over people

4. 2. Facts 2.1 In general
Tsunami is a series of water waves that is caused of the displacement of a large volume of water
often called flood waves, but have nothing to do with tides, flow or wind
Cause catastrophic desaster on shore

5. 2. Facts 2.2 Etymology
tsunami comes from the Japanese, meaning „harbor“ (tsu, 津) and „wave“ (nami, 波)
Japanese fishing man returned home and found their harbor destroyed, allthough no wave was seen on open sea

6. 3. Physical Background 3.1 Formation of tsunamis
86% develop after earthquakes
3 earthquake conditions:
occurs just below a body of water
is of moderate or high magnitude
displaces a large-enough volume of water
Other reasons: volcanic eruptions, underwater explosion, landslides and bolide impacts

7. 3. Physical Background 3.1 Formation of tsunamis

8. 3. Physical Background 3.2 Propagation of tsunamis
Waves represent movement of energy
Wave propagation: oscillation of steady position
rise und fall of water level
reset force gravity
 heavy waves

9. 3. Physical Background 3.2 Propagation of tsunamis
Different to waves made of turbulences
the whole water head is moving  fundamental wave
describe a tsunami with two parameters:
- mechanics energy E
- wave period T

10. 3. Physical Background 3.3 Velocity
Example: water level ocean 5km
 v=800km/h
Near to the shoreline:
vertical movement  horizontal laminar flow
 quite high velocity

11. 3. Physical Background 3.4 Wavelength
lies between 100 and 500 km
wind waves 100 m
flat water waves: wavelength much bigger than ocean level
 transport big amount of water with little loss of energy

12. 3. Physical Background 3.5 Amplitude
Big wavelength:
On the ocean amplitude is low
Only some decimetres above sea surface
 Tsunamis pass the sea unnoticed

13. 3. Physical Background 3.6 Striking coast
Water becomes shallow
Wave shoaling compresses wave
Velocity slows below 80km/h
wavelength diminishes to less than 20 km
amplitude grows enormously  visible wave
Energy gets more focused

14. 3. Physical Background 3.6 Striking coast

15. 3. Physical Background 3.7 Drawback
First part of tsunami reaches land is a trough
wave's arrival after half of the wave's period
water along shoreline recedes dramatically
exposing normally submerged areas
drawback can exceed hundreds of meters

16. 4. Mathematical description
Tsunamis are pulselike waves that do not obey the superposition principle, and do not disperse

17. 4. Mathematical description 4.1 Korteweg-de-Vries-Equation (KdV)
Mathematical model of waves on shallow water surfaces
notlinear partial differential equation of third order:
Is based on wave equation Ψ

18. 4. Mathematical description 4.2 Soliton
solutions of KdV equation
self-reinforcing solitary wave packet or pulse
Characteristics:
- High amplitude  high group velocity
No dispersion
- Notlinear

21. 5. Outlook tsunamis have caused a lot of damage in the past
 neccessary to get a better understanding of this force of nature
Find solutions like early warning systems

22. 6. Sources Solitonen in Natur und Technik - Sven Lotze
Infoblatt Tsunami - GFZ Potsdam

23. Thank you for your attention
Any Questions???