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

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

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 300.000 people

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

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

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

3. Physical Background 3.1 Formation of tsunamis

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

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

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

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

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

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

3. Physical Background 3.6 Striking coast

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

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

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

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

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

6. Sources Solitonen in Natur und Technik - Sven Lotze Infoblatt Tsunami - GFZ Potsdam http://www.tsunami.noaa.gov/tsunami_story.html www.wikipedia.org http://www.naturgefahren.de/tsunami.htm

Thank you for your attention Any Questions???