1. Physics of Tsunamis Part 1: Introduction to Waves

2. Tsunami Animation

3. How are tsunamis created?
Causes: earthquakes, landslides, volcanic eruptions, meteorites and nuclear tests.
Tsunamis are water waves that form in the ocean where depths of water average 4km.
In order to understand physics of tsunamis we will begin by understanding the basic concepts of waves.

4. What are waves?
Waves are caused by vibrating objects; example: guitar string, throwing a rock in the water.
Water waves are combination of two types of waves:
Transverse waves
Longitudinal waves

5. Check your understanding
Q: A transverse wave is transporting energy from east to west. The particles of the medium will move_____.
east to west only
both eastward and westward
north to south only
both northward and southward
Answer: D
The particles would be moving back and forth in a direction perpendicular to energy transport. The waves are moving westward, so the particles move northward and southward

6. Check your understanding
Q: Describe how the fans in a stadium must move in order to produce a longitudinal stadium wave.
Answer:
The fans will need to sway side to side. Thus, as the wave travels around the stadium they would be moving parallel to its direction of motion. If they rise up and sit down, then they would be creating a transverse wave

7. Water Waves
Water waves are combination of transverse waves and longitudinal waves. Therefore, water molecules move in elliptical pattern (Example: floating objects).

8. Wave Features Wave Height (amplitude)
Time Period, T & Frequency, f : T=1/f [s=1/Hz]
Wavelength, m
Speed, v: v=/T [m/s]

9. Check your understanding
Q: As the frequency of a wave increases, the period of the wave ___________.
Decreases
Increases
Remains the same
Answer: A
Period is the reciprocal of the frequency. So as f increases, 1 / f decreases

10. Check your understanding
Q: The water waves below are traveling along the surface of the ocean at a speed of 2.5 m/s and splashing periodically against Wilbert's perch. Each adjacent crest is 5 meters apart. The crests splash Wilbert's feet upon reaching his perch. How much time passes between each successive drenching?
Answer:
If the wave travels 2.5 meters in one second then it will travel 5.0 meters in 2.0 seconds. If Wilbert gets drenched every time the wave has traveled 5.0 meters, then he will get drenched every 2.0 seconds.

11. Transfer of Energy