TSUNAMI EXPERIMENT

KEY CONCEPTS

  1. A tsunami is an open ocean wave that is generated by a sudden displacement of the sea floor. Tsunami is the Japanese word for "harbor wave." (Sometimes tsunamis are called "tidal waves," which is incorrect as they have nothing to do with tides).
  2. The wavelengths of tsunamis typically exceed 200 kilometers.
  3. The energy generated by the sudden displacement of the sea floor transmits through the water. In deep oceans, the seismic waves are unnoticeable until the energy of the wave reaches the shallow waters of the coastlines.
  4. When a tsunami approaches shallow water, it can reach as high as 100 feet or more.
 

MATERIALS

  • plastic cake pan
  • 16 oz. water or Rheoscopic fluid
  • scissors
  • sturdy plastic wrap
  • tape
  • "Physics of the Wave" chart (provided below)
  • (optional) QuickTime animation viewer installed on your computer
 
 

PROCEDURE

  
 
 

Activity

  1. Cut a hole in the bottom of the plastic cake pan approximately 4 inches in diameter.
  2. Tape plastic wrap on the outside of the plan covering the hole, making sure it is water tight.
  3. Fill pan with fluid.
  4. Gently tap on the plastic wrap on the bottom. What happens? Why?
  5. Change the strength of your tap. What happens?
  6. Click here to see an animation of a tsunami.
 
 

Discussion questions

  • How fast can tsunamis travel?
  • What are typical tsunami wave lengths and wave periods?
    • Click here to see an image of wave length and wave period.
  • What causes tsunamis?
  • As wave length increases, what happens to wave velocity?
  • Imagine that you live in a coastal community that is susceptible to tsunamis. What should your community do to mimimize the potential impact and loss of life?
  
 
 

CROSS-CURRICULAR IDEAS

  • Mathematics:
    • Speed of propagation is V = square-root of (g * h)
      • V is the velocity in meters per second
      • g is the acceleration of gravity, 9.8 meters per (second)^2
      • h is water depth in meters
    • If the wave depth is 3000 meters, what is the velocity?
    • If the water depth is only 50 meters, what is the velocity?
      • Is this faster or slower than a deep water wave?
    • If the velocity is 15 meters per second, what is the depth of the water?
 
 

VOCABULARY

  • velocity: speed or the rate of action.
  • wave length: is the distance between two successive wave crests
  • wave period: is the time it takes two wave crests to pass a fixed point.
  
 

SOURCE

  • Adapted from 1998 "Project Oceanography" Spring Series, Copyright, University of South Florida Distance and Technology Mediated Learning
 
Physics of wind-generated waves, tsunamis in the deep ocean, and tsunamis approaching shore.