How Tsunamis Form

Name: _________________________________       Date: _____________

The Indonesian earthquake of 2004 spawned the most destructive tsunami in history, killing over 230,000 people. How do earthquakes trigger tsunamis? Can people be warned in time when one is on the way? You'll explore these questions in this activity.

  1. View a NOAA Animation of the spread of the tsunami of December 26, 2004. Describe how it spread from the epicenter.
  2. Visit the USGS Life of a Tsunami. Read Initiation Look at the sea floor diagram. What happens on the sea floor during an underwater earthquake?
  3. Scroll to Split. Describe the two parts of a tsunami split.
  4. Continue to Amplification. How do the amplitude and wavelength of a tsunami change when it reaches a continental slope?
  5. Read Run up. How is a tsunami wave different from normal waves at the beach?
  6. What causes most of the damage from a tsunami?
  7. Explain why it's not safe to return to a beach for several hours after the first tsunami run up.
  8. The Indonesian tsunami would have been much less deadly if a warning system had been in place. View this DART system animation, then read the description. Describe how the warning system works.