Tsunami Notes
Tsunami
What is a Tsunami?
- Big waves that travel at great speed.
- Also called seismic sea waves or tidal waves.
- Japanese word meaning "harbour wave".
- Series of fast-moving, long period waves generated by large disturbances below or near the seafloor.
- Can travel up to 800 km/hour.
- Typical wind wave period = 6 – 12 seconds vs. Tsunami wave period = 15 – 60 minutes.
- Caused by the displacement of large volumes of water.
- Displacement caused by earthquakes, landslides, volcanic eruptions, or meteorites.
- Most commonly caused by submarine earthquakes.
Tsunami Characteristics
- Wave period: 15-60 minutes
- Wavelength: Up to 500 km in the deep ocean
- Wave velocity: > 500 km/hour in deep water
- Wave height: < 0.5 m in deep water
Impact of Tsunamis
- Short term impacts include infrastructure damage, deaths, displacement, and loss of food and water.
- Long term impacts include environmental, food, water, communication, health, economic, and social issues.
Examples of Tsunamis
- 2004 Boxing Day Tsunami: Magnitude 9.3 earthquake off the coast of Sumatra.
- 2011 Tsunami in Japan.
- 1960 Great Chilean Earthquake: Measured 9.5 on the Richter Scale, generating a destructive tsunami.
Reducing Tsunami Risk
- Tsunami Warning Systems: Detect seismological changes and provide warnings.
- Indian Ocean Tsunami Warning System: Established after the 2004 tsunami.
- Civil defence authorities provide guidelines on how to react in case of a tsunami.
Key points
- Fast moving long period waves.
- Caused by displacement of water, particularly by earthquakes.
- Significant short and long term impacts on people and places.