What is a tsunami?
A series of larger than average waves
What are tsunamis usually caused by?
Submarine earthquakes or volcanic eruptions.
Where do tsunamis usually occur?
Along plate boundaries since they are linked to tectonic activities.
5 steps of tsunami formation
- Displacement of large area of the sea floor; usually by an uplifted fault block or rebounding crust at convergent boundaries.
- Sea floor uplift displaces water column.
- Waves radiate from the source in all directions. Wavelength is very long but wave height is low.
- Waves slow down as they reach the coast due to friction from the increasingly shallow sea floor. Wave length decreases and height increases as water crowds into a smaller area.
- Four to five waves arrive over several hours; 40% of wave energy is scattered back to sea; 60% of energy used at the coast.
What is a water column?
The area of seawater from the surface to the sea floor.
Why are tsunami difficult to detect in deep ocean?
Tsunamis are difficult to detect by ship because of their long wave length and short wave height.
What physical factors affect the severity of the tsunami?
Cause of the wave e.g eruption or earthquake
Distance traveled from the source, as energy is lost as they travel.
Water depth over route affects energy due to friction.
Offshore topography and coastline orientation.
What does DART stand for?
Deep ocean assessment and reporting of tsunamis
What is DART
Attempts to detect tsunamis by using buoys to detect wavelength and wave height.
