1.8 Making Waves Flashcards
When was the Tsunami in Japan and in what area
Tohuku, 2011
MME scale
9
Depth
25km off coast of Honshu Island (shallow)
Horizontal and vertical displacement
50m H
35m V
What two plates formed the subduction zone
Oceanic Pacific plate and Okhotsk micro plate
What three events causes a Tsunami
Volcanic eruption, underwater landslide or earthquake on ocean floor
Where is the hypocentre located
Benioff zone
What is the amplitude of a Tsunami in open deep water
Low
At what speed to tsunami waves radiate from epicentre
800km an hour
What happens as waves move towards shallow coastal water
They slow down due to increased friction from the seabed to 40kmh causing the wavelength to shorten as waves catch up and amplitude to increase
What is a subduction zone
When a more dense (oceanic crust) subducts under a less dense (continental) crust and the constant friction causes an eventual release of energy causing displacement
Why are melting temperatures lowered in the asthenosphere
Because of the addition of sea water into the ocean trench
What coastline shape creates largest wave height
Funnel coastline
What variables affect the intensity of the tsunami
Distance from the source
Shallowness of sea near coastline (more friction)
Extent of displacement
Depth of Benioff zone (deeper means more intense)
Coastline orientation
What is slab pull
Slab pull is the pulling force exerted by a cold, dense oceanic plate plunging into the mantle due to its own weight.
