Lecture #3 Flashcards
What does Tsunami mean in Japanese?
Harbour wave
How are tsunamis produced?
By the sudden displacement of water
What are the 2 ways in which earthquakes can cause tsunamis?
- Displacement of sea floor
- Triggering landslides which fall into the water
What magnitude of an earthquakes is required to produce a tsunami event as well?
7.5M
What is the 1st stage of tsunami development?
Displacement of the seafloor pushes the water up and when it hits the surface it spreads outward
What is the 2nd stage of tsunami development?
Waves move rapidly across the open ocean, but are asmall
-spacing between waves in large
What is the 3rd stage of tsunami development?
As the tsunami approaches land the water depth decreased
-causes the water to pile up and decrease wave speed, decrease in spacing of the waves and an increase in wave amplitude
What is the 4th stage of tsunami development?
As the tsunami hits land, waves get taller
-wave speeds up
What is a run up?
The max horizontal and vertical distances that the largest waves of tsunami reaches as it travels inland
-basically describes the geographic area impacted by a tsunami
What is a distant tsunami?
Also called tele-tsunamis
- Travels thousands of kilometres across the open ocean
- has a lessened impact
what its a local tsunami?
A tsunami that affects shorlines a few kilometres to about 100 km from its source
Which areas are at a greater risk of being affected by tsunamis?
- coasts located near or across the ocean from subduction zones
- Pacific ocean
- Mediterranean sea
What are primary effects of tsunamis?
Floodin+ erosion destroys vegetation adn infrastructure
How do most deaths occur from tsunamis?
Drowning
What are secondary effects of tsunamis?
These effects generally occur after the event is over
-fires, contaminated water
What are the natural service functions of tsunamis?
-Carry fertile sediment onto the land that can then be used for agriculture
When did the Indian Ocean Tsunami of 2004 happen? What was the magnitude of the earthquake that caused it?
December 26th
9.1M
Where did the Indian ocean tsunami occur?
At subduction zone between burma and indo-australian plate
-3rd strongest quake in world history
How many and why did so many people die?
230,000
because they didn’t have a proper warning system in place in the pacific ocean
-people weren’t familiar with tsunamis and ignored the warning signs
Why isn’t a warning system enough?
Need an evacuation plan
tsunami education is also needed
How do you detect tsunamis?
Seismographs are connected to buoys that verify if a tsunami was produced from the quake.
What are Tsunameters?
Sensors that rest on the sea floor and measure changes in water pressure paling over them
What are some structural controls for tsunamis?
- better building regulations
- levees
- off shore barriers
What are inundation maps?
Shows the run up of previous tsunamis which help to plan for future events