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Learning Standards• Earth Science:
– Major Understandings:
• Physics:– Major Understandings: 4.3b, 4.3c, 4.3e
• Waves transfer energy• There are two types of waves• Waves contain an amplitude, wavelength, period, and
frequency
Tsunami• Tsunami- in Japanese means “harbor wave”
What is a commonly misused name for Tsunami?
TIDAL WAVE
What is a Tsunami?
• Tsunami- is a series of very long wavelength ocean waves generated by the sudden displacement of large volumes of water.
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What causes a Tsunami
• Undersea earthquakes• Landslides• Volcanic eruptions• Extra-terrestrial impacts
Characteristics of Waves
• Waves are a pattern of rising and falling water level, transmitted along the surface
• Ocean waves are a transport of energy, not water
Difference between wind waves and a Tsunami
• Wind waves travel only on the surface of the water
• Tsunami waves cause the entire column of water, from the surface to ocean floor, to rise and fall
Lets Check Your Understanding!
• 1. The wavelength of the wave in the diagram above is given by letter ______.
• 2. The amplitude of the wave in the diagram above is given by letter _____.
One more!
Indicate the interval that represents one full wavelength. a. A to C b. B to Dc. A to Gd. C to G
Period – FrequencyRelationship
• A wave’s period refers to the amount of time it takes for two successive wave crests to pass a given point.
• A wave’s period and frequency are Inversely proportional.
Check for Understanding, Part 2!
• A wave has an amplitude of 3.8 cm, a frequency of 51.2Hz and a wavelength of 24.8 cm. Determine its/ period.
• A fly flaps its wings back and forth 121 times each second. What is the period of its wings?
• As the frequency of a wave increases, the period of the wave______________.
Velocity of a Wave
• Velocity = Wavelength / Period
• Velocity = Wavelength * Frequency
Ex.) Find the velocity of a 20 Hz wave that has a 5 meter wavelength.– F= 20 Hz, Wavelength= 5m, Velocity=?– Velocity= (20 Hz)*(5 m) = 100 m/s
The Physics behind a Tsunami
• Due to large wavelengths (+500km), tsunamis are considered shallow water waves.
• The velocity of a shallow water wave differs from the velocity of a regular wave.
• If we use a depth of 4000m, what would the velocity of the wave be?
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What happens when a Tsunami nears land?
• As water depth decreases, the Tsunami’s velocity decreases
• Shallower water would increase the height of the Tsunami
What happens when a Tsunami reaches land?
• Flooding• Mass destruction and erosion• Large death-tolls
Warning Signs
• Earthquakes- not all earthquakes will cause a tsunami, but better safe than sorry
• Sea retreat- a tsunami will cause a rapid retreat and exposed large amounts of the ocean floor
• Sound- a approaching tsunami will sound like a train or even a jet
• http://blog.shockwave.com/wp-content/uploads/2010/04/earth1.gif
• http://www.blackcoraldivers.org/Content/images/Underwater_Background_by_Linzee777.jpg
• http://www.superchefblog.com/images/tsunami_japanese.png
• http://archivos.metatube.com/uploads/gallery/pics/gallery_pic_1612_19391.jpg