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TsuNami Earth Science & Physics Learning Standards Earth Science: – Major Understandings: Physics: – Major Understandings: 4.3b, 4.3c, 4.3e Waves

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Tsu Nami

Tsunami

Earth Science & Physics

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

Types of Waves

• There are two types of waves

– Longitudinal

– Transverse

Anatomy of a Wave

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

Wave Frequency

• Frequency measures how many cycles a waves completes in one second (Hertz)

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?

dgV

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