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- 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. CLICK HERE
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
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 D c. A to G d. C to G
Wave Frequency Frequency measures how many cycles a waves completes in one second (Hertz)
Period – Frequency Relationship 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?
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