OCE1001 CHP 8
The Pacific Tsunami Warning Center (PTWC) was established in 1946 to coordinate data from seismic waves in the Pacific Ocean and around the Pacific rim. It issues tsunami warnings to 25 Pacific rim nations when data suggest a tsunami is imminent. (T/F)
TRUE
Waves at the ocean surface are called orbital or interface waves. (T/F)
TRUE
Waves that are breaking along the shore and are forming curling crests over air pockets are called: -swells. -surf. -gravity waves. -plunging breakers. -spilling breakers.
-plunging breakers.
Wave speed is equal to: -wave height divided by period. -wavelength divided by period. -wavelength divided by fetch. -wave height divided by frequency. -wavelength divided by frequency.
-wavelength divided by period.
The speed of a deep-water wave is proportional to: -wave speed or celerity. -wavelength. -water depth. -wave height. -wave frequency
-wavelength.
Match the term or person with the appropriate phrase. deep-water wave speed (S) -wavelength/period -wave height -steepness = 1:7 -wavelength/2
-wavelength/period
You live on an island in the Pacific. An earthquake of magnitude 8.5 off the coast of Japan, 8000 km away, generates a tsunami with a wavelength of 200 km. The average water depth between your island and Japan is 4900 m. If a tsunami warning is issued for your island, how many hours will you have before the waves arrive? -8.51 hours -7.40 hours -12.34 hours -6.87 hours -10.14 hours
-10.14 hours
Calculate the speed (S) in meters per second for a deep-water wave with a wavelength (L) of 351 meters and a period (T) of 15 seconds. -42.3 m/s -8.75 m/s -23.4 m/s -0.04 m/s -547.5 m/s
-23.4 m/s
Of the following offshore ocean conditions, which one(s) would likely produce spilling breakers? -A steeply sloping rocky bottom -A gently sloping sandy bottom -Deep water adjacent to an abrupt shallow coral reef -A gently sloping rocky bottom -A steeply sloping sandy bottom
-A gently sloping sandy bottom -A gently sloping rocky bottom
What fault movement beneath the ocean is more likely to create a tsunami—vertical or a horizontal movement? -Both vertical and horizontal movements are equally likely to cause tsunamis, as they both displace water in the entire column. -A horizontal movement is more likely to cause a tsunami. This movement causes a sudden change in the entire water column. Vertical movements do not create water displacement and are unlikely to cause a tsunami. -A vertical movement is more likely to cause a tsunami. This movement causes a sudden change in the entire water column. Horizontal movements do not create water displacement.
-A vertical movement is more likely to cause a tsunami. This movement causes a sudden change in the entire water column. Horizontal movements do not create water displacement.
What results when two waves, in phase and with the same wavelength, interact? -A wave with an amplitude that is the sum of the amplitudes of the initial two waves. -A wave with an amplitude that is the multiplication of the amplitudes of the initial two waves. -A wave with an amplitude that is the larger of the amplitudes of the initial two waves. -A wave with an amplitude that is the difference between the amplitudes of the initial two waves.
-A wave with an amplitude that is the sum of the amplitudes of the initial two waves.
Why are internal waves usually associated with a pycnocline? -Because marine life is concentrated along the pycnocline. -Because a pycnocline always occurs near the ocean floor, even in deep water. -Because after an earthquake on the sea floor, a pycnocline is transmitted vertically from the deep ocean floor to the surface. -Because a pycnocline always occurs at the ocean surface. -Because a pycnocline is a boundary between two different water masses with different densities.
-Because a pycnocline is a boundary between two different water masses with different densities.
Why are these types of waves called internal waves? -Because they experience internal combustion. -Because they have internal energy. -Because they are internal to the ocean. -Because they have internal capabilities.
-Because they are internal to the ocean.
Why does the wave height of a tsunami increase as the tsunami enters shallow water? -In shallow water, the wind driving the tsunami must push a larger water column. -In shallow water, the energy of the tsunami must be contained within a larger water column. -In shallow water, the energy of the tsunami must be contained within a smaller water column. -In shallow water, the wind driving the tsunami must push a smaller water column.
-In shallow water, the energy of the tsunami must be contained within a smaller water column.
Besides where each type of wave is located, what is one of the most obvious physical differences between internal waves and surface waves? -Internal waves are so deep in the ocean that they can't be measured. -Internal waves only occur during very special conditions. -Internal waves can only be measured by submarines. -Internal waves have a much longer wavelength as compared to the shorter wavelength surface waves. -Internal waves are invisible while surface waves are not.
-Internal waves have a much longer wavelength as compared to the shorter wavelength surface waves.
What occurs more often, pure destructive, pure constructive, or mixed interference? -Mixed interference -Pure destructive interference -Pure constructive interference
-Mixed interference
Of the following statements about ocean waves, which is/are true? -Ocean waves can be described by their period, wavelength, and height. -Ocean waves can be classified by the depth of water in which they move. -Ocean waves involve the transport of water across ocean basins. -The only ocean waves occur along the air/water interface. -Ocean waves can be classified by the way in which they form.
-Ocean waves can be described by their period, wavelength, and height. -Ocean waves can be classified by the depth of water in which they move. -Ocean waves can be classified by the way in which they form.
Which ocean is associated with most tsunamis? -Arctic Ocean -Atlantic Ocean -Pacific Ocean -Indian Ocean
-Pacific Ocean
Which of the following best describes how scientists help the public prepare for an earthquake event? -Scientists can predict when earthquakes will happen and alert the public because there are many precursors and signs that an earthquake is about to occur. -Scientists cannot predict when exactly an earthquake will occur, but they can identify tectonically active areas that are likely to produce earthquake activity and let the public know they are in an earthquake-prone area. -Scientists have no idea what areas might experience earthquakes in the future, so there is no way to help the public prepare.
-Scientists cannot predict when exactly an earthquake will occur, but they can identify tectonically active areas that are likely to produce earthquake activity and let the public know they are in an earthquake-prone area.
When will perfect destructive interference occur? -When two waves that are 180 degrees out-of-phase interfere. -When two waves that have low amplitude interfere. -When two waves that are in-phase interfere. -When two waves that have long wavelength interfere.
-When two waves that are 180 degrees out-of-phase interfere.
Which of the following are names for large ocean waves that can be created by constructive interference? Choose all that apply. -Superwaves -Freak waves -Havoc waves -Shipwrecker waves -Rogue waves
-Superwaves -Freak waves -Rogue waves
What are the beach slope and energy characteristics of surging breakers? -Surging breakers occur on moderate to steeply sloped beaches. When breaking it has a curling motion where the crest "outruns" the rest of the wave. -Surging breakers occur on gently sloped beaches. This gentle slope change results in a gradual release of energy. -Surging breakers occur on moderate to steep slopes. The energy is compressed and is released gradually as the water moves up the shoreline. -Surging breakers occur where there is an abrupt slope change. The result is a gradual release of energy as the wave approaches the shore. -Surging breakers occur where the ocean bottom has an abrupt slope change. This results in wave energy being compressed in a shorter distance.
-Surging breakers occur where the ocean bottom has an abrupt slope change. This results in wave energy being compressed in a shorter distance.
What is a swell? -Swells are long-crested, uniform, symmetrical waves that require very little energy to travel out of their area of origin. -Swells are massive, solitary, spontaneous ocean waves that occur when ocean waves are not unusually large. -Swells are a type of breaking wave that forms on a gently sloping beach. -Swells are fast-moving gravity currents along an ocean slope (bottom) that are a mix of sediment and water. -Swells are steep, short-crested waves that require a great deal of energy to move from their place of origin.
-Swells are long-crested, uniform, symmetrical waves that require very little energy to travel out of their area of origin.
What is the relationship between wave base and wavelength? -The depth of the wave base is one-and-a-half times the wavelength of the waves. -The depth of the wave base is one-half the wavelength of the waves. -The depth of the wave base is two-thirds the wavelength of the waves. -The depth of the wave base is twice the wavelength of the waves. -The depth of the wave base is three-quarters of the wavelength of the waves.
-The depth of the wave base is one-half the wavelength of the waves.
Why does wave height increase as waves enter shallow water? -The wavelength of the wave must be contained within a larger water column in shallow water. -The energy of the wave must be contained within a smaller water column in shallow water. -The energy of the wave must be contained within a larger water column in shallow water. -The wavelength of the wave must be contained within a smaller water column in shallow water.
-The energy of the wave must be contained within a smaller water column in shallow water.
Of the following statements about ocean waves, which one(s) describe wave period? -The vertical distance between a wave crest and an adjacent trough -The inverse of wave frequency -The time it takes for one full wavelength to pass a given point -The horizontal distance between adjacent wave crests -Wave height divided by wavelength -The number of waves that pass a given point in a certain amount of time
-The inverse of wave frequency -The time it takes for one full wavelength to pass a given point
During a visit to the beach, you get in a small rubber raft and paddle out beyond the surf zone. Tiring, you stop and take a rest. Describe the movement of your raft beyond the surf zone. Select all that apply. -The raft moves in a circle, and it returns to essentially the same place. -The raft's net movement is not toward the shore compared to the surf zone. -The raft moves up and down vigorously due to the breaking of taller waves compared to the surf zone. -The raft will move toward shore along with the water particles underneath.
-The raft moves in a circle, and it returns to essentially the same place. -The raft's net movement is not toward the shore compared to the surf zone.
Which source represents 32% of renewables? -geothermal -solar -wind -tide -none of them
-none of them
Of the following statements about tsunami, which is/are true? -Tsunami always express themselves at the coast as a single rapid surge of water towards the shore. -The tsunami warning system uses seismic waves and deep-ocean pressure sensors to detect tsunami. -Tsunami have a very long wavelength, so they travel at very high speeds (equivalent to the speed of a jet airplane). -Tsunami are undetectable by ships in the open ocean. -If you are at a beach and the water suddenly drains out away from shore, it is safe to go explore the newly exposed land. -At the coast, a tsunami looks like a suddenly occurring high or low tide, which is why they are misnamed "tidal waves."
-The tsunami warning system uses seismic waves and deep-ocean pressure sensors to detect tsunami. -Tsunami have a very long wavelength, so they travel at very high speeds (equivalent to the speed of a jet airplane). -Tsunami are undetectable by ships in the open ocean. -At the coast, a tsunami looks like a suddenly occurring high or low tide, which is why they are misnamed "tidal waves."
What is an interference pattern? -The wave pattern produced when two or more waves interact. -The wavelength produced when a new wave is created. -The wavelength produced when two or more waves interact. -The wave pattern produced when a new wave is created.
-The wave pattern produced when two or more waves interact.
Why do ocean waves bend around headlands? -The waves have longer wavelength just in front of the headland, causing the waves to bend. -The waves have shorter wavelength just in front of the headland, causing the waves to bend. -The waves are moving more slowly just in front of the headland, causing the waves to bend. -The waves are moving faster just in front of the headland, causing the waves to bend.
-The waves are moving more slowly just in front of the headland, causing the waves to bend.
Assuming that renewable energy sources will contribute more and more to power generation in the future, do you expect the growth rates for these renewable energy sources to increase or decrease over the next 30-year period (2000 to 2030)? -These growth rates will likely stay the same or grow as interest in renewables increases. -These growth rates are relative to small absolute numbers. They will most likely decrease as the total contribution by renewables increases.
-These growth rates are relative to small absolute numbers. They will most likely decrease as the total contribution by renewables increases.
Will Sumatra experience another tsunami like the destructive one of December 2004? -This is unlikely, because Sumatra is in the Pacific Ocean. -This is likely, because Sumatra is in the Pacific Ocean. -This is likely, because Sumatra is near many ocean trenches. -This is unlikely, because Sumatra is near many ocean trenches.
-This is likely, because Sumatra is near many ocean trenches.
Why do ships at sea tend not to notice tsunamis? -Tsunamis in deep water have small wave height and long wavelength. -Tsunamis in deep water have small wave height and short wavelength. -Tsunamis in deep water have large wave height and long wavelength. -Tsunamis in deep water have large wave height and short wavelength.
-Tsunamis in deep water have small wave height and long wavelength.
Based on the equations for determining the speed of shallow-water waves, which one of the following variables is necessary to determine the speed of shallow-water waves? Select only one answer. -Wave height -Period -Water depth -Wavelength -It is impossible to determine the speed of shallow-water waves without more information.
-Water depth
How does water move as waves pass? -Water moves in a circle in the same direction as wave movement. -Water moves in a circle in the direction opposite to wave movement. -Water moves linearly in the opposite direction to wave movement. -Water moves linearly in the same direction as wave movement.
-Water moves in a circle in the same direction as wave movement.
with depth in water? -Wave amplitude decreases as depth increases. -Wave amplitude increases as depth increases. -Wave amplitude remains the same as depth increases.
-Wave amplitude decreases as depth increases.
Which of the following statements about wave period is most accurate? -Wave period is the inverse of wave height. -Wave period is the inverse of wavelength. -Wave period is the inverse of wave amplitude. -Wave period is the inverse of wave frequency.
-Wave period is the inverse of wave frequency.
How does wave refraction at headlands affect deposition and erosion? -Wave refraction at the headland increases deposition at the headland and causes erosion in adjacent bays. -Wave refraction at the headland decreases erosion at the headland and causes deposition in adjacent bays. -Wave refraction at the headland increases erosion at the headland and causes deposition in adjacent bays. -Wave refraction at the headland decreases deposition at the headland and causes erosion in adjacent bays.
-Wave refraction at the headland increases erosion at the headland and causes deposition in adjacent bays.
What does the term "in phase" refer to? -Waves in phase have different wavelengths and are aligned peak-to-peak and trough-to-trough -Waves in phase have different wavelengths and are aligned peak-to-trough and trough-to-peak -Waves in phase have identical wavelengths and are aligned peak-to-trough and trough-to-peak -Waves in phase have identical wavelengths and are aligned peak-to-peak and trough-to-trough
-Waves in phase have identical wavelengths and are aligned peak-to-peak and trough-to-trough
While you are playing Frisbee in the surf zone with another person, your friend watches while sitting on the beach nearby. After a while, you look up at the beach and realize you are no longer directly in front of your friend, who remained stationary on the beach all the while—you are still in the surf zone, but 30-40 yards from where you started. What is the correct reason for this movement? -One person must have continually overshot the Frisbee to move them further out to sea. -The beach moved opposite the angle of the waves. -Waves were coming in to the shore straight on so the current carried you upstream. -Waves were coming at the shore at an angle. The longshore current moved downstream to that angle and pushed the Frisbee players that direction.
-Waves were coming at the shore at an angle. The longshore current moved downstream to that angle and pushed the Frisbee players that direction.
How are wave period and wavelength related? -Waves with shorter periods have shorter wavelengths. -Waves with longer periods have shorter wavelengths. -Waves with shorter periods have longer wavelengths.
-Waves with shorter periods have shorter wavelengths.
When will perfect constructive interference occur for waves that are in phase and moving at the same velocity? -When waves with identical wavelengths interfere. -When waves with large amplitudes interfere. -When waves with short wavelengths interfere. -When waves with identical amplitudes interfere.
-When waves with identical wavelengths interfere.
What common office item is used in this video to demonstrate internal waves? -a stapler -a tape dispenser -a pair of scissors -a paper clip -a desktop ocean
-a desktop ocean
What is a tsunami? -a series of water waves that travel away from a fault in all directions at low speed -a series of water waves that travel toward a fault in all directions at high speed -a series of water waves that travel away from a fault in all directions at high speed -a series of water waves that travel toward a fault in all directions at low speed
-a series of water waves that travel away from a fault in all directions at high speed
By how much would solar have to grow to match the current level of hydroelectric power? -about 2 times -about 10 times -about 60 times -about 100 times
-about 60 times
Where are internal waves most likely to form? -along areas of rapidly changing temperature in the water column, such as the air-water interface -in areas near coastal glaciers where large icebergs fall into the ocean -in the nearshore environment where waves begin to "feel" the bottom -along areas of rapidly changing density, such as a pycnocline
-along areas of rapidly changing density, such as a pycnocline
An internal wave might form: -at the boundary between the atmosphere and the ocean. -at the boundary between the ocean and the seafloor. -close to shore as it moves into shallow water. -at a density boundary within the ocean. -only as a result of tidal activity.
-at a density boundary within the ocean.
Assume depletion of nonrenewables requires renewables (excluding combustibles and waste) to account for more than 30% by 2040. What growth rates of renewables must be achieved and by when? -1% annual growth rate -10% annual growth rate -at least 15% annual growth rate -Current growth rates are sufficient to meet this goal.
-at least 15% annual growth rate
The first wave that forms when the wind begins to blow across the ocean surface is a: -tsunami. -reflected wave. -seiche. -capillary wave. -tide.
-capillary wave.
What type of plate boundary are most tsunamis associated with? -convergent plate boundaries -divergent plate boundaries -transform plate boundaries
-convergent plate boundaries
The height of a wave depends upon: -fetch. -fetch and wind speed. -fetch, wind duration, and wind speed. -wind duration. -wind duration and wind speed.
-fetch, wind duration, and wind speed.
As a wave begins to feel bottom near a shoreline, its wave height: -increases and its wavelength decreases -increases and its wavelength remains the same. -increases and its frequency decreases. -decreases and its steepness decreases. -decreases and its wavelength increases.
-increases and its wavelength decreases
A disadvantage shared by wave, solar and wind energy is that __________. -it is not available on demand, and there currently is no viable way to store the energy -the power produced must be transmitted long distances from where it is produced to where it is consumed -governments are unwilling to subsidize renewable forms of energy -the energy tends to be concentrated in areas of high latitude and is not readily available to tropical countries -installations must be protected from the very energy that they collect
-it is not available on demand, and there currently is no viable way to store the energy
Match the term with the appropriate phrase. atmospheric waves -movement of air across the air-water interface -the energy that causes ocean waves to form -movement of different air masses along an air-air interface -movement of water of different densities along a water-water interface -waves at the ocean surface involving longitudinal and transverse waves
-movement of different air masses along an air-air interface
Submarines sometimes ride out heavy storms in deep water by submerging. That is a practical application of utilizing the ____________________. -wave refraction in deep water -principle of decreasing orbital motion with depth -principle of constant proportions -SOFAR channel for safe navigation -thermohaline stratification
-principle of decreasing orbital motion with depth
Which projection has nonrenewables comprising roughly 50% of our energy production in 2050? -projection 1 -projection 2 -both projections -neither projection
-projection 2
Destructive wave interference results in ___________. -increased beach erosion -rogue waves -reduced wave height -intensified surface currents -the very best breakers for surfing
-reduced wave height
A tsunami is considered to be a: -capillary wave. -deep-water wave. -reflected wave. -shallow water wave. -refracted wave.
-shallow water wave.
Constructive interference results in larger waves whereas destructive interference produces: -capillary waves. -swells. -rouge waves. -smaller waves. -tsunamis.
-smaller waves.
Which energy source's annual growth rate is about four times greater than that of tidal power? -geothermal -solar -wind -none of the above
-solar
Match the term or person with the appropriate phrase. ratio of wave height to wavelength at which waves break -wavelength/period -wavelength/2 -steepness = 1:7 -wave height
-steepness = 1:7
What is refraction? -the bending of waves due to a change in wave amplitude -the bending of waves due to a change in wave phase -the bending of waves due to a change in wave velocity -the bending of waves due to a change in wavelength
-the bending of waves due to a change in wave velocity
What is the wavelength? -the distance between the highest and lowest part of the wave -the lowest part of the wave -the highest part of the wave -the time it takes for one wavelength of a wave to pass a particular point -the distance between consecutive wave crests or troughs
-the distance between consecutive wave crests or troughs
What is the wave height? -the distance between the highest and lowest part of the wave -the highest part of the wave -the lowest part of the wave -the distance between consecutive wave crests or troughs -the time it takes for one wavelength of a wave to pass a particular point
-the distance between the highest and lowest part of the wave
Match the term with the appropriate phrase. disturbing force -the energy that causes ocean waves to form -waves at the ocean surface involving longitudinal and transverse waves -movement of different air masses along an air-air interface -movement of air across the air-water interface -movement of water of different densities along a water-water interface
-the energy that causes ocean waves to form
What is the crest of a wave? -the distance between consecutive wave crests or troughs -the time it takes for one wavelength of a wave to pass a particular point -the lowest part of the wave -the highest part of the wave -the distance between the highest and lowest part of the wave
-the highest part of the wave
What is the wave base? -the upper limit of wave-induced motion in the water -the lower limit of wave-induced motion in the water -the furthest distance a wave can get to shore before dissipating -the closest distance a wave can get to shore before breaking
-the lower limit of wave-induced motion in the water
What is the trough of a wave? -the distance between the highest and lowest part of the wave -the highest part of the wave -the distance between consecutive wave crests or troughs -the time it takes for one wavelength of a wave to pass a particular point -the lowest part of the wave
-the lowest part of the wave
What is the wave period? -the distance between consecutive wave crests or troughs -the time it takes for one wavelength of a wave to pass a particular point -the distance between the highest and lowest part of the wave -the highest part of the wave -the lowest part of the wave
-the time it takes for one wavelength of a wave to pass a particular point
How are tsunamis generated? -through creation of the seafloor under water -through creation of the seafloor above water -through displacement of the seafloor above water -through displacement of the seafloor under water
-through displacement of the seafloor under water
Match the term or person with the appropriate phrase. diameter of orbital wave at the surface -wave height -steepness = 1:7 -wavelength/2 -wavelength/period
-wave height
The diameter of a wave orbital at the surface is equal to: -wavelength/wave period. -wave height/wavelength. -wave height. -wave period. -wavelength.
-wave height.
Standing waves may be caused by: -destructive interference. -wave diffraction. -wave refraction -constructive interference. -wave reflection.
-wave reflection.
Waves converge on headlands due to: -constructive interference. -destructive interference. -wave refraction. -wave reflection. -wave diffraction.
-wave refraction.
The ratio of wave height to wavelength is called the: -frequency. -period. -wave height. -wave steepness. -wavelength.
-wave steepness.
Waves usually arrive nearly parallel to the shore because _______________. -waves are refracted toward deep water -waves destructively interfere with each other -waves are refracted toward shallow water -most waves come from storms that are directly offshore -waves constructively interfere with each other
-waves are refracted toward shallow water
The largest wind-generated waves tend to be associated with the: -polar regions. -trade winds. -equatorial doldrums. -horse latitudes. -westerlies.
-westerlies.
Worldwide, where are the best locations for new wave farms? -windward, western shores in areas that are particularly stormy and produce large waves -windward western shores that have weak currents and small wave heights -equatorial regions that have high winds and small waves -very high latitudes (greater than 60∘) in polar regions -eastern shores in areas that have broad continental shelves
-windward, western shores in areas that are particularly stormy and produce large waves
Please identify the word and/or phrase that does NOT fit the pattern. A. crest B. height C. length D. period E. trough
D. period
Please identify the word and/or phrase that does NOT fit the pattern. A. plunging breaker B. spilling breaker C. surf D. surging breaker E. swell
E. swell
A shallow-water wave must form in water depth less than 100 meters. (T/F)
FALSE
Rogue waves are generated by destructive interference patterns of ocean swells. (T/F)
FALSE
The horizontal distance between two successive troughs is called the wave height. (T/F)
FALSE
Tsunami travel as deep-water waves over the open ocean. (T/F)
FALSE
A curling wave formed over an air pocket is called a plunging breaker. (T/F)
TRUE
A standing wave can be caused by wave reflection. (T/F)
TRUE
A wave train is caused by wave energy moving more slowly than individual waves. (T/F)
TRUE
Deep-water waves move faster than shallow water waves because they are not slowed by friction with the ocean bottom. (T/F)
TRUE