Deck 5: Tsunami

Question 1

In the deep ocean, tsunami waves will travel at speeds approaching ____ km/hr.

A)1
B)25
C)100
D)900
E)5,000

Answer 1

D

Question 2

The largest displacement of water from an undersea earthquake would have an amplitude of about ____ m.

A)1
B)3
C)5
D)10
E)15

Answer 2

E

Question 3

Tsunami from oceanic volcanoes are most likely to be caused by ____.

A)rising upward suddenly
B)sinking downward suddenly
C)creating heat that boils seawater
D)ejecting large amounts of gas
E)submarine volcanic explosions

Answer 3

E

Question 4

Tsunami wave motion drags on the bottom of shallow water, decreasing the wave height.

Question 5

____ caused a major tsunami wave in Alaskan coastal fjords.

A)A stratovolcano eruption
B)An undersea landslide caused by liquefaction of beach sediment
C)A massive rockfall at one end of the fjord
D)Calving of the ice at the end of a glacier
E)A submarine landslide within the fjords

Question 6

Compared to wind-driven waves, tsunami waves have ____.

A)shorter periods and higher wave speeds
B)shorter periods and lower wave speeds
C)longer periods and lower wave speeds
D)generally similar periods and wave speeds
E)longer periods and higher wave speeds

Question 7

The strength of a tsunami created by a landslide depends most heavily on the ____.

A)type of rock contained in the landslide
B)volume of material in the landslide
C)height of fall of the landslide
D)strength of the earthquake causing the landslide
E)volume of water under the landslide

Question 8

The first wave of a tsunami is rarely the highest.

Question 9

In coastal subduction zones, the oceanic plate can rise suddenly, triggering a tsunami.

Question 10

Structures can mitigate tsunami damage, but vegetation cannot.

Question 11

Which type of event is a source of tsunami danger for the northeastern U.S.?

A)A subduction-zone earthquake along the coast of Africa.
B)A subduction-zone earthquake off the coast of the northeastern U.S.
C)A transform-fault earthquake on the Mid-Atlantic Ridge.
D)Flank collapse of a volcano in Sardinia.
E)Flank collapse of a volcano in the Canary Islands.

Question 12

Someone fleeing a tsunami should be safe once they reach a point 100 m from shore and 10 m above water level.

Question 13

The effects of tsunami are amplified in bays and river mouths.

Question 14

Major tsunami from Pacific subduction zones can occur as often as every few hundred years.

Question 15

Tsunami are caused by any large, rapid displacement of water.

Question 16

Tsunami generated by asteroid impact are common. ​

Question 17

Tsunamis cannot be caused by ____.

A)hurricanes
B)landslides
C)volcanoes
D)earthquakes
E)asteroids

Question 18

A major tsunami forms somewhere in the Pacific about once every ____ years.

A)10
B)2
C)100
D)20
E)50

Question 19

____ faults do NOT typically cause tsunami waves.

A)Normal
B)Reverse
C)Blind
D)Thrust
E)Strike-slip

Question 20

Tsunami wave velocity is constant with depth, and remains the same in deep ocean and shallow water.

Question 21

If you are alerted that a tsunami is approaching, your first reaction should be to ____.

A)immediately seek protection in groves of vegetation
B)immediately head for a location as far inland as possible
C)immediately head for a location as high above sea level as possible
D)travel in an orderly safe fashion to a location as far inland as possible
E)wait for instructions from emergency personnel

Question 22

The difference between tsunami watches and tsunami warnings is that ____.

A)tsunami warnings are issued when an earthquake occurs, and watches are issued when there is less than one hour before the arrival of the tsunami
B)tsunami watches are issued when an earthquake occurs, and warnings are issued when there is less than one hour before the arrival of the tsunami
C)warnings are issued when a major earthquake happens, and watches are issued when tsunami waves are detected
D)watches are issued when a major earthquake happens, and warnings are issued when tsunami waves are detected ​
E)tsunami watches are issued when the effects will not affect populations, and warnings indicate hazards to life and property

Question 23

As the first wave of a tsunami retreats from the shore, bystanders should expect a second wave within approximately ____.

A)15 minutes
B)two minutes
C)one hour
D)twelve hours
E)two days

Question 24

The _______________ of a volcano can collapse and slump, triggering a tsunami as a debris avalanche distributes material along the seafloor.

Question 25

In a subduction zone, the descending oceanic plate may deform the continental plate, creating a(n) _______________. (two words)

Question 26

Direct evidence of giant tsunami is found in ____.

A)volcanic slump zones around Hawaiian volcanoes
B)beach erosion on Pacific islands
C)alternating layers of peat, sand, and mud containing saltwater plants
D)reverse faults along subduction zones
E)magnetic field patterns in sedimentary rock

Question 27

A ship at sea will not generally notice the passage of a tsunami wave because they ____ in the deep ocean.

A)have long periods and small wave heights
B)have long periods and high wave heights
C)have short periods and small wave heights
D)have short periods and high wave heights
E)are very similar to normal ocean waves

Question 28

Tsunami effects are increased by ____.

A)increasing water depth
B)the funneling effect of bays
C)changes in water temperature and density
D)sandbars near shore
E)hot weather

Question 29

The series of tsunami generated in a single offshore event will impact the coastline for a period of several ____.

A)minutes
B)seconds
C)days
D)weeks
E)hours

Question 30

Upon landfall, a tsunami will move ____.

A)at walking speed
B)faster than it traveled in the open ocean
C)at the speed of a helicopter or small airplane
D)much too fast for a person to outrun
E)at the speed of a commercial jet

Question 31

Tsunami detection networks are ____.

A)accurate at predicting the arrival of a nearby tsunami, but not a far-field tsunami
B)rapid enough to predict the arrival of a tsunami generated nearby in time for people to evacuate
C)inaccurate at predicting arrival times of tsunamis generated in the middle of the Pacific Ocean
D)accurate at predicting the arrival of a distant tsunami, but rarely provide sufficient warning of tsunami generated by a nearby earthquake
E)available in the Atlantic but not the Pacific Ocean

Question 32

As a tsunami enters shallow water, ____.

A)the wave speed will increase, and the height will increase
B)the wave speed will increase, and the height will decrease
C)the wave speed will decrease, and the height will decrease
D)the wave speed will decrease, and the height will increase
E)the wave speed remains the same as the height increases

Question 33

A tsunami in Japan would affect ____.

A)all coastal areas of the Pacific
B)areas within 1000 km of the epicenter
C)areas in Asia only
D)areas in Asia and the Pacific islands only
E)areas in the northern hemisphere only

Question 34

A(n) _______________ landslide occurs underwater and may cause a tsunami.

Question 35

Vegetation mitigates tsunami effects except when ____.

A)it is the form of trees, not grasses and shrubs
B)trees become uprooted and become dangerous projectiles
C)the vegetation is too close to the shore
D)it is in the form of grasses, not trees and shrubs
E)trees are not present

Question 36

Giant tsunami are usually the result of _____.

A)earthquakes only
B)landslides only
C)volcanic eruptions only
D)earthquakes, volcanic eruptions, or landslides
E)earthquakes or landslides, but not volcanic eruptions

Question 37

When a tsunami wave passes an island surrounded by shallow water, ____.

A)the effect of the tsunami will be greatest on the near side of the island, but will affect the whole island
B)the effect of the tsunami will be greatest on the far side of the island, but will affect the whole island
C)the tsunami will affect the half of the island facing the wave, but leave other areas untouched
D)the tsunami will affect the half of the island facing away from the wave, but leave other areas untouched
E)the effect of the tsunami will be spread evenly around the island

Question 38

The word _______________ is a Japanese word meaning harbor wave.

Question 39

As a tsunami enters a bay or fjord, wave height ____.

A)increases because the water depth deepens
B)increases because water is warmer
C)decreases because the water depth decreases near shore
D)increases because the wave is forced into a narrower space
E)decreases only if bay water is shallower, increases if it is deeper

Question 40

The linear distance between two wave crests is the _______________ of the tsunami.

Question 41

Explain several conditions that will change the shape and force of a tsunami as it contacts the shoreline, and the effect that each condition will potentially have.

Question 42

Evidence of past tsunami can be seen in the _______________, a line across a mountainside separating taller and shorter trees.

Question 43

Atlantic coastal regions are at risk of a giant tsunami generated by landslides in the _______________ Islands.

Question 44

You are vacationing on a beach in Thailand. List and describe four natural warning signs you might think of as evidence for a potential tsunami.

Question 45

You have taken a job in Boston, Massachusetts, a large metropolitan city at a fairly high northern latitude. The metropolitan area surrounding a wide, deep harbor facing northeast. ​ Describe what you should think about in terms of tsunami danger. Discuss the danger in terms of likelihood, strength, and comparison to other hazards you will experience in this area.

Question 46

A tsunami _______________ is issued when an earthquake of magnitude 7 or greater is detected somewhere around the Pacific Ocean.

Question 47

Discuss the process of tsunami creation from an earthquake in an offshore region of a subduction zone. What are the key factors affecting the strength of the tsunami?

Question 48

The _______________ is the height that a tsunami reaches as it rushes onshore.

Question 49

The time that it takes one complete wave to pass a fixed point is the _______________ of the wave.

Question 50

Cowell's Cove is a beach in Santa Cruz, California noted for good surfing. The Santa Cruz coastal area is in the form of a broad (5 km) short (1.5 km) bay, facing south. ​ On the west side of the beach is a long (1 km) raised peninsula with a steep rocky cliff edge. The top is about 5 m above the water level. Behind the peninsula, the ground rises in a neighborhood of twisty, one-lane streets to a level 15 m above sea level. The nearest stairway is about 100 m away. To the east, the beach is flat leading to a popular tourist boardwalk. Your car is parked behind the boardwalk about 200 m away. Behind this area a straight two-lane road goes through the downtown area for about 5 km before reaching Highway 101 and hilly country. ​ The sea is calm and flat except for a regular line of clean surf breaks surf breaks about 1 m high along the peninsula. You feel a slight jolt. Some rocks tumble from the cliffs, and you can hear car horns honking at areas along the beachfront. After looking around for a few minutes, you notice that the edge of the water is receding quickly, and hear sirens from emergency vehicles in some directions. ​ Assume that you are physically fit, and that your car is in good working order. What do you do? Explain your reasoning.