Chapter #6

Question 1

Tsunami Tigger’s include,

Answer 1

• Earthquakes
• Landslides
• Explosive volcanic eruptions
• Meteorite impacts

Question 2

How are Tsunami’s generated?

Answer 2

The sudden movement of a large mass against the sea surface.

These masses include:
* the seafloor shifting up or down
* a submarine and/or subaerial landslide
* a pyroclastic flow
* an air blast from an explosive volcanic eruption
* a meteorite impact

Question 3

Tsunamis are not _____

Answer 3

Tsunamis are not tidal waves or large storm waves

Question 4

What creates the multiple waves in a Tsunami?

Answer 4

The equilibrium of the water is disrupted, either pushing water up or down, then the gravitational force attempts to restore equilibrium forming multiple waves.

Question 5

Trough (Tsunami)

Answer 5

The line along which water depth is at it’s lowest

Question 6

Crest (Tsunami)

Answer 6

The line along which water depth is at it’s highest

Question 7

Tsunami wave characteristics depend on 3 variables, these are

Answer 7

1. The area over which the generating mass moves
2. The amount of movement
3. The velocity of movement

Question 8

Class Question #1
Why are tsunamis classified as gravity waves?

a) Gravity causes the seafloor to suddenly rise, pushing up the water’s
surface.

b) Gravity acts as a restoring force that returns water to its equilibrium
level.

c) Gravity differences between the seafloor and continental rock
create very high tsunami waves.

d) Gravity increases the complexity of tsunami waves as they
propagate across open oceans.

Answer 8

b) Gravity acts as a restoring force that returns water to its
equilibrium level. (correct answer)

Question 9

Tsunami height variables include,

Answer 9

• The distance between source and location
• The amount of water pushed by mass
• The shape and velocity of the mass pushing the water
• wave reflection, refraction, and interference

Question 10

Are tsunami waves faster near the shore or open sea?

Answer 10

They are faster at open sea

Question 11

Velocity of Tsunami waves formula is

Answer 11

C = sqrt(gD)

Question 12

Wave energy of Tsunami waves formula is

Answer 12

E = 0.125pgH^2L

Question 13

Drawback (Tsunami)

Answer 13

When a approaching tsunami trough lowers at sea level

Question 14

Tsunami Elevation

Answer 14

The greatest vertical distance from a crest and sea level

Question 15

Inundation distance

Answer 15

The horizontal distance between the normal shore line and the inundation limit

Question 16

Run-up elevation

Answer 16

The vertical distance from the normal shoreline to the inundation limit

Question 17

Coast factors that increase wave height include,

Answer 17

• Sand bars due to shallow depth
• Bays and estuaries due to narrowing of wave energy focus

Question 18

How many waves are in a train, and how long for the entire event

Answer 18

6 - 25 waves, 3-6 hours

Question 19

Storm waves

Answer 19

• Limited drawback and inundation distance
• Wave period: 5 - 20 seconds
• Shallow wave base moves a small amount of water

Question 20

Tsunamis

Answer 20

• Extensive drawback and inundation distance
• Wave period: 10 min - 2 hours
• Deep wave base moves a large volume of water
  Tsunamis have more dynamic pressure due to faster velocity

Question 21

Wind driven waves go how far? And their characteristics

Answer 21

Only make it to the beach, they are more narrow and carry a small volume of water in a single wave.

Question 22

Characteristics of a Tsunami, and how far do waves go?

Answer 22

They go over the beach since they are much wider and carry a large volume of water.

Question 23

Class Question #2
How are storm waves different from tsunamis?

a) Storm waves have deeper wave bases than tsunamis.

b) Storm waves have more dynamic pressure than tsunamis.

c) Storm waves have shorter drawbacks and wave periods than
tsunamis.

d) Storm waves contain greater volumes of water than tsunamis.

Answer 23

c) Storm waves have shorter drawbacks and wave periods than
tsunamis. (correct answer)

Question 24

Destruction from Tsunamis, list the 3

Answer 24

Drawback: Debris and sediments are tumbled and crushed, sand is stripped from beach
Rising Water: Carries boats inland breaking chains, harbors fill up with water
Water moving on shore: Vehicles, trees, and debris are tumbled and crushed, buildings are crushed or carried off foundations

Question 25

Convergent Boundaries

Answer 25

Normal faults develop in sinking lithospheric plates. Thrust faults develop in accretionary prisims

Question 26

Sudden vertical movement displaces water, what do normal, thrust, and strike slip faults do?

Answer 26

Normal: Pull water below equilibrium level Thrust: Lift water above equilibrium level Strike Slip: Do not often produce vertical motion

Question 27

Accretionary Prism (AP) at convergent margin does,

Answer 27

- Shortens horizontally - Thickens vertically - Land elevation slowly rises

Question 28

What two motions occur to AP when slip occurs?

Answer 28

1. Face quickly moves seaward 2. Land elevation quickly sinks

Question 29

What are the Ghost Forests of Cascadia?

Answer 29

Land that has been subsided and has risen again, is filled with dead cedar trunks

Question 30

Continential Margin Sticks

Answer 30

Margin shortens horizontally and rises vertically. Forests grew on dry land.

Question 31

Continental Margin Slips

Answer 31

Margin moves westward from megathrust earthquake Land surface subsides and becomes a salt marsh Forests die in salt water Peat forms in salt marshes

Question 32

How where the Ghost Forests formed?

Answer 32

By Margin stick, then Margin slip, then margin stick

Question 33

Class Question #3 What are emergency officials doing to protect the populations of coastal Washington and Oregon from a future megathrust earthquake? a) creating maps illustrating near-field tsunami inundation levels b) measuring slip along the San Andreas fault and creating models predicting future movement c) draining coastal areas that may be subject to sudden flooding as a result of subsidence d) excavating slopes and creating levees to direct and control sudden flows of seawater

Answer 33

a) creating maps illustrating near-field tsunami inundation levels (correct answer)

Question 34

Subaerial Land slides

Answer 34

Push waters surface down

Question 35

Submarine landslides

Answer 35

Pulls waters surface down, landslide toe pushes waters surface up

Question 36

Class Question #4 Select the tertiary disaster that resulted from the 1998 Papua New Guinea tsunami. a) Two thousand people were killed by the tsunami that carried sand, coral, and debris. b) The force of the wave flattened palm trees on barrier islands between the sea and lagoons. c) Numerous villages along the northern coast were destroyed by the tsunami. d) Witnesses suffered post-traumatic stress and became distraught when discussing the event, even years later.

Answer 36

d) Witnesses suffered post-traumatic stress and became distraught when discussing the event, even years later. (correct answer)

Question 37

Secondary disasters from Tsunamis include,

Answer 37

Tsunamis destroy roads and bridges.  Tsunamis cut power, water, gas, and sewage lines.  Transportation and essential emergency services are blocked.  Mold and rot are common.  Lack of sanitation creates cholera and dysentery infections.  Malaria cases rise from increased mosquito breeding.  Poor, marginalized communities are left traumatized and jobless.

Question 38

Tsunami relive and recovery is challenging because,

Answer 38

Roads are buried or damaged. Communication systems are destroyed Hover crafts may be the only way to access communities Ships often become hospitals

Question 39

Tsunami relief priorities

Answer 39

* Food * Water * Shelter * Health care

Question 40

DART Buoys are? and are used for?

Answer 40

They are buoys that send signals to satellites, from tsunami pressure pulses under the water which are read by a pressure recorder.

Question 41

Class Question #5 How do DART buoys work? a) Buoys emit loud sirens to warn coastal communities of an incoming tsunami wave train. b) Buoys send “take cover” emergency messages to social media apps. c) Buoys send warnings that travel at the speed of light to a receiver on land. d) Buoys create an interlocking superstructure that slows tsunami wave trains while they are in the open ocean.

Answer 41

c) Buoys send warnings that travel at the speed of light to a receiver on land. (correct answer)

Question 42

NOAA organizations include,

Answer 42

* Pacific Tsunami Warning Center * National Tsunami Warning Center * Calculate potential tsunami arrival times

Question 43

Tsunami watch

Answer 43

conditions exist that may generate a tsunami

Question 44

Tsunami warning

Answer 44

A tsunami is approaching

Question 45

Public awareness

Answer 45

Communication and response plans are essential.