Natural Disasters week 4

Why does the wave height of a tsunami increase as the tsunami enters shallow water?

In shallow water, the energy of the tsunami must be contained within a smaller water column

What tools does the Pacific Tsunami Warning Center (PTWC) use in creating tsunami warnings?

PTWC uses ocean buoys, deep-ocean pressure sensors, and satellites to detect tsunamis.

A vast majority of all large tsunami are generated in the ________ Ocean.

Pacific

Which ocean is associated with most tsunamis?

Pacific Ocean

Why was the 2004 Indian Ocean tsunami so deadly?

People did not recognize the signs of an approaching tsunami. People did not immediately evacuate following the offshore earthquake. . Indian Ocean tsunami are relatively rare.

Which of the following best describes how scientists help the public prepare for an earthquake event?

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.

What disturbing force is responsible for producing the majority of tsunami?

The uplift or downdrop of a tectonic plate

Which of the following are unlikely to generate a tsunami?

Transform fault

Why do ships at sea tend not to notice tsunamis?

Tsunamis in deep water have small wave height and long wavelength

What happens to tsunami waves as they move closer to shore?

Velocity decreases and height increases

What caused the Indian Ocean tsunami of 2004?

a 9.2-magnitude earthquake off the coast of Indonesia in the Java Trench

What is a tsunami?

a series of water waves that travel away from a fault in all directions at high speed

What is a tsunami?

a shallow-water wave caused by displacement of the water column a seismic sea wave

What can cause a tsunami

an undersea earthquake a meteor impact on the ocean an undersea landslide an undersea volcanic eruption

What type of plate boundary are most tsunamis associated with?

convergent plate boundaries

A single tsunami produces one wave, either a local tsunami or a distant tsunami.

false

A tsunami can NEVER strike locations on the East Coast of the United States because there are no subduction zones in the Atlantic Ocean.

false

All tsunamis in recorded history have occurred in the Pacific Ocean.

false

Any earthquake in the oceanic crust has the potential to cause a tsunami to form, it mainly depends on the direction that the rocks move during faulting.

false

Human activities are making tsunamis more common and larger.

false

If Japan had a tsunami warning system, then many of the deaths in the 2011 tsunami would have been prevented.

false

If you can see the tsunami coming, you could probably just wait for it and swim to safety.

false

People on the African Coast had only minutes to prepare for the Indonesian tsunami of 2004.

false

Probability analysis can now tell us precisely when and where a tsunami is likely to occur.

false

The entire eastern U.S. coast has one the highest threats from tsunamis in the world.

false

There are no natural service functions of tsunamis; they only cause negative impacts such as death and destruction.

false

There is little chance of another devastating tsunami in Indonesia over the next 100 years because of the tsunami in Indonesia within the past 15 years.

false

There is no way to know where a tsunami is likely to occur.

false

Tsunamis in the open ocean are big enough to capsize freighters and other large boats.

false

Usually, there is only one wave from the tsunami and once it recedes people may return to their homes.

false

Which of the following caused the tsunami that killed 159 people in 1946?

fault movement

The Valdez, Alaska, earthquake created a tsunami that caused extensive damage to the Hawaiian Islands. How long did it take the tsunami to reach Hawaii?

just over 6 hours

A __________ is located at a plate boundary between a subducting slab of oceanic crust and an overlying plate.

megathrust fault

What is a typical tsunami wavelength?

more than 200 kilometers (124.3 miles

A tsunami may result from:

tectonic activity on the seafloor.

An important reason for the extraordinarily high death toll in the Indonesian tsunami of 2004 around the Indian Ocean was that

there was no warning system to alert

How are tsunamis generated?

through displacement of the seafloor under water

A locked fault in a subduction zone represents a major threat for producing a large tsunami

true

A tsunami is a large ocean wave that is most commonly produced when a large earthquake rupture in oceanic crustal rock pushes seawater upwards or downwards

true

Before a tsunami arrives, sea level often drops exposing the seafloor.

true

Buoys in the open ocean can detect the passage of a tsunami.

true

Coastlines that are far from subduction zones have a lower risk for tsunamis compared to coastlines that are near to subduction zones.

true

It is possible to examine the geologic record for ancient tsunamis that were not recorded by humans.

true

Tsunamis can be caused by triggers other than earthquakes.

true

Tsunamis can result in fires and polluted water supplies after they strike an area.

true

Tsunamis have enough erosional power to alter the landscape of coastlines that they hit.

true

Ocean Village wants to put in evacuation route signs. Which directions should the signs direct the villagers to go during a tsunami in order to get people to safety the fastest?

west

of the following locations on the Circum-Pacific Belt are likely to generate a tsunami?

west coast of South America

you had been in a boat in the open ocean as the 1960 Concepción, Chile, earthquake passed, what would have happened to your boat?

you would not feel anything

Look again at the map. Bear in mind that all the earthquake locations that are not inland are on a convergent plate boundary (subduction zone). Which of these statements is true?

All of the locations except 9 could produce tsunamis, as all are subduction zones involving at least one oceanic plate

__________ is a seismic zone that has not produced a large earthquake for a considerable length of time.

A seismic gap

A tsunami is considered to be a:

A shallow water wave

Of the following statements about tsunami, which is/are true? Choose all that apply.

-The tsunami warning system uses seismic waves and deep-ocean pressure sensors to detect tsunami -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." -Tsunami have a very long wavelength, so they travel at very high speeds (equivalent to the speed of a jet airplane.)