EAPS 106 EXAM 2 QUESTIONS WITH VERIFIED
ANSWERS
What is the process that makes subduction zone earthquakes cause tsunamis?
Uplift of the seafloor from elastic rebound during a large subduction zone
How tsunami and wind-blown waves differ (3)
Tsunami waves can have similar heights to large wind blown waves, but:
1. carry a much larger volume of water
2. have a much longer wavelength (distance from crest to crest)
3. travel much further inland.
How does a tsunami wave in deep water change when it hits shallow water?
In deep water, long wavelengths, low wave height, and great speed (jet)
Approaching shore, they slow which causes the back of the wave to catch up. Reduces
wavelength, but increases wave height.
When do water waves typically break?
When the wave height is equal to water depth
Wave Height = Water Depth
What type of earthquakes will cause a tsunami?
subduction zone, caused by energy of ocean floor shifting
How do we know about past tsunamis in Japan and the West Coast?
Tsunami Stones in Japan
Sand deposits
How many people have been killed by tsunamis in the past 1,000 years?
Several Hundred Thousands
What might it mean if you feel shaking near the shore?
Tsunami 20-40 min away
why does the sea level drop before a tsunami?
the ocean is being dragged out when the trough arrives before the crest.
Why is it dangerous to return to the shore after a tsunami wave?
Consists of 3-10 waves and 2nd or 3rd wave is largest
Why did so many people die around the Indian ocean during 2004 tsunami?
, 1961 Chilean earthquake made tsunamis all over. Did not have early warning systems
How does the DART tsunami early warning system work?
1. Pressure sensor on ocean floor measure water pressure
2. Measurements are sent by acoustic signal to a buoy on the surface
3.Buoy sends signal to satellite
4. Signal sent to early-warning stations on land
-can send 15 min after earthquake, including path and size
Which process has the potential to cause the largest tsunamis?
1. asteroid impacts
2. volcanic eruptions
3. landslides
4. local earthquakes
5. distant earthquakes
Know what caused the largest tsunami runup in the past 100 years
An avalanche (landslide) in Alaska
How do the Hawaiian Islands generate tsunamis?
Underwater landslides
What will most likely cause a tsunami in the Atlantic ocean?
Underwater landslides
What are the tectonic settings where the different types of volcanism are found? (3)
1. Mid-ocean ridges
2. Subduction zones
3. Hot spots
Is the mantle a subsurface ocean of magma?
No
What process will cause already hot, but not yet melted rocks, to melt?
1. Increase temperature
2. Decrease pressure as rock rises
Add water to decrease melting temp
What causes hot rocks to melt at each of the tectonic settings where volcanoes are found?
In Subduction Zones and in Hotspots
ANSWERS
What is the process that makes subduction zone earthquakes cause tsunamis?
Uplift of the seafloor from elastic rebound during a large subduction zone
How tsunami and wind-blown waves differ (3)
Tsunami waves can have similar heights to large wind blown waves, but:
1. carry a much larger volume of water
2. have a much longer wavelength (distance from crest to crest)
3. travel much further inland.
How does a tsunami wave in deep water change when it hits shallow water?
In deep water, long wavelengths, low wave height, and great speed (jet)
Approaching shore, they slow which causes the back of the wave to catch up. Reduces
wavelength, but increases wave height.
When do water waves typically break?
When the wave height is equal to water depth
Wave Height = Water Depth
What type of earthquakes will cause a tsunami?
subduction zone, caused by energy of ocean floor shifting
How do we know about past tsunamis in Japan and the West Coast?
Tsunami Stones in Japan
Sand deposits
How many people have been killed by tsunamis in the past 1,000 years?
Several Hundred Thousands
What might it mean if you feel shaking near the shore?
Tsunami 20-40 min away
why does the sea level drop before a tsunami?
the ocean is being dragged out when the trough arrives before the crest.
Why is it dangerous to return to the shore after a tsunami wave?
Consists of 3-10 waves and 2nd or 3rd wave is largest
Why did so many people die around the Indian ocean during 2004 tsunami?
, 1961 Chilean earthquake made tsunamis all over. Did not have early warning systems
How does the DART tsunami early warning system work?
1. Pressure sensor on ocean floor measure water pressure
2. Measurements are sent by acoustic signal to a buoy on the surface
3.Buoy sends signal to satellite
4. Signal sent to early-warning stations on land
-can send 15 min after earthquake, including path and size
Which process has the potential to cause the largest tsunamis?
1. asteroid impacts
2. volcanic eruptions
3. landslides
4. local earthquakes
5. distant earthquakes
Know what caused the largest tsunami runup in the past 100 years
An avalanche (landslide) in Alaska
How do the Hawaiian Islands generate tsunamis?
Underwater landslides
What will most likely cause a tsunami in the Atlantic ocean?
Underwater landslides
What are the tectonic settings where the different types of volcanism are found? (3)
1. Mid-ocean ridges
2. Subduction zones
3. Hot spots
Is the mantle a subsurface ocean of magma?
No
What process will cause already hot, but not yet melted rocks, to melt?
1. Increase temperature
2. Decrease pressure as rock rises
Add water to decrease melting temp
What causes hot rocks to melt at each of the tectonic settings where volcanoes are found?
In Subduction Zones and in Hotspots
