Geology exam 2
To determine the epicenter of an earthquake, scientists
find the intersection of P and S arrival time data from three seismographs at different locations
The greatest earthquakes with magnitudes over 9 are usually associated with
subduction zones.
Which kind of material would be prone to liquefaction during an earthquake?
water- saturated sand
Volatiles will increase the melting temperature of the rock.
False
Which of the following describes the tsunami in Lituya Bay, Alaska in 1958?
M 7.7 earthquake triggered a massive landslide, which fell into the water and caused water to surge over 500 m above the normal water level.
Which of the following places in the U. S. has the lowest seismic hazard?
Minneapolis, MN
Which scale is most useful to describe the absolute size of an earthquake and the energy released during an earthquake?
Moment Magnitude Scale
Which of the following sequences correctly lists the different arrivals from first to last?
P waves ... S waves .... Surface waves
Which seismic waves produce the smallest amplitude?
P-waves
Coastlines that are far from subduction zones have a lower risk for tsunamis compared to coastlines that are near to subduction zones.
True
Earthquakes along the east coast of the U.S. are generally felt at greater distances from the epicenter tan similar sized earthquakes in California.
True
Magma with a higher silica content will also have a higher viscosity.
True
Why do sailors rarely notice a tsunami passing in the open ocean?
Tsunamis are too small in amplitude in the open ocean, and the distance between crests is too large to notice its passing
Why don't boats in the open ocean notice a tsunami approaching?
Tsunamis are too small in amplitude in the open ocean, and the distance between crests is too large to notice its passing.
How do rock particles move during the passage of a P wave through the rock?
back and forth parallel to the direction of wave travel
Human activity can cause earthquakes through all these ways except
building over fault lines.
Each interval of VEI from level 2 represents a ______ increase in volume of ejected material
10 times
Where is the majority of lava extruded?
At divergent plate boundaries
Which of the following magma types will usually flow the fastest?
Basaltic
In order of increasing silica content, the three major types of magma are
Basaltic, andesitic, rhyolitic
Which of the following is FALSE about the shaking from earthquakes?
Consolidated bedrock causes more ground shaking than mud because the seismic waves are transmitted more efficiently in bedrock.
What is not a natural service function of earthquakes?
Destroy natural underground dams that slow or redirect flows
Which of following plate boundaries are associated with magma from decompression melting?
Divergent boundaries
Mexico City was built on mud deposits. How will this affect the earthquake hazard there?
Earthquakes shaking will be increased
Which of the following regions has the LEAST risk from tsunamis?
East coast of the U.S.
A single tsunami produces one wave, either a local tsunami or a distant tsunami.
False
All earthquakes in the U.S. are situated on the West Coast near the San Andreas Fault.
False
What are volatiles?
Gases trapped in the magma
Which is not a type of seismic wave?
Ground wave
Which of the following describes the tsunami in Indonesia in 2004?
M 9 earthquake triggered a 10 m tsunami, which was the deadliest tsunami ever, killing more than 200,000 people in several countries
What is the difference between magma and lava?
Magma is found below the Earth's surface, lava is found on the Earth's surface.
Why are so many volcanoes found on the Ring of Fire around the margin of the Pacific Ocean?
Many subduction zones occur there
How do humans increase the risk of tsunami hazards?
Moving to the coasts where the effects of tsunamis are greatest.
In which of the following faults does the hanging-wall move down relative to the footwall?
Normal dip-slip fault
Which of the following is FALSE about magma?
Tectonic plates move around on an underground ocean of magma
Which of the following is TRUE about seismographs taken far from the epicenter of the earthquake as compared to those that are closer?
The P and S waves will be farther apart.
Based on Seismic Gap Hypothesis, where along a fault are you most likely to see a large earthquake?
The area on the fault that has not moved in a long time
Why don't earthquakes on transform faults trigger tsunamis?
The earthquakes don't vertically displace the water in the ocean.
What is "runup"?
The farthest horizontal and vertical distance that tsunami waves move inland
What happens as a tsunami nears land?
The height of the waves increases due to a decrease in both water depth and tsunami velocity
What happens as a tsunami nears land?
The height of the waves increases due to a decrease in both water depth and tsunami velocity.
In which of the following tectonic plate settings are volcanoes typically NOT found?
Transform fault
Earthquake A has a M7 as compared with earthquake B's M6. The amount of energy released by A is ______ than B
about 32 times greater
In general, there is more ground shaking from an earthquake with
decreasing depth from the surface and decreasing distance to the epicenter.
The most appropriate scale to use to compare earthquakes around the world is the
moment magnitude scale