Earth's Crust in Motion
Measuring Earthquakes
Earthquake Hazards and Safety
Monitoring Faults
Potpourri
100
Describe the movement of a strike-slip fault.
Sides of fault move horizontally past one another with little up or down motion
100
Which waves arrive first as a result of an earthquake?
Primary waves
100
How do soil conditions affect earthquake damage?
Loose soil will create more damage than solid rock
100
Where in the United States is earthquake risk the highest?
West Coast: San Andreas fault
100
What is the force that opposes the motion of one surface as it moves across another?
Friction
200
Why do faults form? Where do they occur?
Due to stress in Earth's crust; at plate boundaries
200
Which waves cause the most damage? Why?
Surface waves; because they are now above Earth's crust
200
What is liquefaction? What can it cause?
When soil turns into liquid mud; can cause landslides or buildings to sink/break apart
200
How does a creepmeter work?
If rock at a fault moves, a wire is pulled that lifts a weight
200
What is the difference between an anticline and syncline?
Anticline: arched up Syncline: scooped downwards
300
Name the 3 types of stress.
Shearing, tension, compression
300
What is the main difference between the focus and epicenter of an earthquake?
Focus: below surface Epicenter: point on the Earth's surface
300
How is a tsunami formed?
An earthquake beneath the ocean pushes water up
300
How does a tiltmeter work?
If the ground moves up or down, water flows from one side of the meter to the other
300
What type of stress causes folding?
Compression
400
What is the difference between a normal and reverse fault in terms of the hanging wall?
Normal: hanging wall slides down Reverse: hanging wall slides up
400
Name 3 scales that are used to measure earthquakes.
Mercalli, Richter, Moment Magnitude
400
What is an aftershock? Why do they cause so much damage even though they are smaller than the first earthquake?
A smaller earthquake that follows a first; because buildings are already weakened
400
How does a laser-ranging device work?
Measures the amount of time it takes for the laser to reflect and bounce back to the observatory house
400
What type of parallel faults create a fault-block mountain?
Normal faults that push rock upwards
500
Match each type of stress with the fault they cause.
Shearing: strike-slip, Tension: normal, Compression: reverse
500
Which is the most efficient of the 3 scales used to measure earthquakes? Why?
Moment Magnitude - can measure earthquakes of all sizes, near and far
500
Describe a base-isolated building. How does it prevent damage?
Has rubber or spring bearings that allow the building to gently sway as opposed to violently shaking
500
How do geologists determine the risk of earthquakes?
Seeing where faults are active; where past earthquakes have occurred
500
What is a plateau? What type of faults create them?
Flat-topped elevated block of rock; parallel normal faults push rock upwards
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