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Forces
Safety
Stress
Faults
Magnitude
100
What is the area beneath earth's surface where rock that is under stress breaks and triggers an earthquake?
The focus.
100
What is the type of stress that squeezes rock together until it folds or breaks producing a reverse fault?
Compression
100
This seismic wave moves more slowly than the other waves, but they can produce severe ground movements.
Surface waves
100
Most earthquakes begin where?
In the lithosphere.
100
What is the seismic wave that shakes the ground back and forth?
S Waves or secondary waves
200
What is the stress force that pulls on the crust where two plates are pulling apart?
Tension
200
What is the scale most often used by geologists today that measures the total energy released by an earthquake?
The moment magnitude scale.
200
What happens during Liquefaction?
The earthquake's shaking suddenly turns loose soil in liquid mud.
200
What are the four instruments used by geologists to monitor faults?
Tiltmeters, Creep Meters, Laser-ranging Devices, and GPS Satellites
200
How is a reverse fault formed?
By compression where the rock of the crust is pushed together.
300
What is the Mercalli Scale used for?
It is used to measure the amount of damage that occurs to the ground, homes, and other buildings at a given place.
300
What is the first seismic wave to arrive at the surface?
Primary Waves (P waves)
300
This can occur hours, days, or months after an earthquake and still cause damage.
An aftershock
300
How does a fault-block mountain form?
It forms when two normal faults cut through a block of rock.
300
What does the magnitude of an earthquake tell geologists?
The amount of energy that was released by the earthquake.
400
Why can geologists not predict earthquakes?
Because they cannot be sure when and where stress will be released along a fault.
400
Where are earthquakes more likely to occur?
Where plate movement stores energy in the rock along faults.
400
Which seismic wave vibrates from side to side as well as up and down?
S waves
400
In what part of the U.S. are the risk of earthquakes the highest? Why?
Along the pacific coast: California, Washington, Alaska because that is where the plates meet causing many active faults.
400
Where is the epicenter of an earthquake located?
On the surface right above the earthquake's focus.
500
What is an anticline?
A fold in rock that bends upward into an arch.
500
What are the differences between a normal fault and a reverse fault. Use a diagram with written response.
In a normal fault, the fault is at an angle so that one block lies above the other, but with a strike-slip fault the rocks slip past each other. A strike-slip fault has little up and down movement.
500
What is a plateau?
A large area of flat land elevated high above sea level.
500
What is a tsunami?
A large wave that is formed by the water that is displaced during an earthquake.
500
The ground movements caused by seismic waves can be recorded by what instrument?
A seismograph