Forces in Earth's Crust
Earthquakes and Seismic Waves
Monitoring Earthquakes
Earthquake Safety
I Should Know This
100
This is a force that acts on rock to change its shape or volume.
What is stress?
100
This seismic wave arrives first at a seismograph.
What are P waves?
100
The Richter scale rates earthquakes based on this.
What is the size of their seismic waves as measured by a seismograph.
100
People can do this to protect themselves if they are indoors when an earthquake strikes.
Acceptable answers: What is Drop, cover, and hold. Crouch beneath a table or desk and hold onto it. If a desk or table are not available, crouch against an inner wall and cover your head and neck. Avoid outer walls, windows, mirrors, wall hangings, and furniture that might topple.
100
This is a break in the crust where slabs slip past each other.
What is a fault?
200
This stress force pulls on the crust and stretches rock.
What is tension?
200
This is the point beneath the earth's surface where the crust breaks and triggers an earthquake.
What is the focus?
200
The Mercalli scale rates earthquakes based on this.
What is the intensity of their effects on buildings and the land at a particular location.
200
Water displaced by an undersea earthquake produces this.
What is a tsunami?
200
True or False The type of stress that pushes masses of rock sideways in opposite directions is tension.
What is true?
300
This type of stress force produces a strike-slip fault.
What is shearing?
300
This is the point on earth's surface directly above and earthquake's focus.
What is the epicenter?
300
True or False By drawing circles to show distances from three seismograph stations, geologists can locate the magnitude of an earthquake.
What is False?
300
This process occurs when an earthquake's shaking turns loose soil into mud.
What is liquefaction?
300
This is a large area of flat land that is elevated high above sea level.
What is a plateau?
400
Anticlines and synclines are two types of this.
What are folds?
400
This is a rating system that estimates the total energy released by an earthquake.
What is moment magnitude scale?
400
In Chicago the time for P waves to arrive was 3 min and 45 sec. The time for S waves to arrive was 7 min. What is the difference between P and S wave arrival?
What is 3 min and 15 sec.
400
True or False A base-isolated building design increases the amount of energy that reaches the building during an earthquake.
What is False?
400
How could you use the distance to an epicenter from three cities to locate the earthquake's epicenter?
What is draw a circle to scale on a map to show each city's distance from the epicenter. The point at which the three circles intersect is the epicenter.
500
This type of fault forms when the hanging wall moves upward past the footwall.
What is reverse fault?
500
This type of seismic waves produces the most severe ground movements.
What are surface waves?
500
Geologists use these four instruments to monitor earthquakes.
What are Tiltmeters, creep meters, laser-ranging devices, and GPS satellites?
500
This is an earthquake that occurs after a large earthquake centered in the same area.
What is an aftershock?
500
It is difficult for geologists to predict earthquakes because of this.
Acceptable answers: What is geologists can monitor movements of the land surface but not movements deep below ground. Geologists hypothesize but do not know for certain that slight movements on the surface signal an impending earthquake. Geologists have no way of knowing how soon the earthquake may strike.
M
e
n
u