Vocabulary
Define magnitude
a measurement of the strength of an earthquake
What can cause an Earthquake?
a shifting fault, the detonation of a nuclear device, a volcano, Other
the point inside the earth where an earthquake begins
What is Focus
What do seismographs record?
Seismic Waves
What causes liquefaction?
As seismic waves pass through the soil, their energy increases the water pressure. The increased water pressure breaks the bonds between soil grains and suspends them in the water. Once enough soil grains are suspended, the soil behaves like a liquid.
a fault in which two fault blocks move past each other horizontally
What is strike-slip fault
Where are earthquakes most likely to occur?
Along Plate Boundaries
Why do aftershocks occur?
Aftershocks occur as a result of a fault continuing to release stress or trying to readjust its position.
What kind of waves cause the most damage during an earthquake
Surface waves cause the most damage during an earthquake.
How long might the epicenter of an earthquake experience aftershocks?
Could occur, for a few hours, days, or weeks afterward
Define fault creep
the slow, almost continuous movement of rock along a fault
Where do earthquakes with the greatest magnitude usually happen?
more than 300 km below the surface
True or False: Earthquakes with a deep focus cause the most severe damage. If False explain why?
False. Earthquakes with a shallow focus usually cause the most severe damage because the seismic waves still have most of their strength when they reach the surface.
True or False: Earth’s crust moves only during noticeable earthquakes. Explain why if False
False. Earth’s crust is in nearly constant motion; noticeable earthquakes are caused when the crust suddenly resumes movement after a time of being stuck.
Where do the most dangerous effects of an earthquake occur?
at the epicenter
an instrument that measures and records earthquake waves
What is seismograph
Explain the difference between intensity and magnitude.
Intensity is a subjective description of an earthquake’s effects on Earth’s surface, but magnitude is a measurement of the energy released by an earthquake.
Explain what a normal fault is?
a fault in which the hanging wall slides down the footwall
a fast surface wave that moves in a side-side pattern as it travels forward
Love Waves
The magnitudes of two earthquakes are measured using the Richter scale. The magnitude of one is 7, and the magnitude of the second is 4. How many times greater was the force of the magnitude 7 than the magnitude 4 earthquake?
1,000 times greater
seismic surface waves that are detected last and move earth particles in an elliptical pattern
What is Rayleigh waves
Where do earthquakes with low magnitudes typically occur?
at divergent plate boundaries
Explain the difference between the movement of a fault during an earthquake and fault creep.
During an earthquake, friction that prevented opposite sides of a fault from moving is suddenly released, and one side moves rapidly over a short distance.
During fault creep, the sides of a fault move slowly and steadily because the friction between them is not great enough to stop them.
Which seismic waves that travel through the earth are detected second by seismograph machines and move the earth perpendicular to the direction they are traveling?
S-Waves
Which of the following represents a good strategy for constructing buildings in an area prone to earthquakes?
They should move with the earth.