22.5 Earthquakes
Where are most earthquakes concentrated?
Along plate boundaries.
T or F? Rocks tend to fold instead of break under low temperature or pressure.
False
Name three ways that stress can affect rocks.
It can squeeze them together. It can stretch or pull them apart. It can push them in different directions.
What are some characteristics of a fold?
It is a bend in layers of rock. It forms where rocks are squeezed but do not break.
What is a seismograph?
It is a device geologists uses to record seismic waves.
What is stress?
It is a force within Earth that either squeezes rocks together, pulls them apart, or pushes them in different directions.
What is an earthquake?
It is a movement of Earth's lithosphere that occurs when rocks in the lithosphere suddenly shift, releasing energy.
What is the epicenter?
It is the location on the Earth's surface directly above the focus of an earthquake.
What is the focus?
It is the location underground where an earthquake begins.
What are some characteristics of a fault?
Many occur along plate boundaries. It is a break in a mass of rock where movement happens.
Which kind of seismic waves are typically the first to be detected at a distance?
P waves.
Describe P waves.
Seismic, longitudinal waves similar to sound waves that cause particles in the material to vibrate in the direction of the waves' motion.
Describe surface waves.
Seismic, slowest-moving type of wave that develops when seismic waves reach Earth's surface.
Describe S waves.
Seismic, transverse waves that cannot travel through liquids.
Describe characteristics of the physics of earthquakes.
Stress builds in areas where rocks along fault lines snag and remain locked. Potential energy is transformed into kinetic energy in the form of seismic waves. In an earthquake, rocks break and grind past each other, releasing energy.
What are seismic waves?
They are vibrations caused by an earthquake that carry the earthquake's energy away.
Why do earthquakes occur?
They happen because underground stress forces have exceeded the strength of rock.
T or F? Some earthquakes will occur in the interior of plates.
True
Stress from moving tectonic plates produces ___________________ and ________________ in Earth's crust.
faults and folds
An earthquake releases _______________________ energy that is carried by vibrations called _____________________________.
potential or stored energy seismic waves
When seismic waves interact with boundaries between different kinds of rock within Earth, they can be _________________, __________________, or __________________.
reflected, refracted, or diffracted
