19.1 & 19.2
f
(t/f) On seismograms, seismic waves recorded from more distance facilities are closer together than those recorded from facilities close to the epicenter.
t
(t/f) P-waves are bent when they strike the core.
t
(t/f) P-waves travel through Earth's mantle.
t
(t/f) S-waves do not travel through Earth's mantle.
t
(t/f) Seismic waves change speed and direction when they encounter different materials.
t
(t/f) Seismologists have reasoned that Earth's outer core must be liquid based on the disappearance of S-waves.
f
(t/f) Studies of how waves reflect deep inside Earth show that Earth's inner core is solid.
f
(t/f) Surface waves are the first to arrive at a seismic facility.
t
(t/f) The P-wave shadow zone does not receive direct P-waves.
seismogram
A paper or computer record of earthquake vibrations.
frame
All seismometers include a _____ suspended from a wire or spring.
mass
All seismometers include a _____ that is anchored to the ground and vibrates during an earthquake.
seismometer
An instrument that records earthquake vibrations.
Elastic
At a lower stress value, _____ deformation occurs.
s & p waves
Can pass through Earth's interior.
s waves
Causes rock to move at right angles to the direction in which the wave travels.
surface waves
Causes rock to move both up and down and from side to side.
strain
Deformation of materials in response to stress.
San Andreas
Famous California strike-slip fault.
fault plane
Fault surface along which movement takes place.
compression
Force that tends to shorten or squeeze something, decreasing its volume.
tension
Force that tends to stretch or elongate something.
fault
Fracture along which movement occurs.
Strike-slip fault
Fracture caused by horizontal shear.
normal fault
Fracture caused by horizontal tension.
reverse fault
Fracture that forms as a result of horizontal compression.
plastic
Rocks at great depths are _________.
brittle
Rocks nears Earth's surface are generally ________.
p waves
Squeezes and pulls rock in the same direction as the wave travels.
plastic deformation
The high stress deformation of a material (failure & _____ limit).
elastic deformation
The low stress deformation of a material (zero & _____ limit).
stress
Total force acting on crustal rocks per unit area.
surface waves
Travels only along Earth's surface.
fails and breaks
When stress exceeds the strength of a material, it...