Earth Science Study Guide, Earthquakes

anticline
Fold in rocks that arches upward so older rocks are at the center.
basin
circular syncline that forms a depression in the ground
compression
stress that squeezes rocks together
confining stress
stress from the weight of material above buried rocks that does not allow the rocks to change shape
deformation
change in the shape of rocks due to stress
dip-slip fault
fault in which the dip of the fault plane is inclined relative to the horizontal surface of the earth
dome
circular anticline that forms a mound on the ground
fault zone
fracture along which one side has moved relative to the other
fold
bend in rocks caused by compression
footwall
block of rocks that is beneath a dip-slip fault plane
fracture
crack in rocks caused by stress
hanging wall
block of rocks that is above a dip-slip fault plane
joint
break in rocks along which there is no movement
monocline
bend in rocks that causes them to be inclined relative to the horizontal
normal fault
dip-slip fault in which the hanging wall drops down relative to the footwall
reverse fault
dip-slip fault in which the hanging wall pushes up relative to the footwall
shear
parallel stresses on rocks that push them past each other in opposite directions
slip
distance rocks move along fault
stress
force per unit area on rocks
strike-slip fault
fault in which the dip of the fault plane vertical
syncline
fold in rocks that bends downward so younger rocks are at the center
tension
stress that pulls rocks in opposite directions
thrust fault
reverse fault which the dip of the fault plane is nearly horizontal
wavelength
horizontal distance between two corresponding points on adjacent waves, such as the distance
between two crests or two troughs
amplitude
height of a wave from the center to the top of a crest (or bottom of a trough)
body wave
type of seismic wave that travels through Earth’s interior; either a primary wave or a secondary
wave
crest
highest point of a wave
earthquake
ground movement caused by the sudden release of energy stored in rocks
elastic rebound theory
theory that earthquakes occur when rocks break and snap back to their original
position after being deformed elastically until they cannot deform any more
epicenter
point on the surface directly above the focus of an earthquake
focus
point beneath the surface where rocks break and start an earthquake
love wave
type of seismic wave that travels over the surface and has a side-to-side motion
primary wave (p-wave)
type of seismic wave that travels through Earth and arrives first at a seismometer
rayleigh wave
type of seismic wave that travels over the surface and has an up-and-down motion
secondary wave (s-wave)
type of seismic wave that travels through Earth and arrives second at a seismometer
surface wave
type of seismic wave that travels along the surface of the ground; either a Love wave or a
Rayleigh wave
trough
lowest point of a wave
tsunami
large water wave cause by any shock to ocean water, such as an earthquake, meteorite impact,
landslide, or nuclear explosion
Mercalli intensity scale
scale of earthquake intensity based on what people feel and the extent of damage caused by the earthquake
moment magnitude scale
scale of earthquake magnitude based on the total amount of energy released by an earthquake
Richter magnitude scale
scale of earthquake magnitude based on the amplitude of the largest seismic wave produced by an earthquake
seismogram
paper record of seismic activity produced by a seismograph
seismograph
older type of device that measures and records seismic waves using a suspended, weighted pen that writes on a drum of paper that moves with the ground
seismometer
modern device that uses electronic motion detectors to measure and record seismic waves and other ground motions