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Earthquakes Vocabulary Terms

Terms in this set (33)

waves
are a mode of transfer of energy without transfer of mass.
seismic waves
are produced by a rapid release of elastic energy due to stress and are characterized by the "shaking of the ground" (earthquake).
P waves (Primary waves)
vibrate back and forth and parallel to their direction of travel. They produce compression and expansion of the rocks.
S waves (Secondary waves)
vibrate perpendicular to their direction of travel. They change the shape of material.
body waves
travel through the Earth's interior.
surface waves
travel on the surface of the Earth in an "up and down", and side to side motion.
earthquake
is the vibration of the Earth produced by the rapid release of energy.
epicenter
the location on the surface directly above the focus.
focus
also known as the hypocenter, it is the place within Earth where earthquake waves originate.
aftershock
adjustments that take place after a major earthquake that generate smaller earthquakes.
Mercalli Scale
measures the intensity of earthquake. It assesses the physical damages caused by earthquakes. It goes from I to XII.
Richter Scale
is a numerical scale based on the size of the largest seismic waves generated by a quake that is used to describe its magnitude.
tsunami
are huge sea waves or tidal waves with speed up to 500-950km /hour resulting from uplift on part of the ocean floor.
compressional stress
occurs along convergent plate boundary (subduction zone) where plates collide. It shortens and thickens Earth‟s crust by folding, flowing, and faulting. It is the major component in crustal deformation and mountain building
tensional stress
occurs along divergent plate boundary (i.e. mid-ocean ridges). It produces a pull apart effect on rocks. It also creates a thinning and elongation of the Earth‟s crust.
shear stress
occurs along transform fault boundary (i.e. San Andreas fault). It creates a slippage, and major offset on rock layers.
elastic deformation
a type of deformation that does not produce permanent changes in a rock.
ductile deformation
a type of deformation that produces permanent changes in a rock.
faults
are fractures in the crust that produce displacement, offset. They are the result of brittle deformation.
normal fault
a type of dip slip fault in which the hanging wall (block on the upper side of the inclined fault) moves downwards. Normal faults are a result of tensional stress.
reverse fault
a type of dip-slip fault in which the hanging wall moves upwards. It is created by compressional stress.
strike-slip fault
are faults that produce a horizontal displacement of the rock block along the strike of the rock layer. They are associated with shear stress.
intensity
a measure of the degree of earthquake shaking at a given locale based on the amount of damage.
magnitude
is the measurement of the amount of energy released during an earthquake.
seismograph
a device used to measure seismic waves in the Earth's interior.
seismogram
written record of a seismograph.
shadow zone
areas where no P waves or S waves will be found.
amplitude
the maximum disturbance or distance from the resting position.
triangulation
the process of locating the epicenter of an earthquake by using the distances measured from THREE seismic stations.
liquefaction
occurs when unconsolidated materials (such as moist soil) are saturated with water. The vibration caused by earthquakes causes the water to rise up so the surface layer loses cohesiveness. Can cause underground objects such as storage tanks to float to the surface.
lag time
The time difference between when a p-wave and the s-wave reaches a seismograph station.
anticline
A fold in rock that bends upward into an arch
syncline
A fold in rock that bends downward in the middle to form a bowl
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