Quiz Chapter 11 Flashcards Preview

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Flashcards in Quiz Chapter 11 Deck (37):
1

Earthquake

ground shaking caused by the sudden and rapid movement of one block of rock sliding past one another

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Faults

rocks sliding past one another along fractures in the crust

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focus or hypocenter

where the rock slippage of the Earthquake originates in the ground

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Seismic waves

stored up energy released in all directions from the focus

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epicenter

point on the ground surface directly about the focus

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Causes of Earthquakes

Massive landslides, meteorites, and volcanic eruptions, plate movement

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elastic rebound

deformed rocks "snap back" to their original position in this process

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aftershocks

small earthquakes that follow major earthquakes

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foreshocks

minor earthquakes that sometimes precede a major earthquake by days, weeks, or months

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Three major types of faults

Normal, Reverse and thrust, and Strike-slip faults

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Normal Fault

associated with divergent plate boundaries

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Reverse and thrust

associated with convergent plate boundaries
Megathrust fault: in a subduction zone, the boundary between the subducting and overlying plate

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Strike-slip

large faults associated with divergent plate boundaries
Small strike-slip faults associated with divergent plate boundaries

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Types of Faults

Some portions exhibit slow, gradual displacement known as fault creep
Other segments regularly slip, producing small earthquakes, others remain stuck and store elastic energy

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Fault slip

the amount of displacement on the fault surface

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Seismology

study of earthquake waves
Chinese 2000 years ago

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Seismographs

record the movement of Earth in relation to a stationary mass on a rotating drum or magnetic tape
More than one is needed to record horizontal and vertical ground movement

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Seiesmograms

records seismic waves

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types of seismic waves

Surface waves, P waves, S waves (P and S are Body Waves)

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Surface waves

travels in the rock layers just below Earth's surface
-two general directions of motion
-One causes the ground to move up and down
-second causes the ground to move side to side (Greatest destruction)
slowest waves highest amplitude
Cause greater damage than Body waves

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Body waves

travel through Earth's interior

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P waves

Body wave
are compression waves
can travel through all materials
Fastest moving waves
lowest amplitude

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S waves

Body wave
are shear waves
Can only travel through solid material
Travel slower than P waves

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Two measurements of the size of an earthquake

Intensity and Magnitude

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Intensity

measure of degree of earthquakes shaking at give locale based on amount of damage

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Magnitude

An estimate of the amount of Energy released at the source of the earthquake

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Intensity scales

Modified Mercalli Intensity scale
may not be accurate

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Intensity can very due to

soil; type of rocks under the surface of certain locations

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Magnitude scales

Richter scale
Amplitude of the largest seismic wave
Moment Magnitude: total energy released during an earthquake

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Amount of destruction varies on:

Magnitude of the earthquake
Proximity to epicenter

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Liquefaction

process where loosely packed, waterlogged sediments behave as a fluid during the intense shaking of an earthquake

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seiches

rhythmic sloshing of water in lakes, reservoirs, and enclosed basins

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Landslides and Ground Subsidence

Ground shaking causes loose sediments on a slope to slump

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Fire

Can start when gas and electrical lines are destroyed by an earthquake
Broken water lines make fire control probkematic

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Tsunami

series of large ocean waves
generated by displacement from a megathrust fault
Close to shore, the water "piles up" and can exceed 30 meters in height

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95% percent of energy released from earthquakes originates

along circum-Pacific belt
Most earthquakes occur along megathrust faults of convergent plate boundaries

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seismic gaps

tectonically quiet zones along a fault where strain is currently building up