Download Earthquakes Test Study Guide

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CHAPTER 2 - EARTHQUAKES – STUDY GUIDE
Section 2.1 - FORCES IN EARTH’S CRUST
3 Types of Faults
Type of Fault
Normal
Reverse
Strike-slip
Stress
tension
compression
shearing
Stress Motion
Direction of land movement
downward
upward
little upward or downward
movement
3 Types of Stress
 stress- a force that acts on rock to change its shape or volume
 tension- stress force that stretches rocks apart so that it becomes thinner in the middle (ex. like pulling apart a
piece of warm bubble gum)
 compression- stress force that squeezes rock until it folds or breaks (ex. like a giant trash compactor)
 shearing- stress force that pushes a mass of rock in two opposite directions (ex. rock can break/slip apart or
change shape)
Features Formed
 hanging wall- block of rock that slips downward in a normal fault/ moves upward in a reverse fault
 footwall- block of rock that doesn’t move
 anticline-a fold in rock that bends upward into an arch (anticline = arch)
 syncline- a fold in rock that bends downward into a valley (syncline = sinks)
 plateau- a large area of flat land elevated high above sea level
Section 2.2 EARTHQUAKES AND SEISMIC WAVES
Important Terms
 earthquake- the shaking and trembling that results from the movement of rock beneath Earth’s surface
 focus- the point beneath the Earth’s surface where rock that is under stress breaks and triggers an earthquake
 epicenter- the point on the Earth’s surface directly above the focus
 magnitude- the number that geologists assign to an earthquake based on the earthquake’s size
3 Types of Seismic Waves
Type of Seismic Wave
Arrival Time
Motion
Amount of Damage
P wave
(Primary waves)
first, fastest
compress and expand like an
accordion
minimal (not a lot)
S wave
(Secondary waves)
surface wave
second, medium speed
side to side & up and down
moderate
last, slowest
causes ground to move like
an ocean wave
severe
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3 Types of Scales
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Mercalli Scale- rates earthquakes according to the level of damage at a given place- 1 to 12
Richter Scale- rating of an earthquake’s magnitude based on the size of the earthquake’s seismic waves- 1 to 10
Moment Magnitude Scale- rating system that estimates the total energy released by an earthquake
SECTION 2.3 – MONITORING EARTHQUAKES
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seismograph- instrument that records and measures seismic waves
seismogram- pattern of lines on a seismograph
friction- force that opposes the motion of one surface as it moves across another surface
SECTION 2.4 - EARTHQUAKE SAFETY
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liquefaction- occurs when an earthquake’s violent shaking suddenly turns loose, soft soil into liquid mud causing
the buildings to sink and pull apart
aftershock- an earthquake that occurs after a larger earthquake in the same area; may strike hours, days, or
even months later
tsunami- a large ocean wave formed when water is displaced by an earthquake
base-isolated building – a building designed to reduce the amount of energy that reaches the building during an
earthquake; it rests on shock-absorbing rubber pads or springs