Transcript Earthquake Review

Earthquake Test
Review
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Which type of stress stretches rock?
Compression
Shearing
Tension
Diversion
This is a break or a crack in the rock.
Fault
Fissure
Fracture
Mine
This type of fault is caused by
compression.
Normal
Reverse
Strike-slip
Oblique strike-slip
The type of fault shown below:
Normal
Reverse
Strike-slip
Oblique strike-slip
Which type of stress creates the fault
below:
Tension
converging
compression
shearing
The location where an earthquake
begins
epicenter
fault line
focus
seismograph
The point directly above the focus.
Seismogram
Epicenter
Stress
Fracture
All earthquakes happen at plate
boundaries
True
False
The waves that move out in all directions
from the focus on an earthquake.
Seismic waves
Sonic waves
Sound waves
Sonar waves
Type of seismic wave that does the
most damage.
Primary Wave
Secondary Wave
Surface Wave
Sound wave
The first type of wave to arrive at a
seismograph station.
Primary Wave
Surface Wave
Secondary Wave
Sound wave
This type of wave travels only through
solids.
Primary Wave
Surface Wave
Secondary Wave
Sound wave
How many seismograph stations are
needed to determine the epicenter?
One
Two
Three
Four
This measures the amount of energy
released by an earthquake.
Intensity
Strength
Depth
Magnitude
The magnitude scale used today.
Mercalli scale
Richter Scale
Moment Magnitude Scale
Seismograph Scale
Earthquakes can be predicted.
True
False
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5.1 Interactions at Plate Boundaries
Types of Stress

Three main types of stress:
– Tension: rocks are stretched
– Compression: rocks are squeezed
– Shear: rocks slide horizontal in
opposite directions
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5.1 Interactions at Plate Boundaries
Fractures and Faults

A fracture is a break or crack in
rock.
• If rock on side of a fracture has moved
relative to the other side it is called a fault.
• Three main types of faults
• Normal faults
• Reverse faults
• Strike-slip faults
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5.1 Interactions at Plate Boundaries
Reverse Faults


Reverse faults result from
compression stress and slope at an
angle.
Hanging wall up relative to footwall.
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5.1 Interactions at Plate Boundaries
Normal Faults


Normal faults result from tension
stress and slope at an angle.
Hanging wall down relative to
footwall.
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5.1 Interactions at Plate Boundaries
Strike-Slip Faults
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
Strike-slip faults result from shearing
stress and are often vertical.
San Andreas Fault in California.
(p.212)
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6.1 Earthquakes and Plate Boundaries
Focus & Epicenter

The focus is the location on the
fault where an earthquake begins.
• The closer the focus is to
the surface, the stronger
the shaking will be.
• The point on Earth’s
surface directly above
the focus is the
epicenter.
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6.1 Earthquakes and Plate Boundaries
Focus & Epicenter

The focus is the location on the
fault where an earthquake begins.
• The closer the focus is to
the surface, the stronger
the shaking will be.
• The point on Earth’s
surface directly above
the focus is the
epicenter.
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6.1 Earthquakes and Plate Boundaries
Earthquakes Away from
Plate Boundaries


Not all earthquakes happen at plate
boundaries.
New Madris Earthquakes of 1911
• Millions of years ago, a long zone of
intense faulting was formed when the crust
began to pull apart, but did not break
completely.
• Today, the crust is being
compressed, or squeezed
together. (p. 246)
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6.2 Earthquakes and Seismic Waves
Seismic Wave

Waves of energy that are produced
at the focus of an earthquake.
• Waves move outward
from the focus in all
directions.
• 3 main types of
seismic waves.
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6.2 Earthquakes and Seismic Waves
3. Surface Waves
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6.2 Earthquakes and Seismic Waves
1. Primary Waves (P-waves)
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6.2 Earthquakes and Seismic Waves
2. Secondary Waves (S-waves)
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6.3 Measuring Earthquakes
Locating an Epicenter

Triangulation is used to locate the
epicenter.
• This method is based on the speeds of the
seismic waves.
• At least three seismographs must record
the distances.
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6.3 Measuring Earthquakes
Measuring Earthquake Size
Magnitude measures the amount of
energy released by an earthquake.
• Determined by the buildup of elastic strain
energy in the crust, at place where rupture
occurs

• Magnitude scale is based on record of
height of ground motion and ranges
from 0–9.
• Richter Magnitude Scale
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6.3 Measuring Earthquakes
Moment Magnitude Scale

Used today because it is a more
accurate scale for measuring
earthquake size.
• Based on the amount of energy released
during an earthquake.
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6.3 Measuring Earthquakes
Predicting Earthquakes
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
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At this time, geologists cannot
predict earthquakes.
Geologists can, however, determine
the seismic risk by locating active
faults and where past earthquakes
have occurred.
Geologists create seismic risk maps.
(p.274)
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