Name______________________Period____
Note Outline: Earth Science Chap 19 Earthquakes
1. Define stress vs. strain as they apply to rocks.
a. 3 types of each
b. Type of fault & boundary associated with each type of stress
2. Distinguish among the 3 types of faults.
3. Contrast types of seismic waves-3 types according to their type of movement, speed, location
4. Focus vs. epicenter
5. Seismograph/seismometer vs. seismogram
a. Describe how machine works
b. Explain how seismic waves give clues about Earth’s interior
6. Compare & contrast magnitude & intensity, and the scales to measure each
a. Richter vs. Mercalli scale
7. Describe Earth’s seismic belts
8. Locating an epicenter; Explain why data from at least 3 seismic stations is needed.
9. Explain how and why tsunami waves change as they approach shore.
10. Explain some of the factors considered in earthquake probability studies.
a. Seismic risk-history, seismic gap, strain accumulation
Section 19.1 Forces within Earth
Stress: _____________ per unit area, 3 subtypes
1. Compression: ______________________. Causes __________________
in the length of the surface.
2. Tension: _____________________. Causes _______________ in length
3. Shear: ___________________ pressure
Strain: Deformation (______________) of material in response to stress
1. Elastic strain: _________________deformation (bending, compression or stretching). Goes back to
_____________________ shape when stress is gone
a. Elastic limit: Amount of stress a rock can withstand and still return to original shape
2. Ductile deformation: _________________ deformation. _____________ return to original shape after
stress is gone.
3. Failure: Material (rocks) __________________
Faults:_____________ in Earth’s crust along which __________ occurs when stress causes _________
3 subtypes:
1. Normal Fault: Rock ___________________ the slope normally
a. Force: ______________ (pulling or stretching)
b. Boundary type: ___________________
c. Diagram: Side view: Length along earth’s surface is ______________ due to ___________
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2. Reverse fault: Upper surface forced ______________
a. Force:________________
b. Boundary type: ________________
c. Diagram: Side view: Length along earth’s surface is ___________ due to compression
3. Strike-Slip Fault: Rocks ______________ each other wtihout upward or downward movement
a. Force: ___________
b. Boundary type: _______________
c. Example: San ____________________
d. Diagram: Top view-streams, fence posts offset
Earthquake Waves: Caused when the ___________ limit is reached and rocks fail or break. Due to pressure
build-up when rocks ____________________.
3 subtypes
1. Primary Waves: Rock particles move back & forth in the _________ direction that the wave travels
a. AKA P-wave: ______________ wave
b. Location: ________________(________________-starts at focus)
c. Can travel through ____________________, but slowed & bent in liquid
d. ______________ wave. Arrives at seismograph station _______
e. Diagram:
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2. Secondary Waves: Rock particles move at _________________ to the direction the wave travels
a. AKA S-wave: ____________________ wave, underground
b. Location: ________________(________________-starts at focus)
c. Can ONLY travel through ______________. Therefore some seismograph stations don’t receive S
waves.
d. _____________________ speed wave
e. Diagram:
3. Surface Waves: Rock particles move in _____________________ at once: backward, rolling motion &
side to side swaying motion
a. No nickname
b. Location: ____________________ (Start at _________________, NOT focus)
c. Causes most of the _________________
d. _____________________ wave
e. Diagram:
Focus: Point where earthquake _______________ & seismic waves ________________
Epicenter: Point on earth’s _______________ directly _______________ the focus.
Section 19.2 Seismic Waves & Earth’s Interior
1. Seismology: Study of earthquake waves
2. Seismometer (AKA Seismograph): Instrument that detects & records seismic waves
a. Rotating drum with paper & pendulum with pen attached.
b. When seismic waves arrive, ____________ is shaken but the _________ stays stationary
3. Seismogram: Record on paper or in computer produced by a seismometer
a. The farther apart in time that the ________________________ arrive, the farther the epicenter
is from the seismograph station
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Clues to Earth’s Interior
When waves hit Earth’s core:
1. Shadow Zones: Areas of Earth that do not detect seismic waves because
A. P-waves are refracted (___________) & ____________ by the liquid outer core
B. S-waves do _______ enter the liquid core. They ________________ and are lost.
2. Wave speeds can be used to map Earth’s internal structure and determine:
A. Whether it is ________________________
B. Determine the ________________________-iron vs. granite, etc.
Earth’s interior:
1. Inner core: _________________, dense. Made mainly of ____________.
2. Outer core: _______________, mainly iron.
3. Mantle:
a. _____________ layer of earth.
b. Made of ______________________.
c. Divided into upper & lower mantle based on different seismic wave speeds
4. Crust: Outermost layer. ________________ crust is _____________________ than oceanic crust.
5. Lithosphere plates: _____________ combination of ___________ & ____________ mantle
Section 19.3 Measuring & Locating Earthquakes
1. Seismologist: Scientist who studies earthquakes
2. Magnitude: Amount of ___________________released during an earthquake. Based on:
a. Richter scale: Measures (_________________) magnitude of an earthquake
i. Based on size of the ______________ seismic waves on a seismogram
ii. No upper limit
iii. Most earthquakes are _________ to be _____ by humans (< 3.0)
iv. Only ______ number on the Richter scale for each quake
3. Intensity: Amount of ______________ & ___________ damage
a. Modified Mercalli Scale: Measures intensity in a _______________ location
i. Roman numerals I to XII
ii. I (low) is not felt vs. XII is total destruction
iii. Damage is caused by _____________waves
iv. _______________numbers for each quake, as different locations have different
amounts of damage
v. Dependent on: magnitude, depth of quake, type of rock or surface material, structure
design & distance from epicenter.
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Locating an Earthquake:
1. Epicentral distance = The distance between the seismic station and the __________________
2. Must have a minimum of 3 seismic station readings to determine the epicenter location. Why?
a. If there is only 1 station, the epicenter could be__________ on
circle
b. If there are 2 stations, the epicenter could be in _________
places
c. If there are 3 stations, the epicenter could be in
_________________ - where all three circles meet
the
3. Most earthquakes occur in seismic belts along _____________________
Section 19.4 Earthquakes & Society
Tsunami: Large _________________ wave created by vertical motion of ocean floor during a quake
1.
2.
3.
4.
At sea, the wave is ________________ high
As the wave enters shallow water & height increases to over 30m (100 feet)
Speeds of 500-800km/h
Spreads in all directions across the entire ocean
Seismic Risk based on:
1. Past seismic activity: _______________of earthquakes
a. Earthquake recurrence rate: Fault may rupture at regular intervals
b. Lasers are used to ___________________ in high recurrence areas to predict a potential
quake
c. Seismic gap: An active fault that ______________ had a significant earthquake for a long time
Chapter 19: Earthquakes-Test Topics
Computer Review: http://www.glencoe.com/sec/science/earthscience/index.html
a. Chapter Resources
b. Unit 5
c. Chapter 19
1. Stress vs. strain
a. 3 types of each
b. Type of fault & boundary associated with each type of stress
2. Faults-3 types
3. Seismic waves-3 types
a. Type of movement, speed, location
4. Focus vs. epicenter
5. Seismograph/seismometer vs. seismogram
a. How works
6. Earth’s interior-clues from waves
7. Magnitude vs. intensity
8. Richter vs. Mercalli scale
9. Seismic belts
10. Locating an epicenter
11. Tsunami
12. Seismic risk-history, seismic gap
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