ICS 1 Semester 1 Block 3 9/12-9/24 Day 1 Earthquakes
Standard(s): ES 3. d. Students know why and how earthquakes occur and the scales used to measure their intensity and
magnitude.
Objective (s): Earthquakes are caused by lithospheric plates moving against each other. The magnitude of an earthquake is a
measure of the amplitude of an earthquake’s waves. An earthquake’s intensity is a subjective measure of how strong an
earthquake felt and how much damage it did at any given location.
Ch 3 Earthquakes Pg. 122 -175
p.127-130 12 vocab check your understanding 1-5
p136-138 2 vocab check your understanding 1-4
p.143-146 0 vocab check your understanding 1-5
p.152-153 4 vocab check your understanding 1, 2
p.163-164 2 vocab check your understanding 1-4
p.172-173 1 vocab check your understanding 1-6
p.127-130
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Earthquake: Sudden change in Pressure which causes shaking, release of strain
Seismic wave: General term for all elastic waves b EQ.
Fault: A fracture zone or area along which rock masses have moved and are not Parallel.
Shear Strength: The shear force needed to break a solid material
Elastic rebound: The return of bent elastic solid to its relaxed state
Friction: Force between to objects that have a common point.
Focus: Point underground were Pressure is released and EQ starts
Epicenter: Point on the ground were EQ originally came from (above focus)
Fault Scarp: Cliff formed by a fault that reaches the Earth’s Surface.
Primary Wave: Compression wave
Secondary wave: Wiggle wave, Shear wave
Surface wave: a seismic wave that travels on Surface
p.136-138
13. Seismometer: an instrument that measures seismic waves. Signal from electrical voltage
14. Seismogram: the record made by a seismometer
p.143-146
0 vocabulary
p.152-153
15. Transform fault-a vertical surface of slippage between two lithospheric plates along an offset between two segments of a
spreading apart
16. Subduction zone-long narrow belt which one plate goes under another
17. Risk-the potential impact of natural hazard on people or property
18. Hazard-a natural event like an earthquake that has the potential to do damage or harm
p.163-164
19. Isoseismal map-a map showing the lines connecting points on the Earth’s surface at which earthquake intensity is the same
20. Tsunami: a great sea wave produced by a submarine earthquake( or volcanic eruption or landslide)
21. Resonance: a condition in which a vibration affecting an object has about the same period as the natural vibration period
of the object
p.130 1-5
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An earthquake is: Release of Pressure
Seismic waves are generated by: Shear force builds up until its released
The Focus is underground and the epicenter is aboveground
Primary wave like traffic, Secondary wave like a rollercoaster, surface wave
like a water wave. Like pictures on p.130
Surface wave is fastest then Primary, Secondary.
p.138 1-5
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Seismometer measures the magnitude of seismic waves.
a) You need 3 seismometers x, y, z direction to have an accurate reading.
b) The seismometers should be oriented such that 2 horizontal at right angles from each other, 1 vertical at a right angle
from the other two.
The seismogram is the graph created by a seismometer
The distance from the epicenter is measured with a travel time curve
p.146 1-5
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Magnitude versus intensity for a nonscientist, intensity tells the type of damage.
2. A. intensity of 4 = swinging things
B. Intensity of 3 = things vibrating but not that much
C. intensity of 6 = bells ring
3. The epicenter is where the Earthquake started on the surface. Not all ways the most shaking because vibrations can be
magnified as they travel
4. Type of rock, water, soil content all effect the vibrations felt by an Earthquake
5. Earthquake magnitude scale measures energy.
p. 153-154
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Earthquakes are evidence to support the theory of plate tectonics because
they happen along plate boundaries.
The highest risk of Earthquakes happens along plate boundaries or fault lines
P.163-164
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Hazards from an Earthquake are: falling thingy’s, electric shock from wires, ground ruptures, collapsing structures, etc…
Fires cause damage by …
A tsunami is a huge wave of water
Tsunami damage is difficult to predict because it pushes and pulls on objects
p. 172-173
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Earthquakes can break gas, water power lines and fires, floods and electrocution can occur.
The five factors that are responsible for Earthquake damage are: Duration of shaking, Direction of Motion, Underlying Earth
materials, Resonance, Materials
The Northridge earthquake caused damage to building because The buildings didn’t have protection from the strong
vertical motion
The wet soil of the coast can be easily moved compared to the solid bedrock During an earthquake.
Filled land is not as hard as bedrock so during an Earthquake more motion Occurs.
In the 1985, Mexico city Earthquake the tall building made the ground Vibrations amplified.