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Inside Earth Chapter 2: Earthquakes Notes
Section 1: Earth’s Crust in Motion
1.
How Do Stress Forces Affect Rock?
a. The movement of earth’s ________________creates powerful forces that squeeze or pull the
rock in the crust – these forces are examples of stress
b. ______________– a force that acts on rock to change its shape or volume
c. An _____________________is the shaking and trembling that results from the movement of rock
beneath earth’s surface
2.
How Does Stress Effect the Earth’s Crust?
a. _______________________– any change in the volume or shape or earth’s crust
b. Three kinds of stress in the crust:
i. ____________________– stress that pushes a mass of rock in two opposite directions
ii. __________________– pulls on the crust, stretching rock so that it becomes thinner in the
middle like warm bubble gum
iii. ___________________– squeezes rock until it folds or breaks like a giant trash compactor
3.
What Is a Fault?
a. _________________– a break in earth’s ________________where slabs of crust slip past each
other; These usually occur at plate boundaries
4.
What Kind of Faults Are There?
a. Three Kinds:
i. _________________________
ii. _________________________
iii. _________________________
5.
What Are Strike-slip Faults?
a. Strike-slip faults
i. __________________forces cause rocks to slip past each other ______________with little
________and ____________Motion
ii. Ex. San Andreas fault in California
6.
What Are Normal Faults?
a. Normal faults
i. _________________forces cause the rocks to form the fault at an _____________
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ii. One block is above the fault
iii. ________________wall – the half of the fault that lies above
iv. ________________– the half of the fault that lies below
v. Ex. Rio Grande rift valley
7.
What Are Reverse Faults?
a. Reverse faults
i. _________________________forces cause the rocks to move _______________each
other
ii. Same structure as normal fault but the blocks move in opposite direction; hanging wall
move up
iii. Ex. Appalachian Mountains and Mount Gould in Glacier National Park
8.
Identify the faults shown.
9.
How Are Mountains Effected by These Forces?
a. ______________________mountains – normal faults uplift a block of rock
b. ____________________– bends in the rock that form when compression shortens and thickens
part of the earth’s crust. Ex. Himalayas
10.
How Are Mountains Effected by These Forces? (Continued)
a. ____________________– a fold upward into an arch
b. ____________________– a fold downward into an arch
c. ____________________– a large area of flat land elevated high above sea level
Section 2: Measuring Earthquakes
11.
How Does the Energy of an Earthquake Travel Through Earth?
a. ____________________– most begin in the lithosphere
b. ________________– the point beneath the earth’s surface where rock that is under stress
breaks, triggering an earthquake
c. ________________– the point on the earth’s surface directly above the focus
12.
What Are Seismic Waves?
a. __________________________ – vibrations that travel through Earth carrying the energy
released during an earthquake
i. They move like ripples on a pond
ii. They carry the energy of an earthquake away from the focus, through Earth’s interior, and
across the surface
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iii. The energy is greatest the ___________________
13.
What Are the Different Kinds of Seismic Waves?
a. Three categories:
i. _____________
ii. _____________
iii. _____________
b. P waves and S waves are sent out from the______________; Surface waves develop when the
waves reach the _______________
14.
What Are P Waves?
a. P waves are ________________waves
i. The ______________waves to arrive
ii. Earthquake waves that ____________________and expand the ground like an accordion
iii. Cause buildings to contract and expand
15.
What Are S Waves?
a. S waves are _______________________waves
i. Earthquake waves that vibrate from side to side as well as up and down
ii. These waves shake the ground _____________and ____________
iii. Shake structures violently
iv. ___________________move through liquids
16.
What Are Surface Waves?
a. When P waves and S waves reach the surface some are transformed into surface waves
i. Surface waves move more ________________than P waves and S waves
ii. Produce the most ________________ground movements
iii. Can make the ground roll like ocean waves or shake buildings from side to side
Section 3: Monitoring Earthquakes
17. How Do Scientists Detect Seismic Waves?
a. ____________________________– records the ground ______________________caused by
seismic waves as they move through the Earth
18.
How Do Scientists Measure Earthquakes?
a. There are at least 20 different measures for rating earthquakes, three are:
i. ______________
ii. ______________
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iii. ___________________ _________________
b. _______________________– a measurement of earthquake strength based on seismic waves
19.
What Is the Mercalli Scale?
a. Rated earthquakes according to their _________________
i. _______________: strength of ground motion in a given place
b. Not a precise measurement
c. Describes how earthquakes affect people, buildings, and the land surface
20.
What Is the Richter Scale?
a. A rating of the ______________of _______________waves as measured by a particular type of
seismograph
b. Accurate measurements for small, nearby earthquakes not large, distant earthquakes
21.
What Is the Moment Magnitude?
a. A _______________system that estimates the total ______________released by an earthquake
b. Can be used to rate earthquakes of all sizes, near or far
c. Below _______ – little damage
d. Above 5.0 – great destruction
22.
How Do Scientists Locate the Epicenter?
a. Geologists use ________________waves
i. P waves arrive first
ii. S waves arrive close behind
iii. Scientist measure the _________________in arrival times
1. The farther away an earthquake is the greater the time between their arrival
iv. Scientists draw three circles using data from seismographs set at different stations to see
where they intersect – the epicenter
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