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Earthquakes
Standard 1d
p. 88,90,166-71,186-87,192-204,208-09
1. What are earthquakes
a. Seismology is the study of earthquakes
b. Most earthquakes take place near the edges of tectonic plates.
i. Faults are large cracks in the earths crust
1. Earthquakes take place along these faults.
a. Because of the sliding of the faults.
2. What causes earthquakes
a. As tectonic plates push, pull and slide, stress builds up along the faults.
i. Rock along the faults bend and fold.
1. called deformation
3. Are all earthquakes the same?
a. Earthquakes differ by
i. Strength
ii. Depth
b. The differences are caused by the type of tectonic plate motion
Plate motion Prominent fault type
Characteristics
Transform
strike-slip
moderate/shallow
Convergent
reverse fault
strong/deep
Divergent
normal
weak/shallow
4. How do earthquakes travel?
a. Seismic waves
i. P wave
1. causes by rock being compressed or stretched
2. P stands for Primary
a. Fastest waves
b. Travel through solids, liquids
and gases
c. Moves rock back and forth
between an stretched and
compressed position
b. S waves
i. Can not travel through materials that are completely liquid
ii. Shear rock back and forth
Earthquakes
Standard 1g
p. 168-69, 172-74, 177-78, 181, 186-87, 240
1. Locating earthquakes
a. Seismographs
i. Instruments located near the surface of the
earth
ii. They record seismic waves
iii. The seismograph creates a seismogram (p.
172)
iv. Used to measure motion of the earth
b. Also used to find the epicenter
i. This is the point on the surface, directly
above the quake
c. Focus
i. Is the point inside the earth where the
earthquake begins.
d. Finding the epicenter
i. S-P time method
1. This is done by comparing readings of
different seismograms of the same
quake from all over the world.
2. p. 173
2. Measuring earthquake strength
a. Richter Scale
i. Measures the amount of energy released by
the quake.
ii. A scale of 1-10 is used
iii. An earthquake of 5.0 is 31.7 times stronger
than an earthquake of 4.0