UNIT 4 LESSON 6 – MEASURING EARTHQUAKE WAVES (pgs. 252-265)
1. An earthquake occurs when _______________________ of rock move ______________________and release
_______________________. The energy travels through rock as ___________________________.
2. Earth’s lithosphere is the ________________________ outer _______________________ of Earth that includes the
___________________________________.
3. The steps to the formation of an earthquake:
1. Stress causes ____________________________ to form.
2. A fault is a ______________________________ in rock along which one block ___________________ relative
to the other.
3. Stress causes rocks to deform, when rocks deform, or _____________________________ their original shape.
4. If stress becomes too great, rocks along the fault will ______________________ and
_________________________.
5. Once rocks break, the pieces of broken rock return to an ____________________________________ shape.
This is called elastic rebound.
6. When rocks along the _________________________ break and move along the
fault,_________________________ is released into the surrounding rock in the form of
_______________________________.
7. This process causes _______________________________________.
4. Focus is the place where the first ____________________________ of an earthquake takes place.
5. Epicenter – is the point on Earth’s ____________________________ directly above the focus.
6. Seismic waves – are ____________________ or shock waves released from the focus that cause ground motion.
7. Body waves – waves that travel through the Earth’s _________________________
.
8. Surface waves – only travel along the _____________________ not through the Earth.
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9. Review the 3 types of seismic waves:
P waves (primary)
S waves (secondary)
L waves (surface)
Speed (relative
to each other)
Motion of rock
Can travel
through…
(solid, liquid, gas)
Body wave or
surface wave
10. Seismometers are used to ___________________________ seismic waves. They are located at
_______________________________________stations.
11. Seismogram is a ______________________________ of earthquake motion. They also ______________________
the arrival times of __________________________________ waves.
12. How is an earthquakes epicenter located?
Scientists measure the difference between the arrival times between the ___________ and ___________waves.
The farther away the earthquake is the _______________________________ the time between the arrival of
the P waves and S waves.
13. The epicenter is located by drawing ____________________ circles using the data. Where all 3 circles meet is where
the ___________________________________ is.
14. Magnitude is the measure of the ___________________________ released by and earthquake.
The _____________________________ the magnitude the ______________________ the earthquake.
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The magnitude is measured in two ways.
1. Richter scale measures the ___________________ motion from an earthquake to find the
earthquakes __________________________________.
2. Moment Magnitude scale measures earthquake _____________________________ based on the
__________________________ of the area of the fault that ____________________and the
__________________________________(hardness) of the rocks in the fault. The MM scale is more
_______________________________ for __________________________ earthquakes than the Richter
scale is.
15 Intensity is the __________________________ (damage done)of an earthquake and how the earthquake is
_________________ by people.
The intensity is measured by the ________________________________ scale.
16. What factors determine the effects of an earthquake?
1. Magnitude (explain) – stronger _________________________ produce more ______________________
movement.
2. Local geology
a. solid rock does not __________________________ the ground movement.
b. Loose soil saturated with water (liquefaction) can cause the earthquake to be more
__________________________________. The moist soil turns into a liquid mud.
c. Distance from the epicenter - the farther from the epicenter the less _______________________
the waves carry and the less dangerous the seismic waves are.
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3. Building construction
a. Building material needs to be more _________________________________ . For example,
use ______________________________ and __________________________________.
d. Base isolators act as ____________________________________ during an earthquake. They
are made of layers of _______________________________ and _____________________________
wrapped around a __________________________ core. They prevent the ________________________
seismic waves from traveling through the ________________________________.
4. Population of the area is important. The _______________________ people that live in an area the
__________________________ damage and deaths occur.
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