Introduction: earthquakes shake our planet every day. Often, the quakes cause little damage and no loss of life; but that is not always the situation. Understanding what is going on can make an earthquake a little less threatening. Also, today, we can construct homes that are likely to survive a moderate quake. Like other exercises, this one has two main parts.
I. Place your answers on lines along the left margin.
A. Read the following are true or false. Place a T or F on the line.
_____ 1. Most earthquake deaths occur because buildings collapse or tsunamis flood
an area.
_____ 2. Plate movements produce all earthquakes.
_____ 3. Most faults occur along plate boundaries.
_____ 4. Faults are classified according to the relative movements of rocks on either
side of the fault plane.
_____ 5. Repeated movements on a fault or series of faults has little effect on the
land.
_____ 6. Each type of plate boundary is characterized by a specific type of fault.
_____ 7. The forces involved in plate tectonics are equally spread along the entire
length of a fault.
_____ 8. Small fault movements can produce large earthquakes.
_____ 9. All earthquakes are caused by motions on faults.
_____ 10. A megathrust is a long fault that is hundreds or thousands of kilometers
long. Movement along such a fault may destroy large cities.
_____ 11. Megathrust earthquakes on the Cascadia subduction zone occur frequently.
_____ 12. Prior to a fault moving, rocks adjacent to the fault are never deformed.
_____ 13. Since the Jones family bought a home in what is known as a seismic gap,
they do not need to ever expect a quake.
_____ 14. In the U. S., only the west coast is likely to experience earthquakes.
_____ 15. Seismic waves move away from the earthquake’s focus.
_____ 16. Body earthquake waves cause most building destruction.
_____ 17. P waves move faster than S waves.
_____ 18. S waves might be thought of as shake waves and P waves are like push
waves.
_____ 19. P waves cannot pass through liquids.
_____ 20. Data from one seismograph station is enough to determine where a quake
occurred.
_____ 21. Animals seem to sense when an earthquake is likely to occur.
_____ 22. Earthquake magnitude is measured on a logarithmic scale in which each
division represents a 10-fold increase in the ground motion.
_____ 23. The longer the fault rupture, the smaller the earthquake.
_____ 24. The Modified Mercalli scale is based on the amount of damage, but the
amount of damage depends on factors other than the earthquake itself.
B. Select the word that best completes the following statements from helpful
words. You may use these words as often as needed.
Helpful Words: aftershocks, Wadati-Benihoff, body, epicenter, faults, focus, induced, landslides, liquefaction, magma, magnitudes, plane, scarp, seismographs, strike, surface, ten, trenches, triangulation, tsunamis.
_____________ 1. In the __________ zone, earthquakes define the descending plate
as it moves deeper into the planet.
_____________ 2. _______ are zones of weakness in Earth’s crust.
_____________ 3. _______ earthquakes are caused when human activities activate
old faults.
_____________ 4. _______ are instruments that record seismic waves.
_____________ 5. Earthquakes may cause _________, huge, dangerous waves
.
_____________ 6. _______ are fractures in the ground along which movement has
occurred.
_____________ 7. The location on a fault where the break begins (= the earthquake
source) is called the ______.
_____________ 8. The _______ is the geographic location on Earth’s surface directly
above the earthquake focus.
_____________ 9. The fault _____ is the up-thrown side of the fault.
_____________10. The fault _______ is the surface along which the slip or movement
occurs during an earthquake.
_____________11. The _______ of the fault is the trace of the fault on a horizontal
plane.
_____________12. Two types of earthquake waves are _____ waves and surface
waves.
_____________13. _________ waves include P and S waves.
_____________14. _________ waves include Rayleigh waves and Love waves.
_____________15. The site where an earthquake occurs is located by a process called
________.
_____________16. The shaking and energy released from different earthquakes can
be compared by using earthquake ______.
_____________17. Earthquake magnitude is measured on a logarithmic scale so each
division represents a _____ fold increase in ground motion.
_____________18. ___________ are quakes that occur on the same or nearby faults
after the main shock.
_____________19. ________ may occur following an earthquake when soil, rocks, and
materials forming the slope is activated by the shaking.
_____________20. _________ occurs when shaking of the ground causes compaction
of the sediment forcing water to the surface.
_____________21. A ________ is a series of large waves created by an earthquake, meteor impact, or massive landslide that enters a body of water.
II. Answer the following as indicated.
Name the designated sites. Helpful words: Angle of dip, epicenter, fault, focus, scarp, strike.
1
2
6
5
4
3
B. Two earthquakes of the same magnitude occurred in two different areas
with the same number of people. One quake damaged most of the
buildings and killed many people. The other quake damaged few
buildings and killed no one. List six factors that could account for the
difference.
1. ____________________________________________________________
2. ____________________________________________________________
3. ____________________________________________________________
4. ____________________________________________________________
5. ____________________________________________________________
6. ____________________________________________________________
C. Explain how earthquake waves helped scientists understand Earth’s layers and
the difference between the layers.
D. Explain how researchers locate the epicenter of an earthquake.
E. Go to https://earthquake.usgs.gov/earthquakes/map/ and examine the map.
Which country has the most earthquakes?
