EARTHQUAKES AND EARTHQUAKE 11
HAZARDS
INTRODUCTION
Earthquakes and Earthquake Hazards
CHAPTER OUTLINE
1.
2.
3.
4.
5.
6.
7.
LEARNING OBJECTIVES/FOCUS ON CONCEPTS
11.1 Sketch and describe
11.3 Compare and contrast describe
,
TEACHING STRATEGIES
Clicker Questions:
Muddiest Point:
TEACHER RESOURCES
Web Resources:
Tsunami Resources
Centers
oIncorporated Research Institutions for Seismology (IRIS)
Learning Resources
o SERC Site Guide: Earthquakes
Specific Earthquake Examples:
Seismic Zones
Imagery, Videos, and Animations:
Images
Videos
Animations
Richter Scale Interactive Animation
ANSWERS TO QUESTIONS IN THE CHAPTER:
CONCEPT CHECKS
11.1 WHAT IS AN EARTHQUAKE?
1. An earthquake is ground shaking caused by a sudden release of energy from the slipping of
2. Faults are fractures in Earths crust along which the slippage occurs and causes earthquakes.
3. H.F. Reid was the first geologist to explain the mechanism by which most earthquakes are
4. Stress along a fault causes rocks to build up elastic energy by bending (but not breaking).
11.2 FAULTS AND EARTHQUAKES
1. The most destructive earthquakes are formed along a type of reverse fault called a megathrust
2. False. Faults do not slip all at once; rather, the initial slip begins at the hypocenter and travels
3. This statement is likely false. Fault creep is a means by which strain is released along a fault in
11.3 SEISMOLOGY: THE STUDY OF EARTHQUAKE WAVES
1. A seismograph is designed to measure the amount of displacement (horizontal and/or
2. P- and S-waves are body waves that travel through the Earths crust. P-waves are primary
waves (they arrive first at a recording station) and move Earth materials in a push-pull
3. The greatest destruction of earthquakes occurs with surface waves. Surface waves have the
11.4 DETERMINING THE SIZE OF EARTHQUAKES
1. The Modified Mercalli Intensity scale is a measurement of the amount of shaking an
2. The lower portions of the Modified Mercalli Intensity scale are based on how the earthquake
3. A magnitude 7.0 earthquake releases 32 times more energy than a magnitude 6.0 earthquake.
4. The Richter scale cannot easily distinguish very large earthquakes. Moment magnitude
11.5 EARTHQUAKE DESTRUCTION
1. Four factors that influence the amount of damage to human structures in an earthquake
2. Other types of destruction associated with earthquakes include liquefaction, landslides and
ground subsidence, fires, seiche, and tsunami.
3. A tsunami is a very large ocean wave created by displacement of the seafloor either from an
4. If the 7.0 magnitude earthquake occurs in a more populated region with buildings not built to
withstand shaking, it will cause more destruction than an 8.0 magnitude earthquake in a less
11.6 EARTHQUAKE BELTS AND PLATE BOUNDARIES
1. The greatest amount of seismic activity occurs in the circum-Pacific belt. In this belt, active
2. The largest earthquakes on Earth are associated with convergent plate boundaries
11.6 CAN AN EARTHQUAKE BE PREDICTED?
1. Accurate short-term earthquake predictions are not currently possible because current
measurements of precursorsground elevation changes, variations in strain levels, changes in
groundwater levels, and even anomalous animal activityall have led to false alarms and/or
2. Long-range earthquake predictions, supported by historical data and paleoseismic data, help
us to know where large earthquakes may occur. This knowledge assists in building code
practices as well as land use planning.
EYE ON EARTH
EOE #1 CALVERAS FAULT
1. The slow slippage of a fault over time is called fault creep.
2. In fault creep, energy is slowly dissipated over time in a series of small earthquakes.
Because energy does not build up in fault creep, major earthquakes are uncommon.
EOE #2 SOIL LIQUEFACTION
1. If a structure is built on sandy soil that suddenly experiences liquefaction, that buildings
GIVE IT SOME THOUGHT
1. Students should draw some type of figure similar to that of Figure 11.4 in the textbook.
Students might describe elastic rebound as similar to bending a stick or pencil: as elastic stress
3.
a. The P-wave arrived first.
4. The water you see in your footprint is water that is packed between the sand grains of the
5. Student drawing should indicate that water is pulled from the shoreline to build up very large
waves as the tsunami reaches shore. The water moving into wave height causes a withdrawal
of water at the shore.
6. A tsunami is a secondary effect due to the displacement of seawater by ground displacement in
an earthquake. Once a tsunami is initiated, it travels across the ocean at speeds of several
value to coastlines at or very near the earthquake epicenter because the tsunami would arrive
relatively quickly to these locations.
7.
a. The segment labeled (2) likely experiences fault creep because it shows no evidence of
producing a major quake in the past. This suggests that strain is gradually dissipated
from this segment in a series of very small earthquakes over time.
b. Segment 3 last produced a quake in 1857. If this segment produces earthquakes every
135 years, we would have expected the next earthquake to occur in 1992. This did not
8.
a. The bedrock experienced the least amount of shaking.
b. The soft mud experienced the greatest amount of shaking.
c. Section #1 of the Cypress Viaduct likely collapsed because it was supported by soft
9.
a. Chapter 10 calls this feature a sag pond.
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