Earth Systems Science Final Fall 24
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1. What is an earthquake? Under what circumstances do most large earth-
quakes occur? Explain why and how earthquakes occur, according to the elastic
rebound hypothesis. Why is there an upper limit on the intensity of earth-
quakes?: An earthquake is a sudden shaking of the ground, caused by the movement of tectonic plates or the
release of stress in the Earth's crust. Most large earthquakes occur along faults, especially at plate boundaries, like
subduction zones, transform faults, and rifting zones.
The elastic rebound hypothesis explains earthquakes by suggesting that stress builds up in the crust due to plate
movement. When the stress exceeds the strength of the rocks, they rupture and release energy as seismic waves.
Afterward, the rocks "snap back" to their original shape.
There's an upper limit to earthquake intensity because of the strength of rocks and the size of faults. Once the stress
exceeds the rock's strength, it ruptures, and there's a physical limit to how much stress can accumulate before this
happens.
2. What is the relationship between an earthquake's focus and its epicenter?: The
focus is the point inside Earth where an earthquake starts, and the epicenter is the point on the surface directly above
it.
3. How are faults, hypocenters, and epicenters related?: A fault is a fracture where rocks
move, the hypocenter is the point inside Earth where an earthquake starts, and the epicenter is directly above it on the
surface.
4. How are seismic waves recorded and measured? What is the difference be-
tween a seismograph and a seismogram? Describe the principle of a seismo-
graph.: A seismograph detects ground motion, and a seismogram is the recorded wave pattern. It works on the
principle of inertia, where a stationary mass moves relative to the ground.
5. How do scientists use seismic waves to determine the location of an earth-
quake? Describe the process.: P-waves (faster) and S-waves (slower) reaching seismographs to calculate
the distance to the earthquake.
6. What type of faults tend to produce the most destructive earthquakes?: Reverse
faults and thrust faults, common at convergent boundaries, tend to produce the most destructive earthquakes due to
the large amounts of energy released.
7. Describe the important features of the Richter magnitude scale, the seismic
moment magnitude scale, and the modified Mercalli intensity scale, and com-
ment on the differences between them.: The Richter scale measures magnitude based on seismic
, Earth Systems Science Final Fall 24
Study online at https://quizlet.com/_hvxi6h
wave amplitude, suited for small quakes. The seismic moment magnitude scale measures total energy released, for al
quake sizes. The Modified Mercalli scale assesses earthquake effects on people and structures.
8. What are reflection and refraction, and how do they help scientists determine
what's insterm-6ide Earth?: Reflection occurs when seismic waves bounce off boundaries, and refraction
happens when they bend as they pass through different materials.
9. How did Earth acquire its layered structure?: Earth's layered structure formed during its early
molten state, when denser materials sank to form the core, and lighter materials rose to form the mantle and crust
through a process called differentiation.
10. Briefly describe how seismic waves are used to probe Earth's interior: Seismic
waves change speed and direction based on the materials they pass through. By analyzing their reflection and refraction,
scientists can map Earth's layers and determine their composition.
11. How do continental crustal and oceanic crust differ?: Continental crust is thicker, less
dense, and made mostly of granite, while oceanic crust is thinner, denser, and primarily composed of basalt.
12. Contrast the physical makeup of the asthenosphere and the lithosphere: The
lithosphere is rigid, brittle, and includes the Earth's crust and uppermost mantle. The asthenosphere is softer, more
ductile, and located beneath the lithosphere, allowing it to flow slowly.
13. How are Earth's inner and outer cores different? How are they similar?: The
inner core is solid, made of iron and nickel, due to high pressure, while the outer core is liquid, also composed of iron
and nickel, because of lower pressure. Both are at Earth's center.
14. Earthquakes can cause damage in many ways; name and briefly describe
four or more.: Shaking: Damages buildings.
Surface Rupture: Cracks the ground.
Liquefaction: Buildings sink.
Tsunamis: Coastal flooding.
Landslides: Triggered by shaking.
15. Can scientists predict when and where earthquakes will occur? How can
scientists forecast earthquakes?: Scientists cannot predict exact times or locations of earthquakes.
However, they can forecast earthquake likelihood based on fault zones, historical data, and seismic activity patterns.
16. List the major differences between P. S. and surface waves: P-waves: Fastest, travel
through solids and liquids, compressional motion.
S-waves: Slower, travel only through solids, shear motion.
Surface waves: Slowest, travel along Earth's surface, cause most damage.
, Earth Systems Science Final Fall 24
Study online at https://quizlet.com/_hvxi6h
17. How have scientists used earthquakes to determine the dimensions of tec-
tonic plates and the characteristics of tectonic processes such as subduction?-
: Scientists use earthquake data to map plate boundaries, study seismic wave patterns, and identify subduction zones,
revealing tectonic processes like plate movement and convergence.
18. What affects the velocities of seismic waves?: Seismic wave velocities are affected by materia
composition, density, and temperature. Waves travel faster through denser, more rigid materials and slower through
less dense or more fluid ones.
19. Which type of seismic waves tend to cause the greatest destruction to
buildings?: Surface waves tend to cause the greatest destruction to buildings due to their slower speed and larger
amplitude, leading to stronger ground motion.
20. What information does a travel-time graph provide?: A travel-time graph shows the time
it takes for seismic waves to travel different distances, helping scientists determine the location of an earthquake's
epicenter and the properties of Earth's interior.
21. Briefly describe the triangulation method used to determine the epicenter of
an earthquake.: The triangulation method uses data from at least three seismograph stations. By measuring
the time difference between P- and S-waves, the distance to the epicenter is calculated. The epicenter is located where
the three distance circles intersect.
22. How much more energy does a magnitude 7.0 earthquake release than a
6.0 earthquake?: A magnitude 7.0 earthquake releases about 32 times more energy than a magnitude 6.0
earthquake, as the energy increases by a factor of roughly 32 for each whole number on the Richter scale.
23. Why is the moment magnitude scale favored over the Richter scale?: The moment
magnitude scale is preferred because it accurately measures large earthquakes and accounts for total energy, fault size,
and movement, unlike the Richter scale, which is less precise for big quakes.
24. Where does the greatest amount of seismic activity occur?: Ring of Fire, a zone of
tectonic plate boundaries around the Pacific Ocean, where most earthquakes and volcanic eruptions happen.
25. What type of plate boundary is associated with Earth's largest earthquakes?-
: Convergent plate boundaries are associated with Earth's largest earthquakes, especially in subduction zones, where
one plate is forced beneath another.
26. What is the difference between magma and lava? What is the difference
between pyroclasts and tephra?: Magma is molten rock beneath Earth's surface, while lava is magma
that has erupted onto the surface.
Study online at https://quizlet.com/_hvxi6h
1. What is an earthquake? Under what circumstances do most large earth-
quakes occur? Explain why and how earthquakes occur, according to the elastic
rebound hypothesis. Why is there an upper limit on the intensity of earth-
quakes?: An earthquake is a sudden shaking of the ground, caused by the movement of tectonic plates or the
release of stress in the Earth's crust. Most large earthquakes occur along faults, especially at plate boundaries, like
subduction zones, transform faults, and rifting zones.
The elastic rebound hypothesis explains earthquakes by suggesting that stress builds up in the crust due to plate
movement. When the stress exceeds the strength of the rocks, they rupture and release energy as seismic waves.
Afterward, the rocks "snap back" to their original shape.
There's an upper limit to earthquake intensity because of the strength of rocks and the size of faults. Once the stress
exceeds the rock's strength, it ruptures, and there's a physical limit to how much stress can accumulate before this
happens.
2. What is the relationship between an earthquake's focus and its epicenter?: The
focus is the point inside Earth where an earthquake starts, and the epicenter is the point on the surface directly above
it.
3. How are faults, hypocenters, and epicenters related?: A fault is a fracture where rocks
move, the hypocenter is the point inside Earth where an earthquake starts, and the epicenter is directly above it on the
surface.
4. How are seismic waves recorded and measured? What is the difference be-
tween a seismograph and a seismogram? Describe the principle of a seismo-
graph.: A seismograph detects ground motion, and a seismogram is the recorded wave pattern. It works on the
principle of inertia, where a stationary mass moves relative to the ground.
5. How do scientists use seismic waves to determine the location of an earth-
quake? Describe the process.: P-waves (faster) and S-waves (slower) reaching seismographs to calculate
the distance to the earthquake.
6. What type of faults tend to produce the most destructive earthquakes?: Reverse
faults and thrust faults, common at convergent boundaries, tend to produce the most destructive earthquakes due to
the large amounts of energy released.
7. Describe the important features of the Richter magnitude scale, the seismic
moment magnitude scale, and the modified Mercalli intensity scale, and com-
ment on the differences between them.: The Richter scale measures magnitude based on seismic
, Earth Systems Science Final Fall 24
Study online at https://quizlet.com/_hvxi6h
wave amplitude, suited for small quakes. The seismic moment magnitude scale measures total energy released, for al
quake sizes. The Modified Mercalli scale assesses earthquake effects on people and structures.
8. What are reflection and refraction, and how do they help scientists determine
what's insterm-6ide Earth?: Reflection occurs when seismic waves bounce off boundaries, and refraction
happens when they bend as they pass through different materials.
9. How did Earth acquire its layered structure?: Earth's layered structure formed during its early
molten state, when denser materials sank to form the core, and lighter materials rose to form the mantle and crust
through a process called differentiation.
10. Briefly describe how seismic waves are used to probe Earth's interior: Seismic
waves change speed and direction based on the materials they pass through. By analyzing their reflection and refraction,
scientists can map Earth's layers and determine their composition.
11. How do continental crustal and oceanic crust differ?: Continental crust is thicker, less
dense, and made mostly of granite, while oceanic crust is thinner, denser, and primarily composed of basalt.
12. Contrast the physical makeup of the asthenosphere and the lithosphere: The
lithosphere is rigid, brittle, and includes the Earth's crust and uppermost mantle. The asthenosphere is softer, more
ductile, and located beneath the lithosphere, allowing it to flow slowly.
13. How are Earth's inner and outer cores different? How are they similar?: The
inner core is solid, made of iron and nickel, due to high pressure, while the outer core is liquid, also composed of iron
and nickel, because of lower pressure. Both are at Earth's center.
14. Earthquakes can cause damage in many ways; name and briefly describe
four or more.: Shaking: Damages buildings.
Surface Rupture: Cracks the ground.
Liquefaction: Buildings sink.
Tsunamis: Coastal flooding.
Landslides: Triggered by shaking.
15. Can scientists predict when and where earthquakes will occur? How can
scientists forecast earthquakes?: Scientists cannot predict exact times or locations of earthquakes.
However, they can forecast earthquake likelihood based on fault zones, historical data, and seismic activity patterns.
16. List the major differences between P. S. and surface waves: P-waves: Fastest, travel
through solids and liquids, compressional motion.
S-waves: Slower, travel only through solids, shear motion.
Surface waves: Slowest, travel along Earth's surface, cause most damage.
, Earth Systems Science Final Fall 24
Study online at https://quizlet.com/_hvxi6h
17. How have scientists used earthquakes to determine the dimensions of tec-
tonic plates and the characteristics of tectonic processes such as subduction?-
: Scientists use earthquake data to map plate boundaries, study seismic wave patterns, and identify subduction zones,
revealing tectonic processes like plate movement and convergence.
18. What affects the velocities of seismic waves?: Seismic wave velocities are affected by materia
composition, density, and temperature. Waves travel faster through denser, more rigid materials and slower through
less dense or more fluid ones.
19. Which type of seismic waves tend to cause the greatest destruction to
buildings?: Surface waves tend to cause the greatest destruction to buildings due to their slower speed and larger
amplitude, leading to stronger ground motion.
20. What information does a travel-time graph provide?: A travel-time graph shows the time
it takes for seismic waves to travel different distances, helping scientists determine the location of an earthquake's
epicenter and the properties of Earth's interior.
21. Briefly describe the triangulation method used to determine the epicenter of
an earthquake.: The triangulation method uses data from at least three seismograph stations. By measuring
the time difference between P- and S-waves, the distance to the epicenter is calculated. The epicenter is located where
the three distance circles intersect.
22. How much more energy does a magnitude 7.0 earthquake release than a
6.0 earthquake?: A magnitude 7.0 earthquake releases about 32 times more energy than a magnitude 6.0
earthquake, as the energy increases by a factor of roughly 32 for each whole number on the Richter scale.
23. Why is the moment magnitude scale favored over the Richter scale?: The moment
magnitude scale is preferred because it accurately measures large earthquakes and accounts for total energy, fault size,
and movement, unlike the Richter scale, which is less precise for big quakes.
24. Where does the greatest amount of seismic activity occur?: Ring of Fire, a zone of
tectonic plate boundaries around the Pacific Ocean, where most earthquakes and volcanic eruptions happen.
25. What type of plate boundary is associated with Earth's largest earthquakes?-
: Convergent plate boundaries are associated with Earth's largest earthquakes, especially in subduction zones, where
one plate is forced beneath another.
26. What is the difference between magma and lava? What is the difference
between pyroclasts and tephra?: Magma is molten rock beneath Earth's surface, while lava is magma
that has erupted onto the surface.
