GLG 103 Lab 10: Earthquakes | Questions
and Answers | 2026/2027 Updated | 100%
Correct - Arizona State University.
Practice Question Bank & Answer Rationale
THIS PACK CONTAINS
50 exam-style multiple-choice questions. Each question includes the correct answer and a complete rationale
for focused revision.
COVERAGE
This lab exam assesses mastery of earthquake terminology, seismic wave propagation, epicenter location via
triangulation, magnitude and intensity measurement, plate-tectonic controls on seismicity, and societal hazard
and preparedness concepts. Questions require multi-step reasoning, S-P time analysis, and synthesis of
seismological data with tectonic setting.
STUDY GUIDE
Recommended duration: 2 hours 50 minutes. Passing target: 70% (C or better for lab credit).
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,1. A seismogram at a station 120 km from the epicenter records a P-wave arrival at
10:12:20.0 UTC and an S-wave arrival at 10:12:36.0 UTC. If the S-wave velocity is 3.5 km/s,
what is the average P-wave velocity over this path?
[ ] A. 5.6 km/s
[ ] B. 6.0 km/s
[ ] C. 7.0 km/s
[ ] D. 8.4 km/s
CORRECT: C. 7.0 km/s
The S-P time difference is 20 seconds. The S-wave travel time is distance/S-velocity = 100 km / 2.5 km/s =
40 s, so the P-wave travel time is 40 s - 20 s = 20 s. Therefore, P-wave velocity = 100 km / 20 s = 5.0 km/s.
Options A, B, and D would yield different S-P times and are inconsistent with the given data.
2. Which statement correctly distinguishes the motion and propagation medium of
seismic body waves?
[ ] A. P-waves are transverse and travel through solids only; S-waves are compressional and travel
through all media.
[ ] B. P-waves are compressional and travel through solids, liquids, and gases; S-waves are transverse
and travel through solids only.
[ ] C. S-waves are compressional and faster than P-waves; P-waves are transverse and cannot travel
through liquids.
[ ] D. Both P- and S-waves are surface waves that cause the most damage and travel only along the
Earth's surface.
CORRECT: B. P-waves are compressional and travel through solids, liquids, and gases; S-waves are
transverse and travel through solids only.
P-waves are compressional (push-pull) and can propagate through solids, liquids, and gases. S-waves are
transverse (shear) and cannot travel through liquids, which is why they are absent in the outer core. The
other options mischaracterize wave types or media.
3. A magnitude 7.0 earthquake occurs at a depth of 15 km along a transform boundary.
Which combination of hazards is most likely to be the primary concern for a nearby
coastal city built on unconsolidated sediments?
[ ] A. Tsunami and volcanic eruption
[ ] B. Liquefaction and ground shaking amplification
[ ] C. Deep-seated landslides and fault creep
[ ] D. Subsidence and permafrost thaw
CORRECT: B. Liquefaction and ground shaking amplification
Unconsolidated sediments amplify ground shaking and are prone to liquefaction during shallow earthquakes.
Transform boundaries do not typically generate tsunamis or volcanic eruptions, and permafrost thaw is
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, unrelated to tectonic setting.
4. A seismograph station records an earthquake with a maximum amplitude of 20 mm on a
Wood-Anderson seismograph at an epicentral distance of 100 km. Using the Richter
magnitude formula M_L = log10(A) + 2.76 log10(D) - 2.48 (where A is in mm and D is in
km), what is the magnitude?
[ ] A. 4.5
[ ] B. 5.0
[ ] C. 5.5
[ ] D. 6.0
CORRECT: C. 5.5
Intensity (MMI) measures the effects at a specific location and depends on distance, local site conditions
(e.g., sediment vs. bedrock), and building construction. Magnitude is an instrument-based measure of energy
release and is not derived from intensity. The other options misstate the relationship between magnitude and
intensity or incorrectly assume uniform intensity.
5. Which tectonic setting is most likely to produce a megathrust earthquake with a
tsunami?
[ ] A. Mid-ocean ridge
[ ] B. Continental transform fault
[ ] C. Oceanic subduction zone
[ ] D. Continental rift valley
CORRECT: C. Oceanic subduction zone
Megathrust earthquakes occur at subduction zones where an oceanic plate is thrust beneath a continental or
oceanic plate, displacing large volumes of water and generating tsunamis. Mid-ocean ridges and transform
faults typically produce smaller, shallower earthquakes, and continental rifts produce normal-fault
earthquakes with limited tsunami potential.
6. A seismogram shows a P-wave arrival at 08:00:00 and an S-wave arrival at 08:00:12.
Using the standard travel-time curve, what is the approximate epicentral distance?
[ ] A. 50 km
[ ] B. 100 km
[ ] C. 150 km
[ ] D. 200 km
CORRECT: B. 100 km
The S-P time is 12 seconds. On a standard travel-time curve, an S-P interval of 12 seconds corresponds to
HIGHP - Page 3 of 18
and Answers | 2026/2027 Updated | 100%
Correct - Arizona State University.
Practice Question Bank & Answer Rationale
THIS PACK CONTAINS
50 exam-style multiple-choice questions. Each question includes the correct answer and a complete rationale
for focused revision.
COVERAGE
This lab exam assesses mastery of earthquake terminology, seismic wave propagation, epicenter location via
triangulation, magnitude and intensity measurement, plate-tectonic controls on seismicity, and societal hazard
and preparedness concepts. Questions require multi-step reasoning, S-P time analysis, and synthesis of
seismological data with tectonic setting.
STUDY GUIDE
Recommended duration: 2 hours 50 minutes. Passing target: 70% (C or better for lab credit).
HIGHP - Page 1 of 18
,1. A seismogram at a station 120 km from the epicenter records a P-wave arrival at
10:12:20.0 UTC and an S-wave arrival at 10:12:36.0 UTC. If the S-wave velocity is 3.5 km/s,
what is the average P-wave velocity over this path?
[ ] A. 5.6 km/s
[ ] B. 6.0 km/s
[ ] C. 7.0 km/s
[ ] D. 8.4 km/s
CORRECT: C. 7.0 km/s
The S-P time difference is 20 seconds. The S-wave travel time is distance/S-velocity = 100 km / 2.5 km/s =
40 s, so the P-wave travel time is 40 s - 20 s = 20 s. Therefore, P-wave velocity = 100 km / 20 s = 5.0 km/s.
Options A, B, and D would yield different S-P times and are inconsistent with the given data.
2. Which statement correctly distinguishes the motion and propagation medium of
seismic body waves?
[ ] A. P-waves are transverse and travel through solids only; S-waves are compressional and travel
through all media.
[ ] B. P-waves are compressional and travel through solids, liquids, and gases; S-waves are transverse
and travel through solids only.
[ ] C. S-waves are compressional and faster than P-waves; P-waves are transverse and cannot travel
through liquids.
[ ] D. Both P- and S-waves are surface waves that cause the most damage and travel only along the
Earth's surface.
CORRECT: B. P-waves are compressional and travel through solids, liquids, and gases; S-waves are
transverse and travel through solids only.
P-waves are compressional (push-pull) and can propagate through solids, liquids, and gases. S-waves are
transverse (shear) and cannot travel through liquids, which is why they are absent in the outer core. The
other options mischaracterize wave types or media.
3. A magnitude 7.0 earthquake occurs at a depth of 15 km along a transform boundary.
Which combination of hazards is most likely to be the primary concern for a nearby
coastal city built on unconsolidated sediments?
[ ] A. Tsunami and volcanic eruption
[ ] B. Liquefaction and ground shaking amplification
[ ] C. Deep-seated landslides and fault creep
[ ] D. Subsidence and permafrost thaw
CORRECT: B. Liquefaction and ground shaking amplification
Unconsolidated sediments amplify ground shaking and are prone to liquefaction during shallow earthquakes.
Transform boundaries do not typically generate tsunamis or volcanic eruptions, and permafrost thaw is
HIGHP - Page 2 of 18
, unrelated to tectonic setting.
4. A seismograph station records an earthquake with a maximum amplitude of 20 mm on a
Wood-Anderson seismograph at an epicentral distance of 100 km. Using the Richter
magnitude formula M_L = log10(A) + 2.76 log10(D) - 2.48 (where A is in mm and D is in
km), what is the magnitude?
[ ] A. 4.5
[ ] B. 5.0
[ ] C. 5.5
[ ] D. 6.0
CORRECT: C. 5.5
Intensity (MMI) measures the effects at a specific location and depends on distance, local site conditions
(e.g., sediment vs. bedrock), and building construction. Magnitude is an instrument-based measure of energy
release and is not derived from intensity. The other options misstate the relationship between magnitude and
intensity or incorrectly assume uniform intensity.
5. Which tectonic setting is most likely to produce a megathrust earthquake with a
tsunami?
[ ] A. Mid-ocean ridge
[ ] B. Continental transform fault
[ ] C. Oceanic subduction zone
[ ] D. Continental rift valley
CORRECT: C. Oceanic subduction zone
Megathrust earthquakes occur at subduction zones where an oceanic plate is thrust beneath a continental or
oceanic plate, displacing large volumes of water and generating tsunamis. Mid-ocean ridges and transform
faults typically produce smaller, shallower earthquakes, and continental rifts produce normal-fault
earthquakes with limited tsunami potential.
6. A seismogram shows a P-wave arrival at 08:00:00 and an S-wave arrival at 08:00:12.
Using the standard travel-time curve, what is the approximate epicentral distance?
[ ] A. 50 km
[ ] B. 100 km
[ ] C. 150 km
[ ] D. 200 km
CORRECT: B. 100 km
The S-P time is 12 seconds. On a standard travel-time curve, an S-P interval of 12 seconds corresponds to
HIGHP - Page 3 of 18
