ESS 101 A LAB 2: ADVANCED PLATE
TECTONICS AND SEISMOLOGY
QUESTIONS AND ANSWERS 2026/2027
UPDATE || 100% GUARANTEED PASS
1. Which geophysical mechanism is primarily responsible for the generation of the Earth’s
magnetic field?
A. Tidal forces from the Moon acting on the crust
B. Permanent magnetism within the solid inner core
C. Piezoelectric effects within quartz-rich lithospheric rocks
D. Convection of molten iron in the outer core
Answer: D
Conceptual Explanation: The geodynamo effect is caused by the convection of conducting
liquid iron in the outer core combined with the Earth’s rotation.
2. In the context of the Wilson Cycle, which stage is characterized by the initial thinning of the
continental lithosphere and the formation of a rift valley?
A. Embryonic Stage
B. Terminal Stage
C. Suturing Stage
,D. Mature Stage
Answer: A
Conceptual Explanation: The Embryonic Stage involves continental rifting due to
upwelling mantle plumes, creating rift valleys like the East African Rift.
3. What is the significance of the 660-km discontinuity in the Earth’s mantle?
A. It marks the transition from the lithosphere to the asthenosphere
B. It is the boundary where S-waves cease to propagate
C. It represents the phase change of ringwoodite to bridgmanite and ferropericlase
D. It is the depth at which partial melting first occurs at mid-ocean ridges
Answer: C
Conceptual Explanation: The 660-km discontinuity is a major mineralogical phase
transition that increases density and seismic velocity in the lower mantle.
4. Which of the following best describes the ‘Slab Pull’ force in plate tectonics?
A. The negative buoyancy of a subducting cold, dense lithospheric plate
B. The suction force created by the descending mantle at a subduction zone
C. The gravitational sliding of a plate away from a mid-ocean ridge
D. The frictional drag of the asthenosphere on the base of the lithosphere
Answer: A
, Conceptual Explanation: Slab pull is considered the dominant force driving plate motion,
resulting from the density difference between the cold subducting slab and the warmer
surrounding mantle.
5. Which type of seismic wave is characterized by a retrograde elliptical particle motion?
A. Rayleigh waves
B. Love waves
C. P-waves
D. S-waves
Answer: A
Conceptual Explanation: Rayleigh waves are surface waves that cause the ground to
shake in an elliptical motion, similar to ocean waves.
6. In a Wadati-Benioff zone, what does the distribution of earthquake foci indicate?
A. The presence of a transform fault connecting two ridges
B. The width of the rift valley at a divergent boundary
C. The angle and depth of a subducting oceanic plate
D. The thickness of the continental crust in a collision zone
Answer: C
Conceptual Explanation: Wadati-Benioff zones represent the seismic activity within a
subducting slab, showing the path it takes into the mantle.
TECTONICS AND SEISMOLOGY
QUESTIONS AND ANSWERS 2026/2027
UPDATE || 100% GUARANTEED PASS
1. Which geophysical mechanism is primarily responsible for the generation of the Earth’s
magnetic field?
A. Tidal forces from the Moon acting on the crust
B. Permanent magnetism within the solid inner core
C. Piezoelectric effects within quartz-rich lithospheric rocks
D. Convection of molten iron in the outer core
Answer: D
Conceptual Explanation: The geodynamo effect is caused by the convection of conducting
liquid iron in the outer core combined with the Earth’s rotation.
2. In the context of the Wilson Cycle, which stage is characterized by the initial thinning of the
continental lithosphere and the formation of a rift valley?
A. Embryonic Stage
B. Terminal Stage
C. Suturing Stage
,D. Mature Stage
Answer: A
Conceptual Explanation: The Embryonic Stage involves continental rifting due to
upwelling mantle plumes, creating rift valleys like the East African Rift.
3. What is the significance of the 660-km discontinuity in the Earth’s mantle?
A. It marks the transition from the lithosphere to the asthenosphere
B. It is the boundary where S-waves cease to propagate
C. It represents the phase change of ringwoodite to bridgmanite and ferropericlase
D. It is the depth at which partial melting first occurs at mid-ocean ridges
Answer: C
Conceptual Explanation: The 660-km discontinuity is a major mineralogical phase
transition that increases density and seismic velocity in the lower mantle.
4. Which of the following best describes the ‘Slab Pull’ force in plate tectonics?
A. The negative buoyancy of a subducting cold, dense lithospheric plate
B. The suction force created by the descending mantle at a subduction zone
C. The gravitational sliding of a plate away from a mid-ocean ridge
D. The frictional drag of the asthenosphere on the base of the lithosphere
Answer: A
, Conceptual Explanation: Slab pull is considered the dominant force driving plate motion,
resulting from the density difference between the cold subducting slab and the warmer
surrounding mantle.
5. Which type of seismic wave is characterized by a retrograde elliptical particle motion?
A. Rayleigh waves
B. Love waves
C. P-waves
D. S-waves
Answer: A
Conceptual Explanation: Rayleigh waves are surface waves that cause the ground to
shake in an elliptical motion, similar to ocean waves.
6. In a Wadati-Benioff zone, what does the distribution of earthquake foci indicate?
A. The presence of a transform fault connecting two ridges
B. The width of the rift valley at a divergent boundary
C. The angle and depth of a subducting oceanic plate
D. The thickness of the continental crust in a collision zone
Answer: C
Conceptual Explanation: Wadati-Benioff zones represent the seismic activity within a
subducting slab, showing the path it takes into the mantle.
