Which major internal boundary of the Earth separates the mantle from the outer core and is characterized by a sudden drop in seismic wave velocities?
Show answer & explanation
Correct answer: C
Explanation
Solution: The correct answer is Gutenberg Discontinuity.
Explanation:
☛ The Gutenberg Discontinuity separates the Earth's lower mantle from the outer core.
☛ It is located at a depth of approximately 2,900 km beneath the Earth's surface.
☛ At this boundary, primary seismic waves (P-waves) slow down drastically, and secondary seismic waves (S-waves) completely disappear because the outer core is in a liquid state.
☛ It is named after the renowned seismologist Beno Gutenberg, who discovered it in 1913.
Extra Exam-Relevant Facts:
☛ Conrad Discontinuity: Separates the upper crust from the lower crust.
☛ Mohorovicic (Moho) Discontinuity: Separates the crust from the mantle at an average depth of about 35 km.
☛ Repetti Discontinuity: Separates the upper mantle from the lower mantle.
☛ Lehmann Discontinuity: Separates the liquid outer core from the solid inner core at a depth of about 5,150 km.
Important One-Liners for Upcoming Exams:
☛ Which layer of Earth's interior is predominantly composed of nickel and iron (NIFE)? → Core (Barysphere)
☛ Which seismic waves cannot travel through liquids? → S-waves (Secondary waves)
☛ What is the innermost solid layer of the Earth called? → Inner Core
☛ The boundary between the Earth's crust and mantle was discovered by which scientist? → Andrija Mohorovičić
☛ What is the semi-molten upper part of the mantle called? → Asthenosphere