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Zorluk: ZorInternal and External Structure of the Earth

Geophysical observations indicate that shear (SS) seismic waves cannot travel through the outer core, while the partially molten asthenosphere enables mechanical movement of the rigid outer shell above it. Which of the following statements accurately explains the physical properties and dynamic interaction of these internal and external structural layers of the Earth?

  1. The asthenosphere exhibits ductile plastic flow that supports lithospheric plate motion, while the liquid state of the outer core absorbs shear stress and blocks SS-wave transmission.Cevap
  2. B
    The sial layer continuously converts into metamorphic marble beneath the oceans to produce mantle convection currents within the solid inner core.
  3. C
    The barysphere undergoes in-situ chemical weathering to generate downslope mass wasting movements that form the Earth's atmosphere.
  4. D
    The oceanic crust consists of light granitic rocks that undergo sedimentary deposition inside the mesosphere to stop PP-wave transmission.

Cevap

The asthenosphere exhibits ductile plastic flow that supports lithospheric plate motion, while the liquid state of the outer core absorbs shear stress and blocks SS-wave transmission.
The asthenosphere's partially molten, ductile nature allows it to deform plastically, providing the lubricated substrate over which rigid lithospheric plates move. Furthermore, shear (SS) waves cannot propagate through liquid media because liquids lack shear strength, which accounts for the SS-wave shadow zone produced by the liquid metallic outer core.

Adım Adım Çözüm

1
Analyze the physical state and function of the asthenosphere and lithosphere.
The asthenosphere, situated in the upper mantle, exists in a semi-fluid or ductile state. This plasticity allows the cooler, rigid lithospheric plates floating above it to undergo movement.
Internal heat differential drives plastic flow in the asthenosphere, enabling plate tectonics.
2
Evaluate seismic wave behavior through liquid internal layers.
Transverse (SS) waves require shear strength to propagate through a medium. Because liquids have zero shear strength, SS-waves are completely blocked by the liquid outer core.
The boundary between the solid mantle and liquid outer core (Gutenberg Discontinuity) causes an SS-wave shadow zone.

Anahtar Kavram

Physical state, seismic wave propagation, and dynamic interaction of Earth's internal layers (asthenosphere, outer core) and external lithosphere.
Tahmini Süre:1m 30s
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Internal and External Structure of the Earth

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