GED Science TestEarth and Space ScienceMedium
A geophysicist is studying the Earth's interior and observes that seismic P-waves change speed and direction as they pass through a particular layer. S-waves, however, are completely absorbed and do not pass through this layer. Which layer of Earth's interior is the geophysicist observing?
- AOuter Core
- BInner Core
- CCrust
- DMantle
Show answer & explanationAnswer & explanation
Correct answer: A. Outer Core
The Earth's outer core is composed of liquid iron and nickel. P-waves can travel through liquids but slow down and refract. S-waves, which are shear waves, cannot travel through liquids and are therefore absorbed, creating an S-wave shadow zone. This behavior is characteristic of the outer core.
Why the other options are wrong
- B. The inner core is solid; both P and S waves travel through it at increased speeds.
- C. The crust is solid; both P and S waves travel through it.
- D. The mantle is mostly solid; both P and S waves travel through it, though speeds change.
Outer Core Characteristics
A liquid layer of Earth's interior, primarily composed of iron and nickel, where S-waves are absorbed and P-waves refract and slow down.
- Located between the mantle and the inner core.
- Responsible for generating Earth's magnetic field through convection.
- Temperature ranges from approximately 4,400°C to 6,100°C.
Memory trick: P-waves Pass, S-waves Stop: Outer Core's Liquid Plot.