S-waves

Definition

S-waves, or secondary waves, are a type of seismic wave that move through the Earth during an earthquake. They are shear waves that only travel through solid materials, making them slower than P-waves and responsible for much of the damage associated with earthquakes due to their side-to-side motion.

5 Must Know Facts For Your Next Test

1. S-waves travel at about 60% the speed of P-waves, arriving after the initial shaking of an earthquake.
2. These waves can only propagate through solid rock, which means they do not travel through molten rock or fluids, such as magma or water.
3. The movement of S-waves is perpendicular to the direction of wave propagation, which contributes to their shear force and the potential for structural damage.
4. S-waves provide critical information about the Earth's internal structure because their behavior changes based on the materials they pass through.
5. The inability of S-waves to travel through liquids is used by geologists to infer the presence of liquid outer core beneath Earth's solid mantle.

Review Questions

• How do S-waves differ from P-waves in terms of speed and material they can travel through?
  • S-waves travel slower than P-waves, typically at about 60% of their speed. While P-waves can move through solids, liquids, and gases, S-waves can only propagate through solid materials. This difference is crucial in understanding earthquake dynamics since P-waves provide the first indication of seismic activity while S-waves follow and often cause more intense shaking.
• Discuss the role of S-waves in assessing earthquake hazards and why they are significant in understanding potential damage.
  • S-waves play a vital role in assessing earthquake hazards due to their shear motion, which causes more destruction compared to P-waves. Understanding how S-waves behave allows scientists to evaluate building vulnerabilities and predict areas at higher risk during seismic events. Since these waves arrive after P-waves, they also help in determining the location and magnitude of an earthquake based on seismographic data.
• Evaluate how the characteristics of S-waves contribute to our knowledge of Earth's internal structure and what implications this has for plate tectonics.
  • The characteristics of S-waves provide critical insights into Earth's internal structure because their inability to travel through liquid informs scientists about the composition and state of materials beneath the surface. The fact that S-waves are absorbed by liquid layers indicates the presence of a molten outer core. This understanding is essential for interpreting plate tectonics as it helps explain how different materials interact at boundaries, influencing tectonic activity such as earthquakes.

Related terms

P-waves: Primary waves are the fastest seismic waves and can travel through solids, liquids, and gases. They compress and expand materials in the direction they move.

Seismograph: An instrument that detects and records the motion of seismic waves, allowing scientists to analyze earthquakes and their effects.

Transform Boundary: A tectonic plate boundary where two plates slide past each other, often generating earthquakes due to friction and stress accumulation.