GeologyLesson 2 of 4 in the course Earthquakes and volcanoes

Seismic Waves: Wave Types, Earth's Modes, and Earthquake Location

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Seismic waves carry energy through Earth and other planetary bodies. Understanding their sources and how they travel helps scientists study earthquakes and infer what lies beneath the surface.

A seismic wave is a mechanical wave of acoustic energy that travels through Earth or another planetary body. Earthquakes are an important source, but seismic waves can also result from volcanic eruptions, magma movement, large landslides, and large human-made explosions that generate low-frequency acoustic energy.

All flashcards

Seismic wave
A mechanical wave that carries energy through Earth or another planetary body.
Seismic-wave velocity
Depends on wave type and on the medium's density and elasticity.
P wave
A fast, compressional body wave that travels through solids, liquids, and gases.
S wave
A transverse shear body wave that travels through solids, but not fluids.
Normal mode
A standing-wave oscillation of Earth produced by interfering seismic waves.

Quiz questions

  1. Which description best characterizes surface waves?Answer: They travel along Earth's surface and are generally slower than body waves.
  2. Which description identifies Love waves?Answer: Horizontally polarized shear waves that occur in layered media.
  3. Interfering Rayleigh waves produce which type of Earth's normal mode?Answer: Spheroidal oscillations.
  4. For a nearby earthquake, a station records a P–S arrival-time difference of 7 seconds. Using the rule of thumb for distances under 200 km, what is the approximate distance?Answer: 56 km.
  5. In earthquake location, what is a residual?Answer: The difference between an observed and a predicted arrival time.

Based on the Wikipedia article Seismic wave, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

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