GeologyLesson 1 of 2 in the course Earthquakes and volcanoes

Earthquakes: Faults, Measurement, Hazards, and Risk

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

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Summary

Earthquakes range from barely noticeable tremors to destructive events that can affect entire regions. This lesson introduces what earthquakes are, how they are described, and why their impacts vary.

An earthquake is shaking of Earth's surface caused by a sudden release of energy in the lithosphere. This release creates seismic waves that travel through Earth and along its surface. The terms quake, tremor, and temblor are also used for earthquakes, although tremor can sometimes refer to seismic rumbling that is not an earthquake.

All flashcards

Seismicity
The average rate of seismic energy released per unit volume at a location.
Hypocenter
The point within Earth where an earthquake's rupture begins.
Epicenter
The point at Earth's surface directly above the hypocenter.
Site amplification
Increased shaking caused when local ground conditions amplify seismic waves.
Seismic retrofitting
Strengthening an existing structure to better resist earthquake forces.

Quiz questions

  1. What term describes the gradual buildup of strain in locked rock followed by sudden fault rupture?Answer: Elastic-rebound theory
  2. What does earthquake magnitude describe?Answer: The size of an earthquake at its source
  3. Which fault type moves mainly by horizontal motion of blocks past one another?Answer: Strike-slip fault
  4. What distinguishes an earthquake swarm from a typical mainshock-aftershock sequence?Answer: No single event clearly stands out as the mainshock.
  5. What does an earthquake early-warning system do?Answer: Detects an earthquake in progress and alerts people before strong shaking arrives.

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

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