• Earthquakes happen all the time, and can be barely noticeable or terribly devastating. What causes them? What can we do to be prepared?

    1. What causes earthquakes?

      Masses of rock shift below the Earth's surface, causing changes in pressure and seismic waves.

    2. Approximately how many earthquakes occur each year that people can feel? How many of these cause property damage?

      Approximately 100,000 earthquakes are felt by people each year, with about 1,000 causing property damage.

    3. How many times more energy does a magnitude 5 earthquake release than an earthquake with a magnitude of 4?

      A magnitude 5 earthquake releases thirty times more energy than a magnitude 4 earthquake.

    4. What are engineers focusing on to keep people safe from earthquakes in the future?

      They are focusing on ways to create safer buildings, highways, and bridges.

    • About 80% of the planet's earthquakes occur along the rim of the Pacific Ocean due to the fault lines there.
    • According to the video, scientists use the Richter Scale to rate earthquakes based on the strength and duration of their seismic waves. Today, most scientists use the moment magnitude scale.
    • Earthquakes often cause other hazards, such as mud slides, fires, floods and tsunamis.
  • Term Part of Speech Definition Encyclopedic Entry
    earthquake Noun

    the sudden shaking of Earth's crust caused by the release of energy along fault lines or from volcanic activity.

    fault line Noun

    fracture in a rock caused by tectonic activity pulling one side of the rock in a different direction.

    Richter scale Noun

    ordered series of numbers (1-10) used to indicate the amount of energy released during an earthquake. The Richter scale is now outdated. Scientists now use the moment-magnitude scale.

    seismic shock wave Noun

    vibration that travels from the focus of an earthquake in all directions.

    seismograph Noun

    instrument that detects and records vibrations caused by seismic shock waves.

    tectonic plate Noun

    massive slab of solid rock made up of Earth's lithosphere (crust and upper mantle). Also called lithospheric plate.