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Earthquakes

Learn all about earthquakes - the vibrations within the Earth caused by the release of energy. Discover the different forces that create earthquakes, including tension, compression, and shear forces. Explore the causes of earthquakes, such as movement along faults and volcanic eruptions. Understand the types of seismic waves and how they are measured using seismographs and scales like the Richter Scale. Also, explore the potential dangers of earthquakes, including falling objects, fires, tsunamis, and landslides.

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Earthquakes

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  1. Earthquakes

  2. What is an Earthquake? • Vibrations (seismic waves) within Earth produced by the rapid release of energy • Crust is in constant motion • Stores elasticenergy • When forces exceed the limits and strength of the rocks, they will break and/or move producing vibrations that travel outward in ALL directions

  3. Earthquakes • The actual place underground where the rocks break producing vibrations is called the focus • The place on the surface directly above the focus is called the epicenter

  4. What types of forces are created? Tension Force: • stretching or pulling force • Makes a normal fault

  5. Normal Fault http://www.geo.uib.no/jordskjelv/index.php?topic=earthquakes&lang=en

  6. What types of forces are created? Compression Force: • force pushing something together • Makes a reverse fault

  7. Reverse Fault http://www.geo.uib.no/jordskjelv/index.php?topic=earthquakes&lang=en

  8. What types of forces are created? Shear Force: • a system of forces that operates against a body from different sides • Makes a strike-slip fault

  9. Strike-Slip Fault http://www.geo.uib.no/jordskjelv/index.php?topic=earthquakes&lang=en

  10. What causes Earthquakes? • Movement along faults: energy exceeds the friction holding the sides together and is suddenly released. • Movement of magma in the asthenosphere • Volcanic eruptions

  11. Seismic Waves

  12. 3 Types of seismic Waves • P waves (primary waves) Compressional wave • Particles move back and forth in the same direction as the wave • Travels the fastest • Can pass through solids and liquids (gases also) • Does not cause damage

  13. Types of Waves • S wave (secondary wave, shear wave) • Particles move at right angles to the direction of the wave • Travels slower than P waves • Can pass through solids only • Does not cause damage

  14. Types of Waves • Surface wave • Particles move in elliptical orbit • Originates on the surface after the P and S waves go straight up from the focus and reach the surface • The L wave causes the damage and will be the strongest at the epicenter • Travels the slowest

  15. How do we Measure Earthquakes? Earthquake are recorded by a seismograph

  16. How do we Measure Earthquakes? • Intensity – a measure of the effects on an earthquake at a particular location • Magnitude: a measure of the strength or amount of energy released during an earthquake

  17. How do we Measure Earthquakes? • Richter Scale: Measures the amplitude of earthquake waves on seismograms • Scale from 1-10 • Each number is 10 times the amplitude of the number below

  18. Earthquake Dangers • Most injuries and deaths are caused by falling objectsand most property damage results from fires that start • Tsunami: seismic sea wave sometimes generated when an earthquake originates on the ocean floor

  19. Tsunami—December 2004 http://www.bedford.k12.ny.us:16080/flhs/science/images/tsunami2004/

  20. Earthquake Dangers • Landslides

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