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Earthquakes

Learn about earthquakes, their causes, and the effects they have on the environment. Discover how to stay safe during an earthquake and understand the measurement scales used to quantify their magnitude and intensity.

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Earthquakes

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  1. Earthquakes

  2. What is an Earthquake? • A sudden motion or trembling of the Earth caused by the abrupt release of slowly accumulated elastic energy in rocks

  3. Effects of Earthquakes • Ground Shaking • Fault Rupture and Uplift • Liquefaction • Dam Breaks • Landslides • Tsunami • Aftershocks • Fire

  4. Ground Shaking

  5. Fault Rupture

  6. Liquefaction • Loose sand and mud turns into quicksand as groundwater rises • Heavy objects sink in and light objects pop out

  7. Liquefaction

  8. Dam Breaks

  9. Landslides

  10. Tsunamis How high was the largest tsunami? • The largest tsunami recorded measured 210 feet, about 18 stories above sea level, when it reached Siberia's Kamchatka Peninsula in 1737.

  11. Aftershocks • Major earthquakes are followed by a larger number of aftershocks, decreasing in frequency with time.

  12. Fires

  13. Earthquake Zones in the U.S.A. • College of Alameda Physical GeographyRita Haberlin, Instructor

  14. The Great New Madrid Earthquake

  15. Go to this website and find your area and add the maps: http://earthquakes.usgs.gov/

  16. Again copy and paste your location

  17. How are Earthquakes Measured? • Richter scale - measures the magnitude of energy released at the focus • Modified Mercalli scale measures the intensity of an earthquake according to damage observed

  18. Modified Mercalli Intensity

  19. I. Not felt except by a very few under especially favorable conditions. • II. Felt only by a few persons at rest, especially on upper floors of buildings. • III. Felt quite noticeably by persons indoors, especially on upper floors of buildings. Many people do not recognize it as an earthquake. Standing motor cars may rock slightly. Vibrations similar to the passing of a truck. Duration estimated. • IV. Felt indoors by many, outdoors by few during the day. At night, some awakened. Dishes, windows, doors disturbed; walls make cracking sound. Sensation like heavy truck striking building. Standing motor cars rocked noticeably. • V. Felt by nearly everyone; many awakened. Some dishes, windows broken. Unstable objects overturned. Pendulum clocks may stop.

  20. VI. Felt by all, many frightened. Some heavy furniture moved; a few instances of fallen plaster. Damage slight. • VII. Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken. • VIII. Damage slight in specially designed structures; considerable damage in ordinary substantial buildings with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture overturned. • IX. Damage considerable in specially designed structures; well-designed frame structures thrown out of plumb. Damage great in substantial buildings, with partial collapse. Buildings shifted off foundations.

  21. X. Some well-built wooden structures destroyed; most masonry and frame structures destroyed with foundations. Rails bent. • XI. Few, if any (masonry) structures remain standing. Bridges destroyed. Rails bent greatly. • XII. Damage total. Lines of sight and level are distorted. Objects thrown into the air.

  22. Richter Magnitude

  23. Richter Magnitude • Less than 3.5 Generally not felt, but recorded. • 3.5-5.4 Often felt, but rarely causes damage. • Under 6.0 At most slight damage to well-designed buildings. Can cause major damage to poorly constructed buildings over small regions. • 6.1-6.9 Can be destructive in areas up to about 100 kilometers across where people live. • 7.0-7.9 Major earthquake. Can cause serious damage over larger areas. • 8 or greater Great earthquake. Can cause serious damage in areas several hundred kilometers across.

  24. How Often Do Earthquakes Occur?

  25. What to do during an Earthquake • If you are in bed: • Remain in bed until the shaking stops • Hold on • Protect your head with pillow

  26. What to do during an Earthquake • If you are driving: • Slow down • Drive to a clear area and stop • Remain in the car until the shaking stops

  27. What to do during an Earthquake • If you are outdoors: • Find a clear spot away from tree, power lines, and buildings • Drop to the ground • If you are near a tall building: • Duck into a doorway to avoid debris from above

  28. References • The Great New Madrid Earthquake from the virtual times http://hsv.com/genlintr/newmadrd • College of Alameda Physical Geography Rita Haberlin, Instructor • www.usgs.gov • Some images came from google image search

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