1. Earthquakes

2. What causes Earthquakes? Earthquakes are sudden movements or vibrations in the earth’s crust. They are caused by faulting and folding activity along converging plate boundaries, as well as with landslides and volcanic activity.

3. Where do they occur? The most and the strongest are located along subduction and transform plate boundaries. Minor earthquakes can occur with volcanic activity or landslides.

4. http://video.nationalgeographic.com /video/environment/environment- natural- disasters/earthquakes/earthquake- 101/http://video.nationalgeographic.com /video/environment/environment- natural- disasters/earthquakes/earthquake- 101/

5. Focus: The actual location in the earth where the earthquake occurs. Epicenter: the point on the surface directly above the earthquake focus.

6. Tectonic creep: rock masses sliding past each other at a fairly regular rate releasing strain energy. At times these rock masses lock up and strain builds up. They snap back into unstrained position. This releases energy outward as a seismic shock producing an earthquake. Example: San Andreas fault in California.

7. How are Earthquakes Measured? Mercali scale: the intensity of the earthquake is measured. This is a measure of the human experience, and the impact of the earthquake. Values are determined by observing the damage done to structures.

8. Richter Scale: The most common scale used to measure Earthquakes. It is based on intensity over a given distance. The largest Earthquakes record have measured just over 9.0 on the Richter scale.

9. Earthquakes over 9.0 on the Richter scale are very rare. Example: –2004 Indian Ocean earthquake of magnitude 9.3 (caused a devastating tsunami) –1960 Chilean earthquake of a magnitude of 9.5.

10. http://www.britannica.com/blogs/20 08/12/the-indian-ocean-earthquake- of-2004-will-history-repeat-itself/http://www.britannica.com/blogs/20 08/12/the-indian-ocean-earthquake- of-2004-will-history-repeat-itself/

11. A megathrust earthquake is an earthquake that can exceed 9.0 on the Richter scale. These generally occur where one plate subducts (slips below) another plate. Most occur in the Pacific or Indian Oceans, and because of the fact that they deform the ocean floor, tsunamis are usually associated with them.

12. Secondary Effects of Earthquakes There can be several secondary effects of earthquakes: –Tsunamis –fire and gas lines damaged or broken –flooding, –landslides, –famine / disease, –land altered (ex: shoreline raised 30 feet in Alaska, 1964).

13. Earthquakes can cause a lot of damage and deaths in a matter of seconds. Examples: –China 1976: whole city destroyed, deaths around 600,000 –China 1556: 830,000 people killed

14. Questions Explain how Earthquakes are measured using Seismometers. Read the “Tragedy in Turkey” on page 56/57 in your text book and answer questions 1, 2, and 3. Answer question 8 and 13 on page 61.