1. Plate Tectonics and Earthquakes

2. Plate Tectonics The Earth’s outer most layer called the lithosphere is divided up into large pieces called Tectonic Plates These plates glide across the semi-solid asthenosphere layer at a rate of about 2 cm a year. Alfred Wegener came up with the ideas of Pangea and Continental Drift Tectonic plates separate from one another, collide with one another and slip past one another. This motion is responsible for mountain building on coasts and land expansion in the central regions of continents called Rifting. Enormous amounts of energy is built up near plate boundaries and when this energy is released Earthquakes occur.

3. Plate Tectonics and Earthquakes The space between tectonic plates is called a fault, a break in the Earth’s crust along which the crustal blocks can move relative to one another. When these blocks move against one another the released energy causes vibrations of the surrounding land masses called an Earthquake. This video show what happens when the energy is released in a populated area. Notice what the people in the office building do. http://www.classzone.com/books/earth_science/terc/cont ent/visualizations/es1005/es1005page01.cfm?chapter_no=vi sualization http://www.classzone.com/books/earth_science/terc/cont ent/visualizations/es1005/es1005page01.cfm?chapter_no=vi sualization

4. Earthquake Strength History –A whole lot of shaking going on Seismologist-Earthquake specialists A scale to measure the Intensity of earthquake shaking and the damage this caused was established in 1902 by a geologist named Guiseppe Mercalli called the Modified Mercalli Intensity Scale, this scale is still used today. Range I thru XII. The Richter Scale developed by Charles Richter in 1935 uses data recorded from seismic wave activity to estimate the size or Magnitue of an earthquake. Range 0 thru 7. For every increase of one on the Reichter scale there is 32- fold increase in energy released.

5. Where do Earthquakes Occur Most Earthquakes occur at or near tectonic plate boundaries. In the United States earthquakes are frequently occur along the San Andreas Fault along the coast of California. Here is where the North American Plate on the right slips past the Pacific Plate on the left.

6. Earthquake Warning Systems Its hard to know when an Earthquake is going to occur but the use of technology in the form of Seismographs can alert people to the possibility of the occurrence of an Earthquake. Seismograms measure the movement of the earth. These movements are recorded on a rolling graph paper tube. The greater the intensity of ground shaking the taller the markings on the paper. Biology Connection Animals have also been used to predict impending Earthquake activity; birds may leave their habitats and animals zoo animals may refuse to enter their shelters.

7. Building for Earthquakes Earthquakes are so frequent in Japan that the buildings are outfitted with special gliding foundations that move with ground movement to prevent destruction to tall buildings

8. Earthquakes in Illinois Research the occurrence of earthquakes in Illinois Answer the following questions 1. Could an earthquake occur in your backyard? If not where might one happen in our state? 2. When did the last earthquake take place in Illinois? 3. How far was this earthquake from Chicago and was it detected by seismogram reading. 4. What was the strength of this earthquake on the Richter scale? Visit the U.S. Geological Survey to get information http://earthquake.usgs.gov