EARTHQUAKES! Jody Pearl, Kasie Drobnick, Ellen Cochran
An earthquake is… • A phenomenon that results from and is powered by the sudden release of stored energy in the crust that propagates seismic waves.
Why do earthquakes happen? • The earth's crust (the outer layer of the planet) is made up of several pieces, called plates. The plates under the oceans are called oceanic plates and the rest are continental plates. • The plates are moved around by the motion of a deeper part of the earth (the mantle) that lies underneath the crust. • These plates are always bumping into each other, pulling away from each other, or past each other. The plates usually move at about the same speed that your fingernails grow. Earthquakes usually occur where two plates are running into each other or sliding past each other.
Earthquakes occur all the time all over the world, both along plate edges and along faults. • Most earthquakes occur along the edge of the oceanic and continental plates. • http://www.classzone.com/books/earth_science/terc/content/investigations/es1001/es1001page07.cfm Where do most earthquakes happen?
How are earthquakes measured? • Seismology is the study of earthquakes and seismic waves that move through and around the earth. • A seismologist is a scientist who studies earthquakes and seismic waves. • Seismic waves are the waves of energy caused by the sudden breaking of rock within the earth or an explosion. They are the energy that travels through the earth and is recorded on seismographs.
Earthquake Detectors! • Work in teams of 3 to build a replica of an earthquake detector. Use a ruler and scissors to cut 4-inch (10 cm) slits in the bottom edges of the two long sides of the box. • Cut paper into strips slightly smaller than 4 inches (10 cm) wide. Attach pieces together with clear adhesive tape to form a long strip. Insert the strip of paper into the slits so the ends of the strip extend out of the slits. • Attach two rubber bands around the box so the bands are stretched wide to the sides of the other two slits. Place a fine tip marker between the two rubber bands. Cut two pieces of yarn with scissors and tie the marker into place between the rubber bands so the tip lightly rests on the strip of paper in the box. • Work together with one partner jiggling the box and the other pulling the paper through to get a continuous reading of the magnitude of the simulated earthquake.