Earthquakes

What is an Earthquake?? An earthquake is caused by the release of stored energy in Earth’s outer layer. This causes sudden shift of rocks. An earthquake generates movements and vibrations that travel through the earth

Defining Earthquakes Shaking and trembling of the earth’s crust. The waves travel in all directions More than 1,000,000 occur a year or one every 30 seconds Faulting is the most common cause Earthquakes continue until all the energy is used up TSUNAMIS- earthquake on the ocean floor: causing waves to become greater than 20 meters high

Although the ground we walk on seems solid, the earth is actually made up of huge pieces of flat rock called tectonic plates. These move very slowly, and where they meet is called a fault. When the plates rub together, the movement forces waves of energy to come to the earth's surface. This causes tremors and shakes - and this is what causes earthquakes.

Seismic Waves FAULT- the break FOCUS-place where movement begins As rocks move, energy is released by vibrations or seismic waves The three main types of seismic waves are: P waves, S waves, and L waves

P Waves Primary waves Fastest seismic waves First to arrive at a distant point Can travel through solids, liquids, and gases They are push-pull waves

S Waves Secondary waves Slower than P waves and arrive later at a distant point Can travel through solids, but NOT through liquids and gases Move in up-down motion Link Link 2

L Waves Surface waves Slowest moving seismic waves Travel on top of Earth’s surface Cause most of damage to Earth, because they move the ground up and down, side by side Link

John Milne- 1893 Seismograph-measures and detects seismic waves Seismogram- Paper record of waves Seismologist- scientist who study earthquakes Richter Scale- a scale that allows scientists to determine earthquake strength based on many readings 1-10 levels at which an earthquake is measured on amount of damage caused; Above a 6 is very destructive seismograph

The “EARTHQUAKE GAME” – 1988                                                        Eddie Fuller catches Tommy Hodson’s fourth-down pass in the end zone to tie the score 6-6 with Auburn in 1988 with 1:47 remaining in the game. The crowd’s reaction registered on the seismograph in LSU’s Howe-Russell Geoscience Complex. During the 1988 Auburn-LSU football game LSU scored a late and winning touchdown. The crowd cheered so loudly that the “earthquake game” made local history because the ground motion appeared on the LSU seismograph. http://www.classzone.com/books/earth_science/terc/content/visualizations/es1009/es1009page01.cfm