Earth Science Mr. Barry

 Focus : the point where an earthquake originates  Epicenter : the point on Earth’s surface directly above the focus  Fault : location along which an earthquake originates

 Seismic Waves : vibrations of the ground during an earthquake  Primary Waves (P-waves): squeeze and pull rocks in the same direction along the direction the wave is traveling

 Secondary Waves (S-Wave): cause rocks to move at right angles in relation to the direction of the wave  Surface Waves : move in two directions (up and down), what it actually felt on the surface

 Seismometer : device used to measure the strength of earthquakes. A hanging device records vibrations  Seismogram : the record produced by a seismometer

 Magnitude : the amount of energy released by an earthquake  Richter Scale : earthquake rating based on the size of the seismic waves released by the earthquake

 Structures: buildings fall as ground shakes  Fires: disturbed soil destroys gas and power lines, leading to fires  Land/Soil: landslides are a common result of earthquakes

 Tsunami : a large ocean wave generated by vertical motions of the seafloor during an earthquake

 Earthquake prediction is based largely on probability. Factors used for these predictions are:  Earthquake history: many hot spots have earthquake recurrences  Seismic Gaps: active faults that have not experienced an earthquake recently  Strain accumulation : the build up of strain in one location