EARTH

• Body waves


  One of the two main types of waves, named because they move through the body of an object
• Elastic waves


  One of the two main types of waves
• Epicenter


  The part of the earth's surface directly above the focus of an earthquake
• Hypocenter


  The focus of an earthquake, the point where the earthquake originates
• Seismology


  The study of earthquakes and seismic waves that move through and around the earth
• Seismograph


  An instrument used to record the motion of the ground during an earthquake
• Seismogram


  A record produced by a seismograph, used to determine the location and magnitude of an earthquake
• Triangulation method


  Formula: d = Td x 8 km/s, where d = distance (km) and Td = time difference (s) in the P-wave and S-wave arrival time
• Pelagic waves are one of the two main types of waves