Earthquakes: Basic Features

• Sudden release of stored elastic energy
• Focus vs. epicenter
• Location of world's earthquakes
• Earthquake hazards

Seismic Waves

• P waves (compressional): about 7 km/sec
  • Longitudinal vibration
• S waves (shear): about 4 km/sec
  • Vibration perpendicular to path
• Surface waves: about 2.5 km/sec
  • Deformation of free surface

Measuring Earthquakes

• Seismographs and seismograms
• Richter scale = amplitude _ energy
• Locating the epicenter

Seismic Hazards

• Building collapse
• Ground shift
• Landslides
• Liquifaction
• Tsunamis
• Fire