earthquakes

• Earthquakes are the sudden movement of the Earth's crust which causes gentle to violent tremors on the Earth's surface
• Seismic activity (earthquakes) occur when plates slide past each other, causing huge pressure to build up and release suddenly
• Features of an earthquake:

  • Focus/hypocenter: the source or origin of an earthquake where the first and strongest seismic waves are felt
• Seismic waves are vibrations/shock waves given off from an earthquake. There are two types:

  • Primary (P) waves: the first waves felt which travel through solids, liquids, and gases in a back and forth (lateral) motion
  • Secondary (S) waves: the second waves felt which travel through solids only in an up and down motion
• Magnitude describes the strength of an earthquake and is measured on a moment magnitude scale. The Richter scale is also used to measure magnitude