Meaning: a shaking or shock wave that moves through the ground.

Fast Facts:

  • the energy of an earthquake is measured by the Richter scale (from 0 to 10)
  • the effects of an earthquake are measured by the Mercalli scale (from i to xii)
  • they are caused by a sudden movement in the Earth's crust
  • most occur around the Pacific rim
  • a seismograph records the waves produced by earthquakes
  • cities built in earthquake zones have strict rules for building new constructions
  • there are more than 600,000 tremors each year
2 I to II *usually detected only by instruments
3 III *felt indoors, vibration like passing truck
4 IV to V *felt by most people, dishes and windows may fall and break, plaster cracks
5 VI to VII *felt by all, people frightened, slight damage to well-built buildings with considerable damage to all else
6 VII to VIII *great damage to poorly built structures with damage to walls and chimneys in other buildings
7 IX to X *major quake, damage to most buildings, large cracks in ground
8 to 10 X to XII *major destruction to buildings, bridges and underground pipes, landslides and earth slumps