Vibrations caused by earth movements at plate boundaries and at major fault lines (cracks in the earth's surface)
Earthquakes
They can occur at all four major plate boundaries but the most severe earthquakes are normally found at conservative and destructive plate boundaries
Destructive plate boundary
Plates move towards each other and one is pushed under the other
Conservative plate boundary
Plates slide past each other
Richter Scale
Measures the magnitude of a tremor (how powerful it is) using a seismograph. It is a logarithmic scale where each whole number increase represents a 10-fold increase in magnitude.
The largest earthquake ever recorded was in 1960 in Chile, measuring 9.5 on the Richter Scale
The Japanese earthquake in Kobe (1995) measured 7.2 on the Richter Scale
It was 10 times more powerful than the Greek earthquake (1995) which measured 6.2
Mercalli Scale
Measures the amount of damage caused by an earthquake based on observations, on a scale from I to XII
Epicentre
The point on the earth's surface directly above the focus (where the rock movement occurs)
Focus
The point at which the rock moves, where the seismic waves start
Predict
Water levels can rise, foreshocks can be detected, animals can act strangely before the earthquake
Plan and protect
Have an emergency kit, design earthquake-proof buildings, have building regulations in earthquake zones
Factors affecting earthquake damage include size of earthquake, time of day, emergency services, building design, education, and physical landscape
Tsunamis are tidal waves triggered by underwater earthquakes, which can travel at 400-600 miles per hour
The 2004 SE Asian tsunami was triggered by a 9.0 magnitude earthquake off Sumatra, and killed around 290,000 people
