Tectonic Plates

•Tectonic plates are locked together by friction

•Pressure builds up due to movement in the mantle (convection currents)

•Rock breaks along a weak point (fault lines)

•Pressure has built up to such an extent that tectonic plates suddenly move

•The stored energy is released in seismic waves

•The earth’s surface shakes; i.e. EARTHQUAKE

•Happens in areas where there is tectonic activity (normally on tectonic plate boundaries)

•Place beneath the surface where the pressure is released is called the FOCUS of the earthquake

•The EPICENTRE of a quake is on the surface directly above the focus

•Seismic waves are caused and spread out from the focus, getting weaker the further from the focus they are

•Quakes with a focus near the surface are normally more devastating

•Power of a quake is measured using a Seismometer; detects vibration caused by a quake. Plots vibration on a seismograph •Strength, or magnitude, of quake is measured using the Richter Scale; numbered 0-10 •Quakes that measure one/two are common and can happen everyday in some places (San Francisco). So small people don’t feel them, only picked up by a seismometer •Quakes measuring seven/eight can be devastating. Quake in China’s south-western Sichuan province (May 2008) measured 7.8 on the scale. These quakes can cause major loss of life and cost million, even billions of dollars in damage

Social:

• People may be killed or injured 
• Homes destroyed or damaged 
• Transport disrupted 
• Water and gas pipes might break; cause contamination of water or gas- fuelled fires

Economic:

• Shops and businesses destroyed 
• Looting may occur which leads into insurance claims 
• Damage to transport makes trading difficult,as well as access for emergency services

Environmental:

• Fires spread, destroy wooded areas or buildings (gas-fuelled fires)
• Current landscape destroyed, damaged or changed
• Landslides may occur, cause transport problems
• Tsunami’s might cause flooding in coastal regions