Damage from earthquakes The specification states that you need to know about: Social and economic impacts: Types of ground movement, damage to structures, liquefaction, landslips, tsunamis and aftershocks.

Earthquakes Be aware of the difference between seismographs and seismograms. Seismograph is the instrument that measures seismic waves. A seismogram is the record produced by a seismograph.

Earthquakes You should be able to appreciate the social and economic effects of earthquake activity. How the ground moves. Damage to structures. Liquefaction. Landslips. Tsunamis. Aftershocks.

Ground Movement As you know there are 3 main groups of seismic wave. They all move in a different fashion as seen in the diagram. Which kind causes the most surface damage? L waves because they are concentrated at the surface and have relatively long wavelengths which destroy buildings.

Damage to structures This occurs because the ground moves but most buildings are rigid and so the structures fracture and collapse. Not only buildings but supports for roads, bridges etc.

Liquefaction

Landslips Just like earthquakes disrupt buildings and cause liquefaction they can also make the ground unstable especially if: The sediment is loose and saturated. The rocks include saturated shales/mudstones/clay s. If the rocks dip down slope.

Tsunamis Tidal waves. These are caused as the sea bed moves due to seismic wave movement (or landslips into the sea). This causes displacement of water which forms a tsunami. The tsunami becomes a problem when the wave enters shallow water and steepens up.

Aftershocks It is almost inevitable that there will be smaller but still often significant earthquakes after the main shocks. This means that already weakened buildings may then collapse.