Primary effects are the immediate damage caused by the quake, such as collapsing buildings, roads and bridges, which may kill many people. Those lucky enough to survive can suffer badly from shock and panic.
Secondary effects are the after-effects of the earthquake, such as fires, tidal waves, landslides and disease.
Fire – earthquakes destroy gas pipes and electric cables, causing fires to spread. Broken water mains prevent the Fires being extinguished. Fires spread very quickly in cities, especially in poor-quality housing areas where wooden buildings are common. Tsunamis – an earthquake on the sea floor or close to the coast may cause huge waves. Landslides – earthquakes often cause landslides, especially in steep river valleys and areas of weak rocks. Disease and famine – fresh water supplies are often cut off causing typhoid and cholera. Lack of shelter and food causes much suffering. soil liquefaction when soils with a high water content are violently shaken they lose their mechanical strength and behave like a fluid and so buildings can literally sink. Excellent clip 2011 Japan Tsunamis
Mega tsunami caused by a landslide July 9th 1958
Outline causes A tsunami can be generated when destructive plate boundaries abruptly move and vertically displace the overlying water. It is very unlikely that they can form at constructive or conservative plate boundaries. This is because constructive or conservative boundaries do not generally disturb the vertical displacement of the water column. Subduction zone related earthquakes generate the majority of all tsunamis. Tsunamis have a small wave height offshore, and a very long wavelength (often hundreds of kilometers long), which is why they generally pass unnoticed at sea, forming only a slight swell usually about 300 mm above the normal sea surface. and they travel quickly at speeds over 700 km/h. They grow in height when they reach shallower water.