tsunamis

• •  submarine earthquake 
  • Volcanic eruptions 
  • Major landslides 
  • Asteroid impacts 
• Submarines earthquakes at convergent boundaries where subduction of ocean plates is occurring. Stress builds up when plates are locked together. Over-riding plate deforms as stress builds. Earthquake occurs and stress releases - elastic rebound of plate releases energy and generates tsunamis. 
• Out at sea energy is spread throughout water column. As approaching the shore wave shoaling happens - energy is restricted into smaller volume, the wave slows and height increases. Bays and inlets increase height even more. 
• Alaska landslide:

  Fairweather fault moved and loosened millions of cubic meters of rock which fell into the gilbert inlet. Generated a tsunami with a wave height of 524 metres. 
• Landslide tsunamis have the potential to generate much larger waves than earthquake tsunamis. 
• Volcanic eruptions can trigger landslides which have the potential to generate tsunamis. During the Krakatoa eruption 36000 people dies due to the volcanic tsunami. 
• Asteroid impacts can trigger tsunamis. 
• The weight and force of water tears buildings apart and washes away topsoil, undermining bridges and buildings. 
• Salt water can contaminate farmland and groundwater. 
• Papodopoulos Imamura is the 12 point intensity scale for tsunamis. Based on effects on humans, objects and damage to buildings.