seismic hazards

• Ground movement - upward acceleration of ground may throw objects upwards. 
• Building damage - ground movement separates structures, floors break from walls and pancake on top of each other. Pipes my break apart. Buildings may sway on their foundations. 
• If buildings natural frequency matches the earthquake - sway increases by resonance. The resonance depends on height and shape of buildings. 
• Landslides - steep unstable slopes can be triggered to slip by vibrations, bury roads and buildings. 
• Liquefaction - vibrations within loose sediment separates the sand, silt and water and rises to the surface. The ground loses its strength and makes it behave like quicksand. Buildings sink, subside and topple over. After shaking stops the ground returns to normal. Houses built on river deposits or lake deposits are at risk. 
• Aftershocks from the main movement along fault releasing energy and subsequent movement in the time after cause aftershocks. Previously weakened structures can collapse, rescue work is hindered. 
• Damage to infrastructure like railways, bridges and multi tiered freeways. 
• Fires caused by short-circuiting of power lines, and gas pipes fractured. Lack of water from breakage of water pipes to combat fires. Wooden buildings are most susceptible.
• Seiches are when bodies of water cause overflow and oscillations during seismic events. Lakes have reached wave sizes up to 10 metres.