hazards -forms of hazards (tsunamis, liquefaction and landslides) Flashcards
what are tsunamis, liquefaction and landslides all examples of?
.secondary hazards of earthquakes
what are tsunamis?
.giant sea waves generated by a shallow focus underwater earthquakes
what are tsunami waves like?
.very long wavelength (sometimes over 100km)
.low wave height (<1m)
.travel very quickly (over 700km per hour)
what happens when tsunami waves approach the coast?
.they slow down and pile up as a massive wall of water before breaking
what is a drawdown?
when there is a reduction in sea level because the wave trough reaches the coast
what comes behind the drawdown?
.the tsunami wave itself
what do the effects of a tsunami depend on?
.distance the waves have travelled
.height of the waves
.shape and relief of the coastline
.land use
.population density
what percentage of tsunamis are associated with seismicity along the pacific ring of fire?
.90%
do warning systems exist?
.effective warning systems exist eg -pacific tsunami warning system based in hawaii
what is liquefaction?
.where soil starts to act as a liquid
where does liquefaction occur?
.it occurs in unconsolidated sediments that are saturated with water
what are the sediments made of in liquefaction?
.made of loosely arranged particles that are not joined together and behave like a liquid when they are shaken by seismic waves
what does liquefaction result in?
.causes objects and buildings to subside and sink into the sediments
what are landslides in terms of forms of seismic hazards
.landslides are the rapid movement of earth materials down a slope due to the ground shaking
where can landslides occur?
.fairly gentle slopes
what are the impacts of landslides?
.falling rock can kill or injure people
.block roads and hinder the efforts of emergency services
