10 - Secondary hazards of earthquakes Flashcards
1
Q
how are tsunamis generated
A
movement of sea floor which significantly moves the water column
2
Q
how does water depth affect wave speed and amplitude
A
- tsunami speeds depend on water depth
- A wave going from deep to shallow water decreases velocity and increases amplitude
3
Q
what is the minimum magnitude for an tsunami to form
A
7.5
4
Q
how are tsunamis recorded
A
- tidal gauge records - wave arrival at the coast
- ocean buoys ad pressure gauges
- satellite observations of sea surface elevation
5
Q
how can tsunamis be seen in geological records
A
- evidence of erosion or deposition
- unusual deposits în coastal regions
- marine deposits in terrestrial environments
- erosional and filled channels
6
Q
what is liquefaction
A
soft sediment with high water content can liquefy when shaken
7
Q
how does liquefaction occur
A
bonds between sediment particles is lost
8
Q
how can earthquakes cause landslides
A
- direct shaking and destabilisation
- indirect liquefaction
- loading due to tsunami wave
