Introduction to earthquakes and related hazards Flashcards
How do Tsunami waves form?
Subudction induced earthquake under the sea causes energy release into the sea
High energy waves slow doen as they approch the shore
But they do increase in height
How do tsunamis affect peoples livelihoods?
Huge infiltration of saltwater damages crops
Takes a long time for ground to recover
Causing long term/permanent displacement
Why are the impact of tsunamis so significant?
Effects can be far reaching relative to the location/source
What is the typical speed of a tsunami wave in deep water?
200 m/s
Can tsunamis be predicted?
Prediction is possible for distal locations e.g. Pacific Tsunami Warning centre
Improved technology and modelling techniques advance prediction of wave heights
Where do the largest earthqaules normally occur?
Subduction zones
Like the ones in the Pacific ring of fire
What is the equation to work out seismic moment (magnitude)?
Slip of fault * area of fault plane
Why are volcanic earthquakes smaller than tectonic ones?
They involve a lot less energy
What are some examples of anthropogenic produced seismic events?
Explosions and seismic surveys
Heavy traffic
Reservoir and fluid injeection induced earthquakes
Mining-induced earthquakes
What is the definition of an earthquake?
The release of accumulated elastic strain, causing a rupture of rock along a fault
What is the definition of the epicentre?
The location on the earth’s surface above the focus of the earthquake where the energy is released first
What is the definition of strain?
Measure of the amount of deformation that the rock has experienced
What is the definition of stress?
The force acting (per unit area) on any defined plane within the volume of rock
What is the depth of a shallow earthquake (most damaging)?
0-70km
What is the depth of intermediate earthquake?
70-300km
