7 - Intro to earthquakes Flashcards
what is an earthquake
the release of accumulated elastic strain causes rupture of rock along a fault
what is the epicentre
location of earths surface immediately above the point of first energy release
what is the hypocentre
location within the earth where first energy if released
what is the focal depth
the depth of the earthquake below the earths surface
what are the different focal depths of earthquakes
shallow 0-70km (most common)
intermediate 70-300km (subduction zones)
deep 300-700km
what are the different shocks of an earthquake
foreshock - shock that occurs before an earthquake
main shock - main event of earthquake
aftershock - shocks that occur in the surrounding area after a big earthquake
where do earthquakes occur
usually close to plate boundaries and most common at <70 km, except at subduction zones (700-800km)
what factors effect earthquake fatalities
magnitude, depth, location compared to people, secondary impacts (e.g. tsunamis)
what are natural secondary hazards of earthqueakes
- ground shaking/failure
- landslides/avalanches
- mud flows
- liquefaction
- tsunamis
what are anthropogenic hazards of earthquakes
- damage to infrastructure
- floods from dams and pipes
- filing objects
- disruption to transport, communications, power, water supply and sewage
- radioactive leaks
