Earthquakes Flashcards
where and why do earthquakes occur?
occur in a linear belt along plate boundaries
occur due to movement along the earths crust
what are earthquakes?
ground shaking by the fracturing of rocks and sudden movement along fault lines
what is an earthquakes focus?
the precise location of an earthquake within the crust
what is the epicentre?
the point on the surface immediately above the focus
what are the secondary hazards of earthquakes?
shockwaves and seismic waves
tsunami
liquefaction
landslide
what is liquefaction?
when violently shaken soils with a high water content lose their mechanical strength and become fluid
what is a landslide?
there is slope failure as a result of ground shaking and the land slides/slips
what is the global distribution of earthquakes?
- a clear line of earthquakes along the centre of the atlantic ocean between african and american plate and around pacific ocean at edge of pacific plate
- conservative plate boundaries where plates are sliding past each other
some earthquakes occur away from plate boundaries and are associated with…
the reactivation of old fault lines
isolated plumes of tectonic activity are known as
hot spots
what is the magnitude of earthquakes measured by?
the rhictor scale
moment magnitude scale
mercalli scale
prediction can be difficult regions at risk can be identified attempts to predict include…
monitoring groundwater levels
release of radon gas
strange animal behaviour
measuring of magnetic fields
prevention of seismic events…
prevention of seismic natural hazards is impossible
making sure that the population of areas at risk is well informed regarding protection and safety during seismic hazards is essential measures include…
- ensuring safety drills are well practiced
- building of hazard resistant structures
- fire prevention - smart meters
- careful education, training and preparation of emergency services
- land use planning - putting certain types of buildings in low-risk areas
- tsunami protection - warning systems
