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earthquakes (natural hazards) - Coggle Diagram
earthquakes (natural hazards)
types of seismic waves
primary waves: fast low frequency waves, passes through liquid and solid
secondary waves: slow high frequency waves , stopped by liquid
surface waves: slowest low frequency waves, travel through outer crust only
where do earthquakes occur
mid ocean ridges
ocean trenches and island arcs
collision zones
conservative plate margins
Rift Valleys: lowland region that forms when earths plates move apart. Are found on land and at the bottom of the ocean where they are created by the process of seafloor spreading
types of earthquakes effects
ground shaking/ ground displacement
severitiy of this can depend on the magnitude, distance from the epicentre
tsunamis
liqufraction
takes place when loosely packed water clogged ground lose their strength
landslides and avalanches
Focus
deep focus
70-700km
poorly understood
do not do as much damage as shallow
more powerful
shallow focus
0-70km
very common
do serious damage
not as powerful but cover a wider range of area
assessing earthquakes
richter scale
Uses the amplitude of seismic waves to determine earthquake
magnitude
modified mercalli scale
measures earthquake impact and intensity
moment maginitude scale