earthquakes CH3 Flashcards
define, tremor?
a vibration in the earths crust
define, seismic wave?
energy radiating from the focus of the earthquake
define, focus?
the underground origin of the earthquake
define, epicentre?
the point on the surface directly above the focus
define, seismograph?
an instrument used to measure earthquake magnitude
define, Richter scale?
a scale used to measure earthquake magnitude
define, mercalli scale?
a scale used to measure earthquake intensity
define, after shock?
small tremor that occurs after a major earthquake
where do earthquakes occur?
plate edges, San Andreas fault and pacific ring of fire
explain shallow focus? (type)
focus is up to 80km deep, most common, causes most damage
explain deep focus? (type)
focus is deeper than 100km deep, chemical changes in rock, creates less damage as energy is lost
explain, briefly how earthquakes are triggered at convergent plate boundaries?
2 plates collide, friction causes them to lock together, pressure builds up over years until the rock breaks and causes a slip causing earthquakes
explain how liquefaction occurs?
the shaking of the ground during an earthquake causes the soil to become saturated
what tectonic activity occurs along the subduction zone?
volcanic activity
what causes earthquakes?
earthquakes occur when destructive or conservative plate boundaries move past each other. Pressure builds up from active convection currents and eventually the pressure is released, forming an earthquake
