Module 1.5 - Earthquakes

Question 1

what is an epicentre

Answer 1

point on earths surface directly above the focus point of an earthquake

Question 2

what is a focus

Answer 2

where pressure is released

Question 3

what is a fault line

Answer 3

boundary between two plates

Question 4

what is the richter scale

Answer 4

used to calculate magnitude of earthquake (+1 = x10)

Question 5

what is an earthquake

Answer 5

rapid movement of the ground caused by rapid release of energy as the tectonic plates move

Question 6

What causes an earthquake

Answer 6

earths tectonic plates are held together by friction, when this force of friction is overtaken by the force of the crust the pkates suddenly move. this jolt creates waves of energy, the ground and water shakes the the energy waves pass through them

Question 7

what is a seismic wave

Answer 7

vibrations that travel through earth caused by earthquakes

Question 8

in what direction do primary waves shake (longitudinal or transverse)

Answer 8

longitudinal (back and forth)

Question 9

at what speed do p waves travel , what medium can p waves travel through and what level of destruction is created

Answer 9

8km/s (fasted wave type)
travels through liquid and solid
level of destruction: low

Question 10

in what direction do secondary waves shake (longitudinal or transverse)

Answer 10

transversal (up and down - opposite to way the wave hits)

Question 11

at what speed do s waves travel , what medium can p waves travel through and what level of destruction is created

Answer 11

4.5km/s (second fastest - comes in after p wave)
only travels through solid
level of destruction : Medium

Question 12

in what direction do surface waves shake

Answer 12

in circular motion

Question 13

at what speed do surface waves travel , what medium can p waves travel through and what level of destruction is created

Answer 13

no speed quoted
travels only through the the very top of earths surface
level of destruction HIGH

Question 14

why do waves follow a curved path

Answer 14

shock waves spread in al directions from focus

Question 15

why do waves suddenly change directions

Answer 15

shock waves are refracted off different substances

Question 16

How do S waves relate to the structure of the earth

Answer 16

s waves can’t go through liquid meaning that the waves cannot penetrate the cores outer liquid

Question 17

Explain australias intra plate earthquakes

Answer 17

australia is not on a plate boundary but when the indo australian plate is being pushed North and is colliding with the eurasian, Phillipine and pacific plates we feel earthquakes because eventually a build up of stress inside our plate is let out and thats how we feel it.

Question 18

what is a tsunami

Answer 18

long high waves caused by sudden movement of the ocean floor due to earthquakes, landslides and earthquakes

Question 19

what causes tsunamis?

Answer 19

caused by undersea earthquakes where a plate boundary rises or falls displacing the water above and creating fast ripple waves that travel at 800km/s. As the floor becomes shallower the wave slows down and whilst doing so the fast ripples behind them collide and become larger and inundate the land.

Question 20

What is the effect of tsunamis

Answer 20

trough sucks the tude back in and 5 mins later a series of gigantic waves come