P12 - Seismic waves

Question 1

order of Earth’s composition

Answer 1

inner core - liquid outer core - mantle - crust

Question 2

earthquake

Answer 2

-when forces inside earth increase and become strong enough to move pieces of rock(crust)

Question 3

seismic waves

Answer 3

-energy transferred makes shock waves
-travel through/across earth

Question 4

Earth’s crust

Answer 4

-earthquakes generate here
-outermost layer

Question 5

crust beneath oceans

Answer 5

thinner/younger that crust beneath continents

Question 6

focus

Answer 6

-point where earthquakes originate from

Question 7

epicentre

Answer 7

-nearest point to focus on surface

Question 8

seismometers

Answer 8

-detectors that record earthquakes on Earth’s surface

Question 9

Primary waves (P -waves )

Answer 9

-causes initial tremors lasting 1 min

Question 10

P waves are ..

Answer 10

-longitudinal
-push/pull on material as they move through Earth

Question 11

Secondary waves (S waves)

Answer 11

-cause more tremors a few mins later

Question 12

S waves are…

Answer 12

-transverse
-travel slower than P waves
-shake material that they pass through inside earth side to side

Question 13

L waves

Answer 13

-arrive last
-cause violent movements on surface
-travel the slowest
-only happen in crust layer

Question 14

P waves and S waves as they travel through mantle

Question 15

P waves at boundary between mantle/outer core

Answer 15

refraction
-speed changes here

Question 16

S waves boundary between mantle/outer core

Answer 16

cannot travel through liquid (outer core)

Question 17

shadow zone

Answer 17

area of Earth from 150. to 142. where no p waves or s waves are recorded

Question 18

prove existence of liquid outer core beneath mantle

Answer 18

-p waves are refracted at boundary (moves slower in liquid)
-second refraction cannot reach shadow zone
-s waves are transverse = cannot pass through outer core

Question 19

weak p waves in shadow zone

Answer 19

prove inner core is solid
-refracts p waves at boundary of inner/outer core

Question 20

prove boundary between crust/mantle

Answer 20

speed of seismic waves change 50km below surface - diff densities