understanding earthquakes

Question 1

benioff zone

Answer 1

area of seismicity corresponding with slab being thrust down in the subduction zone (at destructive boundary

Question 2

fault

Answer 2

fracture in rocks which make up the earths crust

Question 3

locked fault

Answer 3

a slip due to built up strain (not friction between plates)

Question 4

focus / hypocentre

Answer 4

point in crust where the seismic waves originated from

Question 5

epicentre

Answer 5

point on earth’s surface above the hypocentre

Question 6

seismic waves

Answer 6

type of wave which causes shaking

Question 7

3 types of seismic waves

Answer 7

primary (compressional)
secondary (shear)
love (surface waves)

Question 8

sequence of an earthquake

Answer 8

strain, pressure exceeded, release, rebound

Question 9

2 primary hazards of an earthquake

Answer 9

ground shaking, crustal fracturing

Question 10

ground shaking

Answer 10

movement of the ground due to the P,S and L waves in less than 60 seconds, causing buildings to be damaged if they are not aseismic

Question 11

what does aseismic mean

Answer 11

earthquake proof

Question 12

crustal fracturing

Answer 12

shockwaves in solid rock increases stress and causes rock fractures and faults - damaging building above

Question 13

3 secondary hazards of earthquakes (physical)

Answer 13

soil liquefaction
landslides and avalanches
tsunami

Question 14

soil liquefaction

Answer 14

loose rock and sediment causes buildings to settle/tilt/collapse worsened in river areas and sloping ground as building sink due to soil instability

Question 15

landslides and avalanches

Answer 15

mag 4+, areas of land collapse due to shaking (often if land is saturated)

Question 16

tsunamis

Answer 16

caused when plate rebounds and a water displacement is created, can devastate areas due to high amplitude, fast velocities

Question 17

which causes more deaths, primary of secondary hazards

Answer 17

secondary -> 70% of all deaths are due to secondary earthquakes

Question 18

P waves info

Answer 18

longitudinal, 8km/s and travel through solid and liquid
smaller wl, high frequency

Question 19

S waves info

Answer 19

transverse, 4km/s only travel through solids and are slower but are very destructive

Question 20

L waves 2 types

Answer 20

love = move side to side
raleign = like a roll (up,down,up etc)

Question 21

L waves info

Answer 21

largest at the surface and decrease in amplitude at depth, are very destructive