Earthquake

Question 1

Earthquakes at convergent boundaries

Answer 1

Most powerful earthquakes occur along subduction zones, plates to lock from friction, pressure breaks rock. The subducting plate suddenly sinks => violent earthquake.

Question 2

Oceanic - continental

Answer 2

2011 Japanese earthquake => sudden movement of Pacific plate under Eurasian plate. Eurasian plate pushed up =>tsunami, power plant meltdown

Question 3

Continental - Continental

Answer 3

2015 Nepal earthquake Indo-Australian + Euasian 7.8. 2 plates collide, rock layers buckle up, pressure =friction, plates lock together.
The pressure builds rock breaks - sudden movement
shallow focus-highly destructive.

Question 4

Earthquakes at diverging boundaries

Answer 4

Mozambique earthquake 2006
crust rifts apart and plumes of magma rise, causing vibrations, elastic rebound => strong earthquake

Question 5

Elastic rebound

Answer 5

Rocks stretches until it breaks + snaps back, releasing loads of pressure

Question 6

Earthquakes at transform boundaries

Answer 6

San Andreas fault Pacific + North American
plates slide past, friction = lock, pressure builds until rock breaks + plate jolts up => earthquake.

Question 7

P waves/ primary waves

Answer 7

1st
travel through anything
no damage

Question 8

S waves/ secondary waves

Answer 8

2nd
Only travels through rock
Crust moves up + down, ground shakes

Question 9

Surface waves

Answer 9

Closest, so causes almost all damage
Crust moves up, down + side to side

Question 10

Richter Scale

Answer 10

Records readings from seismograph.
Begins at 0 -no upper limit.
Logarithmic scale – e.g. 2.0 is 10 × stronger than 1.0.

Question 11

Moment magnitude scale

Answer 11

Most common + accurate
Seismograph + amount of rock movement at fault.
logarithmic scale.

Question 12

Mercalli scale

Answer 12

Subjective
12 grades- Roman numerals

Question 13

Predicting earthquakes - Strainmeters

Answer 13

Monitor rock stress
holes 200m deep in ground, tells when rock will break

Question 14

Predicting earthquakes - Tiltmeter

Answer 14

Shows change in slope from increased rock pressure

Question 15

Predicting earthquakes - Seismometer

Answer 15

Records horizontal + vertical crust movement, is placed at fault lines

Question 16

Predicting earthquakes - Gas emmisions

Answer 16

Radon is released, radioactive so easily detectable, but tells us nothing about time/location

Question 17

Predicting earthquakes - Animal behaviour

Answer 17

Animals can sense P-waves

Question 18

2011 Japan Earthquake - the earthquake

Answer 18

11 March 2011 9.0 magnitude 72 km off Japanese coast for 6 mins. Pacific subducted, Euarasian went up - megathrust.
Focus 24km below ocean floor, whch rose 10m=> tsunami which travelled 10km inland

Question 19

2011 Japan Earthquake - Effects

Answer 19

15,897 killed
120,000+ buildings destroyed
1.5 million without safe drinking water

Question 20

2011 Japan Earthquake - Powerplant

Answer 20

Generators at the Fukushima Daiichi Nuclear Power Plant generators flooded – cooling system fails-reactors overheat =>20 km radius evacuation zone

Question 21

2011 Japan Earthquake - Aftermath

Answer 21

Early warning system upgraded.
€200 billion to the Japanese economy.
Radiation still being released into the Pacific

Question 22

Earthquake negative effects - Infrastructure damage

Answer 22

Seismic waves make buildings + bridges to sway + collapse.
Falling debris crushes + suffocates people => significant loss of life

Question 23

Earthquake negative effects - tsunami - how it works

Answer 23

1 plate rises, other subducts=> excess water hump spreads out in all direcions u to 970km/h. When tsunami hits land, friction slows it + quadruples in height before crashing

Question 24

Earthquake negative effects - Liquifaction

Answer 24

Groundwater water saturates soi until it liquifies, can’t support anything, so buildings collapse + pipes sink/break

Question 25

Earthquake damage factors

Answer 25

Magnitude - bigger earthquake - worse
Depth -shallow = seismic waves have more energy.
Developing versus developed countries - richer countries can afford better infrastucture.
Time of day - more people out- more people crushed
Population density -more people, more dead
Geology - loose soil liquifies more

Question 26

Earthquake proof buildings

Answer 26

Slightly elastic - sways
Built on rock - no liquefaction
Shock absorbers
Steel “birdcage” holds it together + lets it sway
Weights on the roof let it sway