Tectonic plates and hazards

Question 1

explain the distribution and cause of tectonic hazards

Answer 1

plate boundaries often move in different directions at different speeds creating a variations of plate boundaries which leads to variations in earthquake and volcanic activity

Question 2

what is a divergent plate boundary

Answer 2

this is when the two plates move towards each other and one plate gets subducted which can cause earthquakes and volcanoes
eg: Nazca plate forced under south american plate

Question 3

What is a convergent/collision plate boundary

Answer 3

this is when two plates move towards each other and collide forming mountains and tends to be continental rock eg: the himalayas

Question 4

what is a constructive plate boundary

Answer 4

this is when the plates move apart from each other which can lead to creation of new crusts and when in the sea it can form new sea ridges
eg: pacific plate moving away from nazca plate

Question 5

what is a conservative plate boundary

Answer 5

this is when two plates slide past each other and due to the friction this tends to form earthquakes eg: San andreas fault

Question 6

what is convection

Answer 6

convection is when magma rises due to the heat and it being less dense causing denser and colder material to sink this tends to help volcanoes

Question 7

what is mantle convection

Answer 7

heat produced by radioactive decay heats the lower mantle creating convection currents within the asthenosphere causing plate movements

Question 8

explain sea floor spreading

Answer 8

judge mid ocean ridges formed (constructive) and magma is forced up and hardens forming new oceanic crust causing the sea floor to spread and push the tectonic plates apart

Question 9

what is subduction

Answer 9

when two plates move towards each other one slides underneath the other causing a subduction zone

Question 10

what is a slab pull

Answer 10

newly formed oceanic material at mid- ocean ridges become denser and thicker as it cools causing it to sink into the mantle pulling the plate down (helps subduction)

Question 11

what are intra plate earthquakes

Answer 11

these occur in the middle (interior) of plates and their cause is most likely stresses from scientists faults becoming active again they have a random distribution

Question 12

explain the distribution of hotspots

Answer 12

these can be found near the centre of some plates due to upwelling if the hot molten material form the core eg: hawaiian plate
or it can be caused by mantle plumes just under the crust heating the surface above it eg: cape verde islands

Question 13

what is palaeomagnetism

Answer 13

this is a theory form the supercontinent pangaea and how you can find the same rock types at different coasts eg: south africa and south america and this is due to the magnetic field where either side of the plate the rocks ‘lock in’ forming the same pattern of rocks on either side

Question 14

what are primary waves

Answer 14

primary waves arrive first and move through solid rock and fluids, they move in a push and pull motion

Question 15

what are secondary waves

Answer 15

slower than P waves and only move through solid rock. They move in an up and down motion

Question 16

what are Love waves

Answer 16

the only travel through the surface of the crust and are fast. They move from side to side

Question 17

what are 3 secondary impacts of earthquakes (include examples)

Answer 17

tsunami- japan 2011 (powerpoint & 15,000)
landslides- movement of severe and rocks faking creating hazards such as road blockage kashmir 2005
liquification- sediments in ground become loose due to shaking. christchurch new z had a shallow earthquake 5.95 on which exaggerated liquification

Question 18

primary factors from earthquakes

Answer 18

crustal factoring

ground shaking creating hazard

Question 19

how are tsunamis formed

Answer 19

these tend to be formed when submarine earthquakes at subduction zones as a result of water column displacement

Question 20

describe balsatic lava

Answer 20

hottest lava (1000-1200)
runny and thin
found at shield volcanoes & ocean hotspots
gentle eruptions

Question 21

describe andestitic lava

Answer 21

around 800-1000

slow flowing however eruptions are moderately powerful

Question 22

describe rhyolitic lava

Answer 22

coolest lava (650-800)
very high viscosity
has most violent eruptions
found at compositivo volcanoes/ super volcanoes

Question 23

describe a shield volcano

Answer 23

found at hotspots or convergent boundary
erupt frequently but not that powerful
balsatic lava

Question 24

describe a composite volcano

Answer 24

found at destructive plate boundary
erupt infrequently however are very powerful
andesitic/rhyolitic lava

Question 25

primary impacts from volcano/lava

Answer 25

lava flows: streams of lava move slowly from volcano and can take years to cool however because they’re so slow they’re not that hazardous to humans example: kilauea volcano, Hawaii pyroclastic flows: consist of dense rock and lava flowing very quickly (100km) from volcano impossible to get away from making them very hazardous eg: mount sinnabung

Question 26

secondary impact of volcano

Answer 26

lahars: these are masses of rock, mud and water that vairy in size and speed, they occur when eruption occurs on ice/snow eg: jokulaud

Question 27

describe a few impacts of tsunamis

Answer 27

they can travel several miles inland sweeping away buildings, trees and bridges they can change the landscape of small islands/ completely destroy them cause drowning, buildings to collapse on people and flooding can cause contamination to food and water leading to illnesses

Question 28

how do you detected tsunamis?

Answer 28

DART sensors are used to monitor changes in sea level | japan is known for having the most extensive warming system for tsunamis in 2011 there was a warning within 3 minutes

Question 29

describe an earthquake event for a developing country

Answer 29

Haiti: January 12th magnitude 7 (13km) impacts: half a million deaths this earthquake turned into a disaster due to: because it isn’t very wealthy money was spent on reducing poverty rather than earthquake preparation high levels of government corruption reduced improvements to buildings and living standards poor buildings due to lack of building regulations high population density few peephole knew what to do due to lack of earthquake prep RECOVERY In 2016 Haiti was still recovering and $13 billion was donated to help however other countries were hesitating due to the corruption in the government IMPROVEMENTS despite 80,000 being in temporary homes (2015) new roads, buildings and schools are slowly being built along with health statistics improving and a stronger government

Question 30

describe an earthquake for an emerging country

Answer 30

CHINA earthquake magnitude 7.9 on 12th May 2008 in SICHUAN IMPACTS Over 45.5million were effected (70,000) deaths and 5 million made homeless landslides caused 25% of deaths 300,000 injuries in Sichuan the location was quite rural = fewer deaths china is wealthier (than haiti) meaning they could ph for rescue efforts medical services restored preventing disease government gave $10billion for rebuilding within 2 weeks temporary houses, roads and building were being built BECAUSE CHINA HAD A STRONGER GOV they had tougher building codes and regulations which helped with responding to the event RECOVERY they rebuilt affected areas in 2 years (however several days passed until oversea help was accepted)

Question 31

Describe an earthquake in a developed country

Answer 31

JAPAN March 11 2011 magnitude 9 earthquake struck PRIMARY IMPACTS: seawater displacement caused 10m high tsunami along with surges Nuclear power plant was severely damaged releasing dangerous levels of radiation forcing evacuation of 47,000 people yet despite this japan had no deaths and few injuries PREPARATION japan had financial resources to prepare for hazards such has strict building regulations meaning their buildings could withstand earthquakes (low levels of corruption also helped) earthquake education and practise drills (well developed disaster plans eg: 10m tsunami wall) NUCLEAR PLANT RESPONSE: electricity prices increased by 20% government debt rose green house emissions increased

Question 32

ice land case study

Answer 32

eyjafallajokull april 2010 no deaths ash clouds affected northern europe for a week 100,000 flights cancelled affecting 10 million people airlines lost $1.7 billion crops destroyed from ash

Question 33

typhoon hiyan

Answer 33

category 5 November 2013 at 4:30 am primary impacts: homes destroyed ross blocked by debree 5m storm surge - 400mm rainfall 7000 deaths 14.1 million people effected million tons of crops destroyed secondary effects: survivors had to fight fro food causing 8 people to die sea water and sewerage systems contaminated responses: 800,000 people evacuated (refugee stadium flooded) mangroves planted and storm surge warning system put into place for future