tectonics

Question 1

explain magnetic striping

Answer 1

magnetic North and South flips over geological time
normal polarity → magnetic North = geological North
reverse polarity → magnetic North = geological South
alternates between normal and reverse
magnetic striping → zebra-like pattern of normal and reverse polarity rocks alternating (symmetrical)
due to basaltic rocks formed from iron-rich lava (contains magnetic materials)
erupts → cools → solidifies
points towards magnetic North → records polarity

Question 2

tectonic processes at O-O divergent + e.g.

Answer 2

decrease in overlying pressure
underlying mantle melts
magma rises through weak areas in crust
cools and solidifies to form new crust
forms mid-ocean ridge/rift valleys/volcanoes
e.g. North American - Eurasian → Mid-Atlantic Ridge

Question 3

tectonic processes at C-C divergent + e.g.

Answer 3

rocks fracture to form parallel faults
collapses
forms deep rift valley with steep sides
decrease in overlying pressure
underlying mantle melts
magma rises through weak areas in crust
forms volcanoes
e.g. Nubian - Somalian → East African Rift Valley + Mount Kenya + Mount Kilimanjaro

Question 4

tectonic processes at O-O convergent + e.g.

Answer 4

denser plate subducts
forms oceanic trench
subducting plates sink
high pressure forces water out
lowers melting point of overlying mantle
magma rises through weak areas in the crust
forms volcanic islands
e.g. Pacific - Philippines → Mariana Trench + Mariana Islands

Question 5

tectonic processes at C-C convergent + e.g.

Answer 5

pressure causes rocks to buckle and fold
forms fold mountains
e.g. Indian - Eurasian → Himalayas

Question 6

tectonic processes at O-C convergent + e.g.

Answer 6

oceanic plate subducts
forms oceanic trench
subducting plates sink
high pressure forces water out
lowers melting point of overlying mantle
magma rises through weak areas in the crust
forms volcanoes on continental
pressure on continental causes fold mountains
e.g. Nazca (O) - South American (C) → Peru-Chile Trench + Andes mountains

Question 7

tectonic processes at transform + e.g.

Answer 7

slide past each other
creates faults (zone of fractures)
e.g. North American - Pacific → San Andreas Fault

Question 8

formation of earthquakes

Answer 8

rocks on fault moves → locked by friction → stress builds up → exceeds rock strength → rocks snap → releases seismic waves

Question 9

list earthquake hazards

Answer 9

ground shaking, soil liquefaction, landslides, tsunamis

Question 10

earthquake hazard: soil liquefaction cause + impacts + e.g.

Answer 10

shaking causes loose soil to lose structure and transform into a thick fluid
sink trees/buildings
loose soil enters rivers
e.g. Christchurch damaged 60 000 residential buildings

Question 11

earthquake hazard: ground shaking impacts + e.g.

Answer 11

ruptures factories → pollution
uproot trees
weakens + collapses buildings
snaps water/gas/electricity pipes/cables
traps/kills from collapses
e.g. Haiti → 250 000 houses collapsed

Question 12

earthquake hazard: landslides cause + impacts + e.g.

Answer 12

loosened rocks and soil travel downhill
pollute/block rivers
bury forests/villages
e.g. Papua New Guinea → landslides
Sichuan → 15 000 landslides destroyed buildings etc.

Question 13

tsunami formation + e.g.

Answer 13

undersea earthquakes displaces seabed → lifts large amount of water → travel 800km/h to land → friction with shallow seabed slows waves, increase in height (15m or more)
e.g. Tohoku → caused 40m tsunami killed 70 000 pine trees + wildlife

Question 14

list volcanic hazards

Answer 14

tephra (ash + rocks/volcanic bombs)
volcanic gases (SO2, CO2)
lava flows (low silica)
pyroclastic flows (hot cloud of gas/ash/rocks travelling >200km/h, 700oC)
lahars (mudflows → water/rain + ash/rocks)
volcanic landslides (solidified lava)

Question 15

volcanic eruption examples

Answer 15

1991 Mt Pinatubo, Philippines (ash destroyed 800km2 of rice fields)
1979 Dieng, Indonesia (CO2 gas killed 150 people)
2018 Kilauea, Hawaii (far reaching lava flows destroyed many homes)
2010 Merapi, Indonesia (pyroclastic flows killed 350)
1950 Nevado del Ruiz, Colombia (lahars buried 20 000 people)
1980 Mt St Helens, USA (23km landslides)

Question 16

list benefits of living near volcanoes + e.g.

Answer 16

farming with fertile soil
(higher crop yields, locals earn more/larger variety)
e.g. Mt Agung, Bali grows high quality rice

minerals, fossil fuels (sulfur/copper/silver/gold)
(provides locals with income → improve economy
construction material)
e.g. Mt Merapi residents mine volcanic sand for construction

geothermal energy
e.g. Iceland’s volcanoes generate geothermal energy

tourism
(economic development, hiking/sightseeing)
e.g. Hawaiian islands volcanic landscapes → US$ 88 million annually

Question 17

list factors affecting earthquake disaster risks (nature of hazard, vulnerable conditions, exposure)

Answer 17

nature of hazard (duration of shaking, time of shaking)
vulnerable conditions (building quality, soil and rock properties)
exposure (population density, distance from epicentre)

Question 18

list factors affecting volcanic disaster risks (nature of hazard, vulnerable conditions, exposure)

Answer 18

nature of hazard (chemical composition of magma)
vulnerable conditions (water availability, prevailing winds)
exposure (distance to volcano)

Question 19

list ways to build community resilience to tectonic hazards

Answer 19

land use planning, hazard-resistant buildings, monitoring and warning systems, increasing preparedness

Question 20

building community resilience: land use planning exp + e.g.

Answer 20

reduce exposure
hazard maps (past earthquake data)
avoid development in dangerous areas
e.g. 1933 Japan tsunami → land use planning on Touni-hongo village to move coastal houses higher → 2011 Tohoku → higher ground houses not destroyed

Question 21

building community resilience: hazard-resistant buildings exp + e.g.

Answer 21

reduce vulnerability
shock absorbers/dampers
diagonal cross braces (retain building shape)
reduce collapse
e.g. Taipei 101 in earthquake prone zone → weighted damper balances out ground shaking

Question 22

building community resilience: monitoring and warning systems exp + e.g.

Answer 22

detect seismic waves and warn public
Earthquake Early Warning system
e.g. Tohoku

Question 23

building community resilience: increasing preparedness exp + e.g.

Answer 23

raising awareness through education
first-aid training
evacuation drills
e.g. Tohoku → schools educate students to evacuate disaster

Question 24

challenges in building community resilience + e.g.

Answer 24

extent of resources
organising capability
e.g. Haiti did not have community healthcare workers + no education

Question 25

disaster risk management definition

Answer 25

prevent/reduce/manage tectonic disaster risk before/during/after disasters to save lives, reduce destruction, and build community resilience

Question 26

list strategies in responding to disasters for disaster management

Answer 26

search and rescue efforts, timely evacuation, provision of basic social/psychosocial services

Question 27

disaster management strategies: search and rescue efforts exp + e.g.

Answer 27

finding/saving people trapped in disaster zones rescue more people with shortest time specialised equipment (heat sensors) reduce deaths e.g. Aegean Sea, Turkey 2020 earthquake (Mw 7.0) → 8000 search and rescue teams rescued 106 people

Question 28

disaster management strategies: timely evacuation exp + e.g.

Answer 28

earthquakes: evacuate from buildings → avoid trapped under collapse disruption of basic services → temporary shelters tsunamis: higher ground, away from coast e.g. Tohoku → 3000 Kamaishi city students evacuated → all survived volcanic eruptions: away from danger zone e.g. 2010 Mt Merapi → 700 evacuation centres saved 10 000 lives

Question 29

disaster management strategies: provision of basic social/psychosocial services exp + e.g.

Answer 29

water/food/healthcare/psychosocial services prevent dehydration/starvation/water-borne diseases help survivors cope with psychological trauma save lives of injured e.g. Haiti 2010 → International Committee of the Red Cross supplied 12 000 people with water

Question 30

challenges in disaster management + e.g.

Answer 30

lack of domestic resources e.g. Haiti → lack of resources → lack of ambulances/heavy machinery to remove rubble → wasted time manually removing rubble disagreements between stakeholders/unaware/high cost e.g. 2015 Nepal earthquake → created National Reconstruction Authority to oversee rebuilding → political disagreements took 9 months to appoint leader → hinder recovery e.g. Philippines → 10-20% insured buildings due to high insurance costs