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hazardous environments Flashcards

1
Q

distribution of earthquakes

A

at collision (intense), constructive (shallower), destructive (extreme), conservative (powerful)

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2
Q

distribution of volcanoes

A

at constructive and destructive (more extreme) plate boundaries

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3
Q

distribution of tropical cyclones

A

between 5 and 30 degrees around the equator because they need fuel (water) and temps of 27 celsius

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4
Q

primary characteristics of earthquakes

A

focus: the point within the earth where the earthquake starts
epicentre: the area directly above the focus, typically experiences the most severe shaking
impacts:
- soil liquefaction: saturated soils turn to liquid because pressure is relieved due to shakes, making the soil lose load-bearing strength. causes flooding and sink holes
- ground shaking: caused by energy released from rocks during earthquake, measured in velocity, acceleration and frequency. poorly consolidated rock increase amplitude, duration and damage. destroys buildings and infrastructure
- surface rupture: fault extends to earths surface, structures can be torn apart
- mass movement: saturated material creates mud flow, which destroys paths, prevents aid and floods. landslides triggered by 4.5 earthquakes, isolates and destroys

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5
Q

characteristics of volcanoes

A

lava bombs: large fragments of partially melted rock ejected from volcano, usually solid in he air
pyroclastic flows: fast moving avalanche of hot volcanic ash, gas and rock down slopes, can bury or burn
lahars: slurry of volcanic debris and water that flows down side of volcano, like a mud flow
lava: hot, fast flowing, hard to stop

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6
Q

characteristics of tropical cyclones

A

storm surge (P): surges of water up to 3m high, flood low lying areas
strong winds (P): over 120 km/h, tear off roofs, break windows, inhibit communication and transport
intense rainfall (P): short-term flash floods, slower river flooding.
coastal erosion (S): houses near beach destroyed, affects tourism
damage by wind blown/ washed up debris: sand destroy buildings and infrastructure
landslide/ mud flows : fast, buries things, hard to get away from

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7
Q

measurement of earthquakes

A

seismometers record ground motion, then put on Richter scale (10 most dangerous), higher less common
moment magnitude scale, like Richter scale but has a wider range of magnitudes and is more accurate

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8
Q

measurement of volcanoes

A

volcanic explosivity index, logarithmic

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9
Q

measurement of tropical cyclones

A

saffir-simpson hurricane wind scale, defining speed and impacts. up to category 5

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10
Q

causes of tropical cyclones

A

warm water (at least 27), low wind shear (to allow winds to circle), high humidity.
formed: air above water heated, making the air rise quickly which creates an area of very low pressure. air continues to rise quickly, sucking up more warm moist air from the water leading to strong winds. the rapidly rising air spirals up, condenses and falls. large cumulonimbus clouds form, forming the eye wall, creating heavy rainfall. cold air sinks down eye.
Coriolis effect: earths rotation leads to cyclones spinning counterclockwise in northern hemisphere, clockwise in southern.

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11
Q

volcanic and earthquake hot spots

A

volcano hotspots: formed away from plate boundaries, plume of superheated rock rises through mantle. rises through weaknesses in the crust (caused by melting) and erupts at surface
earthquakes: regions with high intensity of earthquakes, along tectonic boundaries

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12
Q

composite volcano

A

formed: destructive boundaries. alternating layers of ash and lava. infrequent extreme eruptions
shape: tall, steep sided, conical with narrow base
characteristics: high viscous lava with high silica content and gas bubbles, unable to run far. violently explosive
hazards: lahars, lava bombs, pyroclastic flows

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13
Q

shield volcano

A

formed: constructive boundaries and hotspots. only made of lava. frequent effusive eruptions.
shape: gently sloping, wide base
characteristics: low viscous lava, low in oil;ica so runs like honey. able to travel long distances. low explosivity
hazards: lava flows

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14
Q

plate boundaries

A

conservative, constructive, collision and destructive

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15
Q

why do plates move

A

rock is heated in the lower mantle near the core.
this rises towards the top.
it cools there and is forced sideways by more rock.
continues to cool and sinks back to core, creates convection current.
process continues.

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16
Q

secondary characteristics of earthquakes

A

tsunami: plate shift displaces water, waves move out in all directions. waves enter shallower water and compress and slow to build in height. can cause flooding.
fire: ruptured electricity equipment

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17
Q

conservative boundaries

A

two plates move in opposite directions, rub against each other. they jam due to getting stuck on rock etc. tension builds, until pressure is released, causes sudden jolt.
extreme earthquakes

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18
Q

constructive boundaries

A

two plates move away from each other due to convection currents. magma rises, leads to pressure and doming of crust. magma breaks through, causing earthquake. magma builds up to form volcanic islands/ shield volcanoes. lava ridges also formed.
gentle volcanic eruptions, small earthquakes, shield volcanoes

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19
Q

destructive boundaries

A

oceanic and continental crusts move towards each other.
oceanic plate subducts under continental, as its denser.
increase in pressure and temp causes oceanic to melt, creating magma which leads to volcanic eruptions.
ocean trench, composite volcano, earthquakes

20
Q

collision boundaries

A

2 continental plates move towards each other. because of same density, little subduction occurs. so rocks at plate boundary crumple to form fold mountains.
fold mountains
earthquakes

21
Q

why do people continue to live in areas at risk from hazards

A
  • fertile soil from volcanoes
  • fault lines from earthquakes provide drinking water
  • tourism
  • tradition/culture
  • people living in poverty have other troubles to think about/cannot move anyway
  • may think chance of a hazard is low
  • cheaper housing
  • cheap geothermal energy
  • valuable materials
  • people don’t want to leave family
    megacities often in hazardous areas
22
Q

mindsets of people living in hazardous areas

A

fatalistic: it might happen, just part of life
adaptation: events can be prevented or predicted/ adapted to
acceptance: its a part of life and there are certain advantages

23
Q

relationship between megacities and hazards

A

megacities often in hazardous areas
because of tourism, access (water etc), cultural values
increase damage as more investment has been put it/ more people live there
people stay for the economic influence, sentimental value, inability to move, investment

24
Q

why are some countries more vulnerable to impacts of natural hazards

A

economically: LICs have less money for prediction, prevention, rebuilding and adaptation
socially: informal housing, ageing population, urbanisation. population density, conflict, building quality
physically: hotspots, oceans, rivers, dry or wet areas. plate boundary, type of rocks, time of day/week, secondary hazards

25
poverty effect on vulnerability
informal housing without proper safety measures can lead to more deaths can't educate people can't build safety precautions
26
agriculture effect on vulnerability
floodplains are more fertile, but have a higher chance of flooding soil around a volcano is fertile but is dangerous
27
urbanisation effect on vulnerability
more people means more informal housing and less infrastructure such as shelters, hospitals, schools larger buildings or crowded buildings can fall on people easily
28
climate change effect on vulnerability
higher frequency and extremity of events
29
case study: impacts of a volcano
Eyjafjallajokull volcano Facts: 20th March, 2010, first eruption in 190 years. erupted under ice sheet- meltwater flowed into volcano, vaporised and increased explosivity
30
case study: impacts of an earthquake
Haiti earthquake facts: 12th jan, 2010, 7.0 magnitude.
31
case study: impacts of a cyclone
Typhoon Haiyan Facts: 7-8th November 2013, late afternoon. started on the 2nd and developed into a full storm on the 4th. most powerful tropical storm ever recorded. storm surges of up to 15 feet, floods to 20
32
social impacts of typhoon Haiyan
primary: 7500 dead, 9m affected. over-crowded hospitals. secondary: humanitarian crisis- 1.9m homeless and 6m displaced. less affected areas' populations doubled after influx
33
economic impacts of typhoon Haiyan
primary: major rice and sugar producing areas were destroyed. 50,000-120,000 tons of sugar lost. 131,000 tons of rice lost. 71,000 hectares of farmland destroyed. looting. secondary: $12bn in damages. coconuts count for half the Philippines exports, they are biggest producer
34
environmental impacts of typhoon Haiyan
primary: loss of forests, trees and widespread flooding. oil and sewage leaks into ecosystems. coconut plantations completely flattened. fishing communities destroyed. secondary: lack of sanitation leads to pollution
35
political impacts of typhoon Haiyan
primary: Philippines declared a state of national calamity and asked for aid secondary: UN too slow to act. president Aquino criticised for slow distribution of food and water. government decreased from 2,500 to 70.
36
social impacts of Eyjafjallajokull volcano
primary: lava flows destroyed roads. volcanic gases cause irritation for local residents. tephra falls covered pastures, houses, farms. 700 evacuated.
37
social impacts of Haiti earthquake
primary: roads and docks in Port-Au-Prince closed, hard to deliver water and food. 300,000 dead. 19m cubic metres of rubble and debris. 4,000 damaged. 105,000 houses destroyed. 1.5m living in camps. secondary: 1 in 5 jobs lost. cholera outbreak killed 6,000- due to lack of clean water and dead bodies. doctors had to do surgeries outside-over flowing hospitals. long-term educational impacts. generation of amputees, lack of carers for elderly.
38
economic impacts of Eyjafjallajokull volcano
primary: flights cancelled all around Europe. secondary: 200m daily loss for airlines. UK tourism lost 750m. Kenyan farmers and flower producers lost 1.3m a day due to cancelled flights. perishable goods wasted.
39
economic impacts of Haiti earthquake
secondary: $14 billion cost. couldn't rebuild houses as no money or availability.
40
environmental impacts of Eyjafjallajokull volcano
primary: volcanic ash produced temporary global cooling, damaged crops, poisoned animals in nearby farms, people asked to stay inside. flooding. secondary: contaminated water supply for animals- deadly. ash with iron in it caused plankton boom in North Atlantic
41
political impacts of Eyjafjallajokull volcano
secondary: after negative publicity, Iceland launched campaign to encourage tourism
42
preparation for earthquakes
warning and evacuation remote sensing and GIS hazard mapping education building design
43
warning and evacuation
prevent deaths however if done too often, people won't leave
44
remote sensing and GIS
satellites take photos of impacted area- locate damaged areas and map seismic risk. useful for emergency and preparation
45
building design
assess safety of buildings and build new ones steel rods earthquake proof buildings shear walls- multiple panels supported by steel which help a building keep its shape when shaking
46
short-term responses to natural hazards
emergency aid: for relief, rehabilitation and reconstruction. depends on magnitude and impact. NGOs or UN. tailored to needs of disaster. politics can interfere shelter: tents, tarpaulins, blankets supplies: food and water can quickly run out, provided supplies include food, mobile kitchens/ toilets, purification equipment.
47
long-term responses to natural hazards
risk assessment: appraisal or inquest is essential for good emergency operations. focused on what to do if it happens again (warning systems, evacuation plans) education: leaflets, training, schools rebuilding programmes: engineers assess safety of houses and improved ones are built. focus on increased capacity to cope.

geography (4 decks)

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