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IB SL Geography > Hazards 3- Case studies > Flashcards

Hazards 3- Case studies Flashcards

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1
Q

What are the different impacts of hazards on developed and developing countries?

A

Developed countries:
-Incur higher damage costs because there are more expensive buildings and infrastructure to be damaged (insurance and repair costs also high).
-Even small costs create problems for the poor.

Developing countries:
-Incur higher death rates because people are more vulnerable, lack awareness of hazards, live in buildings that haven’t been proofed, and don’t have access to communications, decision-making, or emergency services.

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2
Q

Hazard event profile for Haiti and Christchurch earthquakes

A
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3
Q

Characteristics and impacts of tectonic hazards

A

-Spatial predictability: An area that has never had an event will experience greater impacts as people and places will be unprepared

-Areal extent: The larger the area affected by the event, the greater the impacts will be, as more people and places will be affected

-Frequency: An event that occurs often is likely to create cumulative impacts (although rare events will have more energy)

-Magnitude: The greater the magnitude of energy released by an event, the greater the impacts are likely to be

-Speed of onset: The faster the event occurs, the shorter the warning time and the greater the impacts as places are unprepared

-Duration: the longer an event last, the more likely that there will be greater impacts

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4
Q

What are the characteristics of events that present the highest risks?

A

-Have high magnitude and low frequencies

-Have rapid speeds of onset with spatial predictability

-Have a large areal extent

-Tend to occur at subduction zones & collision zones.

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5
Q

The Pressure and Release (PAR) model

A
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6
Q

2010 Haiti Earthquake- tectonics and geography

A

Tectonics = earthquake (conservative boundary)

Geography:

-Epicenter close to capital Port au Prince (25km away), focus shallow (only 13km)

-Spatial extent quite large (120km2)

-Hadn’t experienced an earthquake in 150yrs, so no experience,

-Magnitude 7,

-Speed of onset = sudden ( 30-60 seconds),

-Predictability: none (known fault).

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7
Q

2010 Haiti earthquake secondary hazards

A

-Over 45 aftershocks > 4.5 and two aftershocks of 5.9 and 5.5 within a few days and 5.9 on the 20 January.

-One town experienced a localized tsunami

-Liquefaction in the port area.

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8
Q

2010 Haiti earthquake- living conditions and pressures

A

-Living conditions = Buildings & infrastructure not earthquake-proof, high unemployment, relied on the informal sector, many lived in slums, 72% lived in poverty, homes built on slopes.

-Pressures = rapid rural to urban migration, growth of slums..all put pressure on local authorities. Hillsides stripped of trees to make more space. Low HDI. Education levels are lower, so perception & risk were low.

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9
Q

2010 Haiti earthquake- contribution of poor governance

A

-Basic needs were not being met -limited access to roads, electricity & sanitation.

-Poor planning – deforestation & building on hillsides, no preparedness, didn’t ensure correct building codes, corrupt government.

-Access to health care & education is poor.

-Low-income groups lack a ‘safety net’ after a disaster – personal one ( savings, food) or government one ( social security, aid, free healthcare)

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10
Q

Statistics about Haiti in 2010

A

-One the poorest countries in the world.

-54% abject poverty & 20% GDP from remittances.

-6 months after the event, 98% of the rubble remained uncleared.

-1 in 5 jobs lost.

-80% of schools were destroyed and 25% of civil servants died.

-2017 – 55,000 still in temporary camps.

-2 years after, only 43% of aid was received.

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11
Q

When was the Haiti earthquake?

A

2010

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12
Q

When were the Christchurch, New Zealand, earthquakes?

A

2010 and 2011

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13
Q

Christchurch earthquake tectonics and geography

A

Tectonics = earthquake (conservative boundary)

Geography:
-Epicentre was close to Christchurch (2010- 40km away & 2011 only 10km),

-Shallow focus – only 10km in 2010 and 5km in 2011

-Spatial extent 12km2

-Earthquakes normally occur every 55 yrs

-Magnitude 7.1 & 6.3

-Speed of onset = sudden ( 30-60 seconds),

-Predictability: none ( 100 faults in the area, margin complex/changing).

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14
Q

Christchurch earthquakes- secondary hazards

A

1st large earthquake in 2010, 11,000 aftershocks continued into 2012, 26 aftershocks were 5+ magnitude and x2 +6 magnitude.

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15
Q

Christchurch earthquakes- trigger quake

A

-Led to 6.3 magnitude earthquake on 22 Feb 2011.

-Liquefaction in the city built on the edge of Canterbury plains, which are made of loose river deposits.

-Caused upwelling of 400,000 tonnes of silt.

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16
Q

Christchurch earthquake- seismic lensing

A

-Seismic waves travelled through soft rocks and then bounced back of hard basalt rocks, causing further shaking

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17
Q

Christchurch earthquakes- living conditions and pressures

A

Living conditions

-Those living in Port Hills suffered from large rock fall.

-Many buildings had already been weakened by previous quakes.

-If it wasn’t for the strong building codes, most of the city would have been flattened due to shaking & liquefaction.

Pressures
-Didn’t experience the extra pressures like Haiti.

-Schools had been carrying out regular drills ‘the turtle) since the 2010 earthquake.

-Workplaces & schools had strict emergency plans & emergency services were well prepared.

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18
Q

Christchurch earthquakes- causes

A

-Didn’t suffer from poor governance or from a weak economy or cultural issues.

-NZ is well prepared for earthquakes, but the Greendale fault was unknown until it was revealed after the Darfield 2010 quake.

-The only vulnerability lay in the living conditions, which was due to the 2010 earthquake had already weakened structures. The city didn’t have the time to strengthen & rebuild before the 2011 quake.

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19
Q

Christchurch earthquakes- responses

A

-Temporary housing & portable toilets were supplied, a full emergency plan was in place within 2 hours.

-Vulnerable people were well looked after. Schools amalgamated to ensure provision continued. Farmers helped to remove rubble.

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20
Q

Hazard profile for Haiti 2010 and Christchurch 2011

A
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21
Q

Table comparing the impacts of Haiti and Christchurch earthquakes

A
22
Q

When was the Volcan de Fuego eruption?

A

2018

23
Q

Vulcan de Fuego type of margin

A

Destructive

24
Q

Vulcan de Fuego plate margins diagram

A
25
Q

Need info about destructive margins?

A
26
Q

Composite volcano diagram

A
27
Q

Volcan de Fuego eruption features

A

-Magnitude: VEI 4 – explosive nature, but characteristics of Plinian (eruption column over 10km) & thus severe.

-Speed of onset: Monitored by vulcanologists, but the build-up of energy caught scientists by surprise. An evacuation warning was given 8 hours in advance.

-Duration: Major explosions lasted 16 hours. Small eruptions almost every 20 days & has been very active since 2002.

-Areal extent: Ash spread over a 19 km radius. Pyroclastic flow spread 10 km

-Spatial predictability: Predictable – Pacific Ring of Fire & know the location.

-Frequency: Erupting every 20 days ( small), erupted 60 times since 1524. Last major eruptions 1932, 1974 & 2012.

28
Q

Typical volcano hazard profile

A
29
Q

When was the volcanic eruption in Kilauea, Hawaii?

A
30
Q

Diagram of shield volcano

A
31
Q

Diagram of Hawaiian hotspot

A
32
Q

Need info about hotspots?

A
33
Q

Kilauea eruption features

A

-Magnitude : 0 on the VEI – Hawaiian eruption, non-explosive

-Speed of onset: Quite slow & the fastest lava is only moving at around 17mph ( slightly faster than a running man). Generally can walk away from the lava.

-Duration: Long, been active since 1983 and the last eruption similar to the current one was in 1955, where it lasted 88 days.

-Areal extent: Covers 9.4 square miles (June 18)

-Spatial predictability: Predictable – we know where the mantle plume is.

-Frequency: Very frequent, been erupting for 35 years & currently has been spewing lava for over 3 months (Aug 2018)

34
Q

Volcan de Fuego- vulnerability

A

-Living conditions = 60% lived in poverty and poverty had been rising before the eruption, GDP $8,200. The area around the volcano –rural – rely on agriculture. Little training as to what to do if the volcano erupts.

-Pressures = Low HDI. Education levels are lower, so the perception of risk was low. Residents will have been attracted to the area due to fertile soils.

-Causes = Poor governance –The government told people to evacuate people 7 hours before the eruption, but they did not act. Education was poor, people were not prepared. Low-income groups lacked a ‘safety net’ after the disaster, as did the government - debt 30% of GDP. Allowed villages to develop in the foothills of a violent volcano. Only one seismometer monitoring the volcano.

-High corruption rates.

35
Q

Table constrasting the geographic factors affecting the impacts of Volcan de Fuego and Kilauea

A
36
Q

Table contrasting the impacts of Volcan de Fuego and Kilauea

A
37
Q

Kilauea- vulnerability

A

-Living conditions = Buildings & infrastructure are earthquake-proof, wealthy nation.
Many islanders don’t have volcano insurance.
Tourist numbers fell with the island losing $5mn May – June.

-Good governance – Residents well versed in the risks of living close to an active volcano. Scientists monitor the rift zones 24 hours a day. Evacuation orders were issued early. Residents were encouraged to create their own emergency action plan & have somewhere to stay when lava flows near their residency.

-Evacuation plan was put in place immediately and an emergency disaster centre was set up to support residents.

-Those who lost homes entitled to $34,000 in federal aid.

38
Q

When was the Mocoa Landslide?

A

2017

39
Q

Table showing the features of the Mocoa landslide

A
40
Q

Typical landslide hazard profile

A
41
Q

Typical volcano hazard profile

A
42
Q

Hazard profile for Macoa landslide (blue) and Porthills rockfall (green)

A
43
Q

When was the Port Hills (Christ Church) rockfall?

A

2011

44
Q

Features of Port Hills rockfall

A

-Timing: 22 Feb 2011, 12:51

-Magnitude: Rockfall - Highly destructive

-Speed of onset: Very quick

-Duration: very short, triggered by the earthquake.

-Area affected: Port Hills suburb (scattered over an area 65km squared) by 6,000 boulders.
170 landslides over 150 km squares.

-Frequency: Last one was 7,000 years ago, so not all earthquake events have triggered them.

-Predictability: Risks still high today – future earthquakes, rainfall….. 400 homes were initially deemed unhabitable due to future rockfall risk.

-Proximity: Only 7km from epicenter ( suburbs of Christchurch)

-Deaths: 5 dead

45
Q

Impact of the Port Hills rockfall

A
46
Q

Impact of Mocoa landslide

A
47
Q

here is Port Hills?

A

New Zealand (suburb of Christchurch)

48
Q

Where is Mocoa?

A

Putomayo, Colombia

49
Q

Vulnerability factors affecting the Port Hills rockfall

A

Physical Factors:

-Unstable geology due to tectonic processes.

-Homes built on steep slopes

Dynamic factors:

The -2010 earthquake would probably have loosened rocks.

Root causes:

-Should residents be allowed to build on steep slopes in an earthquake-prone area?

-It had been identified for potential landslides & rockfalls in 1977 by the Environmental Agency & then by Engineering Lifelines in 1997.

50
Q

Vulnerability factors affecting the Mocoa landslide

A

IB SL Geography (20 decks)

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