1.1 Case studies Flashcards
1
Q
Indian Ocean Tsunami 2004 - description
A
- 26th December 2004
- hypocentre 160km away from Sumatra, Indonesia
- first waves arrived 20mins after quake
- 800km/h waves
2
Q
Indian Ocean Tsunami 2004 - causes
A
under sea 9.2 magnitude earthquake caused by subduction of Indian plate under Burma plate
3
Q
Indian Ocean Tsunami 2004 - Social Impacts
A
- No tsunami warning system in place
- 300,000 deaths
- 1.7 million left homeless
- Wide spread of disease (cholera and dysentery) through mixing sea water with sewage
- 6 million people requiring emergency aid
4
Q
Indian Ocean Tsunami 2004 - economic impacts
A
- loss of earnings from tourism
- fishing industry damaged through destruction of ports, boats, equipment
- destruction of crops and farmland by seawater
- transport links damaged
5
Q
Indian Ocean Tsunami 2004 - environmental impacts
A
- mangrove forests damaged
- 8 million litres of oil leaked from oil plants in Indonesia
- coral reefs damaged/destroyed
6
Q
describe the Nepal Earthquake
A
- 25 April 2015
- 7.9 on Richter scale
- depth of 8.2km
- Destructive plate margin
- Indo-Australian plate colliding with Eurasian Plate
- interplate
7
Q
Nepal Earthquake - secondary impacts
A
- Landslides and avalanches which blocked roads and hampered relief efforts
- Avalanche on Mt Everest killed 19 people
- Avalanche in the Langtang reagion left 250 missing
- Landslide blocked River Kaii Gandaki - which caused flooding in capital
- 9000 deaths
- 22,000 injuries
- $10bn in damages
8
Q
describe the Gujurat earthquake
A
- 2001
- intraplate
- 7.7 magnitude
- in northern India
- along a rift fault associated with India + Eurasian plate boundary
9
Q
Impacts of Gujurat earthquake
A
- 13-20,000 deaths
- 167,000 injured
- 340,000 buildings destroyed
10
Q
Eyjafjallajokull 2010 - description
A
- stratovolcano - explosive eruptions associated with the mid-atlantic ridge
- prior to eruption, 5000 smaller earthquakes recorded near to the volcano’s crater, located beneath a glacier
- 14th April 2010, erupted from main crater in rthe middle of the glacier
11
Q
Primary impacts of Eyjafjallajokull eruption
A
- 150m ice cap melted causing flooding
- 800 people evacuated
- 20 farms destroyed
- schools and businesses closed
- damage to crops and livestock
12
Q
Secondary impacts of Eyjafjallajokull eruption
A
- jokulhaup flooding damaged homes
- costs of repairing flood defences
- long-term increased tourism and businesses - 1.7million tourists came as a result
- Roads bulldozed to allow flood water to reach sea
- European travel industry had £1.7bn losses
- 6 flightless days
- London lost £102mn of tourist income
13
Q
Describe the Mt. St. Helens eruption.
A
- located in Washington state
- deadliest volcanic event in US history
- along subduction zone of Juan de Fuca and North American plates
- plinian eruption
- VEI = 5
- volcano continuously active until 2008
14
Q
Mt. St. Helens’ 1980 eruption
- What were the precursor events leading up to the eruption that alerted geologists?
A
- small earthquakes in March 1980
- frequency of high magnitude earthquakes increased to about 8 per day
- phreatic eruptions (steam eruptions)
- formation of new crater at summit of volcano
- surface deformation due to accumulation of magma at shallow depths
15
Q
Mt. St. Helens’ 1980 eruption
- What caused the May 18th lateral blast?
A
- 5.1 magnitude earthquake directly beneath volcano and northern slope collapsed, causing large debris avalanche
- sudden pressure change led to expansion of volcanic gases in the underlying magma
- culminated in a northward-directed lateral blast
16
Q
Mt. St. Helens 1980 eruption - secondary impacts
A
- 600km^2 of surrounding forest destroyed
- 57 deaths
- 200 homes destroyed
- volcanic ash deposited across Washington, Idaho, and Montana
17
Q
Mt. St. Helens 1980 eruption - how has the eruption changed volcanic monitoring in the area?
A
- network of seismometers and GPS stations set up
- data collected during and after eruption provided a baseline for other studies
- enabled scientists to observe reawakening of a volcano with modern monitoring techniques
18
Q
Describe the 2022 Tonga earthquake
A
- occurred on uninhabited island within Tongan archipelago in south pacific
- part of volcanic arc along subduction zone extending from New Zealand to Fiji
- most powerful point of eruption occurred on Jan 15, sending an ash plume over 20km into the atmosphere
- VEI = 4
- 0.5km^3 released
19
Q
Impacts of the 2022 Tonga earthquake
A
- caused tsunami waves reaching as far as Japan (at least 3 people killed in Peru)
- Tonga is a developing nation (104th on 2020 HDI ranking)
- estimated US$90m in damages (18.5% of Tonga’s GDP)
- damaged 600 buildings
- crops lost, fisheries damaged
- internet coverage not restored until 5 weeks after eruption
20
Q
Describe the Pacific Tsunami Warning System
A
- 46 member states
- over 90% of tsunami casualties occur in area
- aims to increase community resilience
- uses seismic data from IRIS
- uses DART system - ocean bottom pressure recorders that measure changes in sea surface height
21
Q
Advantages of Pacific Tsunami Warning System
A
- Advanced warning saves lives
- identify long-term patterns and areas at risk
- centralised data is available for researchers and aid providers
22
Q
Disadvantages of Pacific Tsunami Warning System
A
- not much notice
- expensive so out of reach for LICs
- require mobile devices
23
Q
Describe the Haiti earthquake
A
- 2010
- magnitude 7
- conservative plate boundary between North American and Caribbean plates
- shallow focus: 5 miles deep
24
Q
Impacts of Haiti Earthquake 2010 (5)
A
- 316,000 deaths
- 280,000 buildings destroyed
- 1.3 million left homeless
- hospitals and schools damaged
- airport control tower destroyed, preventing aid from landing
25
Q
Long-term impacts of Haiti earthquake
A
- only 48% of $13.34bn donations reached Haiti as a lot of money west to NGOs not in Haiti so overheads had to be paid
- cholera outbreak caused by waste from UN peacekeeper base leaking into local river caused 10,000 deaths
- many still homeless, access to services is poor
- by 2013, 279,000 people lived in ‘tent cities’
26
Q
Haiti earthquake - why were the impacts so severe?
A
- no building regulations so buildings were poor quality and unable to withstand earthquake
- part of presidential palace collapsed, trapping government officials inside and leading to delays in organising relief efforts
- morgues quickly overwhelmed so bodies buried in mass graves or left in the open
- language barriers, purchase of overpriced supplies, and staffing changes meant NGOs were slow to provide housing
27
Q
Describe the 2011 Tohoku Earthquake
A
- 9.0 magnitude
- epicentre 43 miles east of Tohoku, Japan
- 20mile deep focus
- destructive plate margin: subduction of pacific plate under Eurasian plate
- friction build-up led to ‘megathrust’ quake
28
Q
Tohoku Earthquake - short-term impacts
A
- over 20,000 deaths
- 332,395 buildings destroyed, leaving 130,927 homeless
- 800 aftershocks
- tsunami reaching 40m high, completely overtopping existing 12m-high tsunami defences that cost billions to build
- despite tsunami warning system, only 58% of coastal residents responded to warnings and headed to higher ground
- total energy released was 600m times that of Hiroshima bomb and shifter Earth’s axis
29
Q
Tohoku Earthquake - Long-term impacts
A
- tsunami flooded nuclear power stations and led to meltdown of 7 reactors, including Fukushima
- economic costs of $235bn, most expensive disaster in history
- Three reactors overheated, melted and released radioactivity into the air during explosions, and also into groundwater which eventually reached the Pacific Ocean
