Physical Geography case studies

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Loma Prieta earthquake

Date and time: 5:04 pm, 17th October 1989 

Magnitude: 6.9 

Location: Loma Prieta, near San Francisco 

Areas affected: Marina district was worst hit. Built on landfill it's soft, sandy soils liquefied, causing buildings and roads to collapse. The Cypress freeway collapsed, causing 42 to 67 earthquake-related deaths.     

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Iceland: Eyjafjallajokull volcano

Date: April 2010 

Location: Eyjafjallajokull, Iceland 

Impacts: due to atmospheric circulation, ash clouds from the volcano affected flights over northern Europe for a week 

  • 100 000 flights were cancelled, affecting 10 million people, losing airline capacity was cut by 30%, European capacity by 75% 
  • Impacts of European flight cancellations were felt in Kenya, where 20% of the economy is based on exporting green vegetables and flowers to Europe, costing US$ 1.3 million daily 
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Montserrat volcano

The island is part of an arc in the Carribean, formed where the Atlantic Plate subducts beneath the Carribean plate. 

On July 1995 the Soufriere Hills volcano began to erupt ash and dust. Eruptions continued for five years. Pyroclastic flow affected much of the island. Very little lava erupted. The volcano is still active. 

Impacts included:

  • Dozens died: two-thirds of its 11 000 people were evacuated, most permanently
  • The capital was destroyed
  • Two-thirds of houses were buried by ash or flattened 
  • Three-quarters of infrastructure was destroyed 
  • The tourist industry collapsed, causing unemployment
  • Farmland and rainforests were destroyed
  • Young people emigrated leaving an ageing population   
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Indian Ocean Tsunami

Date: 26th December 2004

Background 

  • The earthquake causing the tsunami was magnitude 9.0-9.3, it caused one of the world's worst disasters 
  • Upward thrust lifted the floor of the Indian Ocean by about 15 metres 
  • The Proximity of the epicentre to densely populated communities was significant. The earliest waves stuck Banda Ache, Indonesia and were 17 metres high.
  • The low-lying coastlines of neighbouring countries allowed the tsunami to travel inland 
  • The was no early warning system 
  • Coastal mangroves were destroyed to allow tourist development reducing protection

Impacts 

  • 5 million people were affected in 14 countries 
  • Over 230000 people died 
  • Coastal settlements were devastated 70% of people were killed 
  • Infrastructure was destroyed
  • In Sri Lanka more than 60% of the fishing fleet where destroyed 
  • In Thailand, the tourism industry lost US$ 25 million per month and 120 000 people lost their jobs 
  • The total damage exceeded US$ 10 billion 
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Haiti earthquake

Date: 12th January 2010 

Magnitude: 7.0 

  • Haiti is poor with resources spent on reducing poverty not earthquake preparation 
  • High levels of government corruption reduced improvements on infrastructure or living standards 
  • buildings poorly built because of lack of building regulations 
  • Rescue teams found access difficult because of high population density 
  • Few people knew what to do because they had not been prepared for disaster  

Much of the infrastructure was damaged 

  • its ports, main roads and only airport was damaged, preventing aid from arriving increasing death tolls 
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Haiti earthquake response

Haiti's recovery 

  • Haiti was still recovering in 2016
  • 13 million was donated but most was controlled by international NGOs were needed for emergency services 
  • concerns about corruption made unwilling to give money to Haiti's government 
  •  they managed to relieve themselves bringing staff from overseas 
  • Many argue that this reduced Haiti's ability to recover or develop skills within its population 

Progress was slow with 80 000 still temporary housing in 2015 

  • New buildings, roads and schools have been built
  • Health statistics have improved 
  • The government is stronger
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Bangladesh- coastal flooding

Cyclone Sidr swept into Bangladesh from the Bay of Bengal in November 2007, bringing a storm surge up to 6 metres high, heavy rain and strong winds up to 223 km/hr. Coastal districts and offshore islands suffered the most deaths and worst effects 

Why is Bangladesh at risk of flooding? 

Bangladesh is threatened frequently by river and coastal flooding 

  • It is the world's most densely populated country 
  • 46% of the population lives in places less than 10 metres above sea level 
  • It lies on the floodplains of three major rivers which together with smaller rivers empty into the Bay of Bengal through a series of estuaries

Increasing flood risk 

  • Subsidence and removing vegetation - clearing and draining land for cultivation plus building large earth embankments, has caused some estuaries islands to shrink and subside by up to 1.5 metres in the last 50 years, 70% of Bangladesh's mangrove forested coastline has retreated by up to 200 metres and rising sea levels 
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Developed countries coastal flooding

Over the winter of 2013/2014, the UK experienced a succession of major storms one of the worst occurred during 5-6 Dember, bringing a storm surge that affected the east coast of the UK and countries in northern Europe 

The surge was caused by:

  • Intense low-pressure 
  • sea shape and coastline- The North Sea is open to the Atlantic Ocean and tapers southwards in a funnel shape allowing strong northerly winds to push storm surges south. 
  • Sea depth- The North Sea gets shallower and narrower towards the south, increasing the height of tides and storm surges 
  • High seasonal tides  

Impacts of the storm 

  • On the East Frisian coast in Germany and on the Dutch border, the storm surge reached 3.7 metres above sea level 
  • Gusts of over 200km in Scotland 
  • The Thames barrier closed to protect London and the Eastern Scheldt storm surge barrier 
  • 1400 homes flooded 
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The Philippines: a multiple-hazard zone

Hazards include 

  • Volcanoes it has 47 and earthquakes because of the location across the plate boundary on the Ring of Fire 
  • Tsunami- its coast faces the Pacific the world's most tsunami-prone ocean typhoons- it sits within South-East Asia's major typhoon belts. it averages 15 typhoons annually due to its monsoon climate 
  • Steep topography and deforestation make landslides common

Vulnerability 

the combination of rising population, urbanisation and poverty increases the Philippines vulnerability 

  • Economic development had led to rapid urbanisation and high population density 
  • the poor live in coastal areas exposed to the storm surges, flooding and tsunami 

One hazard event can have a knock-on-effect

  • In 2006, an earthquake killed 15, injured 100 and damaged or destroyed 800 buildings 
  • caused a 3 metre-high tsunami
  • Triggered landslides and created a flood  
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