Geography case studies (volcanos, earthquakes and hurricanes)

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  • Created on: 26-05-13 13:34

Gujarat earthquake, India 26th January 2001 (event

  • Location: Near small town of Bhuj in Gukarat, India.
  • Focus: 17km below surface
  • Strength: 7.9 on the Richter scale
  • Death toll: 20,000 (up to 30,000) authorities unable to cope with magnitude of disaster (collapose of district administration and complete communicaiton breakdown with outside world.)
  • Injuries: over 160,000
  • Homeless: more than 1 million
  • Destroyed buildings: 345,000 dwellings (blocks of flats to simple mud-built houses_
  • Structural damage:more than 800,000
  • All four hospitals in Bhuj destroyed. (Difficult to deal with injured survivors)
  • Cultural heritage destroyed (Forts, palaces, temples and monuments, many centuries old; Pragmahal Palace partly destroyed.)
  • Communities severely disrupted and power lines brough down
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Gujarat earthquake, (aftermath)

  • Several hundred aftershocks in days following (most small but one over 5 on Richter scale) Caused more damaged to already weakened buildings.
  • Widespread looting of damaged properties.
  • International rescute teams: Britain sent 69 strong team sponsorted by Department for International Development.
  • Water purification tablets issued.
  • Dissinfectant sprayed on collapsed buildings (prevent spread of disease by rotting bodies)
  • Indian government sent 5,000 troops into area with 40 military aircraft nad three navel vessels two were floating hospitals capable of treating more than 200 patients.
  • Military transported medical aid, food, tents and communicaiton equipment by air to worse affected areas.
  • Authorities feared epidemcs of typhoid but quick action meant didn't occur. However evidence of widepsread diarrhoea and gastroenteritis.
  • Loss of 20,000 cattle.
  • Overall cost: $4-5 billion 
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Market Rasen earthquake, Lincolnshire 27 feb 2008

  • Location: 12:56 AM, Market Rasen, Lincolnshire, UK.
  • Focus: 18.6 KM below surface.
  • Strength: 5.2 on Richter scale.
  • Epicentre: 4KM north of Market Rasen.
  • Afterscocks: Largest 2.2 on RIchter scale.

British Isles isn't near plate boundary so major earthquakes unknown.

  • Homes were shaken, causing panic and calls to emergency sevices.
  • Chimeny stacks collapsed, falling onto streets below.
  • One serious injury of chimeny falling onto a sleeping man in barnsley breaking his pelvis.
  • House roofs were damaged as tiles fell off.
  • Secondary daamaged to roads and pavements from falling masonry.
  • Total cost to isurance companies: Estimated £30 million
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Northridge earthquake, Los Angeles, 17th Jan 1994

SInce 1993 five major earthquakes in Los Angeles measuring at least 5.8 on Richter scale.

  • 1993 Long Beach, 6.4 Richter scale, 120 people died.
  • 1971 San Fernando, 6.6 Richter scale, 65 people died.
  • 1987 Whittier Narrows, 5.9 Richter scale, 8 people died.
  • 1991 Sierra Madre, 5.8 Richter scale, 2 people died.
  • 1997 Northridge 6.7 Richter scale, 57 people died.

Northridge earthquake

  • 4.30 AM on Monday 17th January 1994.
  • Movement along a previosuly unknown thrust fault.
  • Focus: 18.4 KM below surface.
  • Ground acceleration highest ever instrumentally recored in a North American earthquake
  • Early morning time resulted in lower death toll, less people on roads. Federal holiday (Marin Luther King Day)
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Northridge earthquake (aftermath)

  • 57 people dead
  • More than 1,500 serious injuries (over 10,000 minor)
  • 12,500 buildings suffered moderate to serious damage.
  • 11 major roads seriously damaged. (up to 32km from epicentre)
  • More than 11,000 landslides triggered some blockiong roads and damaging water lines.
  • Landslides damaged homes, particually in Pacific Palisades area.
  • More than 20,000 people imdediately made homeless.
  • 11 hospitals suffered structural damage and unable to serve local neighbourhoods.
  • 600 afterschocks (Largest magnutude 5.6 11 hours after main event.)
  • Several days after event 9,000 premises with no electricity, 20,000 no gas suply and 48,500 had little or no water supply
  • Estimated cost of the damage exceeded $30 billon and more than 700,000 aplications made to federal and state assistance programs for financial help.
  • Event lead to :egislation decreeing all hospitals in California should by 2005 have earthquake proof acute care units and emergency rooms.
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Indian Ocean tsunami, 26th December 2004

  • Pressure built where Indo-Australian plate subducts under the Euroasian plate south of Myanmar (Burma)
  • Slippage of plate 25km beneath Indian Ocean., sea bed rose on Euroasian plate rose several meters. generating 9.0 magnitude earthquake.
  • Epicentre: Off northwestern tip of Sumatra.
  • Tsunami devastated several islands e.g. Maldives and coastlines of countries bordering ocean e.g Indoneasia and Malaysia
  • Tsunami wall more than 25 meters in height. 
  • Warning systems existed in Pacific basin but none in Indian Ocean.

Effects of tsunami

  • Dead: 300,000
  • Tens of thousands injured by force of wave and debris/
  • Coastal areas in Thailand, and Maldives tourist destinations many hundreds dead or missing from Europe.
  • More than 1,500 villages destroyed in Northern Sumatra. 
  • Millions of people made homeless.
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Indian Ocean tsunami, aftermath (cont)

  • Massive damage to tourist infrastructure (hotels, bars, restaurants and shops)
  • Massive damage to bridges and railway lines in Coastal areas. (Sri Lanka, train swept off tracks resulting in more than 1,000 deaths)
  • Coastal areas suffered economic damage, particularly agriculture and fishing. for many years.
  • Hospitals and clinics washed away or damaged, large amount of medical aid required from outside affected areas.
  • Economic damage estimated less than $5 billion by insurance companies.

Western side of Indian ocean countries received warning.

  • Kenya reacted quickly moving thousands of tourists off beaches to safety.
  • Event also meant that warning systems have been set up amount countries that boarder the Indian Ocean.
  • Little use to countries close to epicentre e.g Sumatra but beneficial for others.
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Mt Nyiragongo, Congo 2002 volcano

Lies in Virunga Mountains in the DRC, associated with Africvan rift valley.

  • Main crater 250m deep, 2km wide and often contains a lava lake.
  • Erupted more than 30 timse since nineteenth century.
  • With it's neighbouring volcano Nyamuragira responsible for 40% of Africa's recored volcanic eruptions.
  • Lava basaltic in nature and very fluid, can flow downhill greater than 90km per hour.

Jan 2002 eruption was unexpected

  • Warnings enabled most people to flee from effects.
  • Large eruption, opening a fisure 13km long on southern flank and spewuing lava up to 2m  deep which floswed in the direction of Goma and Lake Kivu.

Effects:

  • Third of Goma destroyed. Town populatin 200,000
  • Commerical centre of town, water and power supplies and medical facilities destroyed. Three health centres and one hospital.
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Mt Nyiragongo aftermath (Cont)

  • Lava covered northern third of runway at Goma airport
  • Death toll: 147 people
  • More than 350,000 people fled the area, Particularly to Gisenyi, Rwanda, causing problems providing food and shelter.
  • Lake Kivu polluted by sulphurous lava, major drinking water source in area.
  • Fear of release of toxic gases from Lake Kivu due to temperature increase.
  • Structural damage by several earthquakes accompanied by eruption (largest magnitude 5)
  • Thousands required medical attention, first for effects of smoke and fumes from lava which caused eye irritation and respiratory problems.
  • Then for diseases such as dysentery linked to drinking contaminated water.
  • Looting from abandoned homes, many killed when petrol store exploded (looters)
  • Red alert issued for Goma and surrounding area. Enabling full evacuation so low death rate.
  • Two days after eruption UN bran humanitarian aid.
    Emergency rations initially high energy food e.g biscuits
    followed by substantial food aid. e.g. maize, beans and cooking oil. 
  • UN cost: temporary shelter, clean water, food, blankets ECT for refugees at $15 million.
  • Higher cost for rebuilding Goma's infrastructure. homes and livelihoods. 
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Mt Etna 1991-1993 Sicily volcano

Height: 3,323 meters.
Location:
Near Catania, Sicily's second largest city. 
Volcano type: Stratovolcano
Lava flowed from vents high on eastern flank in Valle del Bove advancing on settlement of Zafferana. 

Protective measures introduced to halt//slow the speed of lava flow.

  • Construction of large earth barrier across Val Calanna at southern end of Valle del Bove.
    21 meters high, and more than 400 meters long.
    Held back lava for several months.
  • Spring 1992, lava began to spill over barrier towards Zafferana. 
    Smaller barriers erected across valley rapidly overwhelmed.
    Lava destroyed orchards and few small buildings.
  • attempted block of flow by blocking primary feeder channel by dropping concrete blocks from helicopters through roof of upper lava tube.
  • May 1992: Engineers blasted openings into lava tube. encouraged new direction of flow. Lava stopped advance on Zafferana and eruption ended 10 months later (early 1993)
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Mt Etna 1991-1993 Sicily (aftermath)

Most successful attempt at changing the course of a volcanic eruption.
However Zafferana may never have been in danger.
Mt Etna record for longest eruptions. 

Success of schemes based upon:

  • Low effusion rates during eruption.
  • High elevation of eruptive vents (between 2,200-2,350 meters in altitude. lava had to flow more than 8km before becoming a serious threat.
  • Lava was able to be diverted into uninhabited areas (at least 7km from nearest village.)

More serious eruption occurred in 2002 lava completely destroyed Piano Provenzana ski station, and damaged part of another station.
Clouds of ash affected area, particularly city of Catania

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Soufriere Hills, Montserrat 1995-1997 volcano

July 1995 dormant for several centuries.  

Eearly activities: ash and steam explosions rising more than 2,500, several earthquakes.
Volcano became quiet for a period of time

March 1996 produced a huge ash cloud accompanied by dome growth and small pyroclastic flows.
Early1997: Continued down growth, small explosions and ballistic projectiles.

Event climaxed 25th June large explosions resulted in extensive pyroclastic flows from 4-5 million meters cubed of material.
Most flowed down northern flank, damaging houses killing some inhabitants.
Only 40/100km2 considered safe to live on.
Capital Plymouth buried in over 10m  of ash and mud, airport and docking facilities destroyed and southern part of island rendered uninhabitable.

Volcano remained relatively quiet since 1997 

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Soufriere Hills, Montserrat 1995-1997 (aftermath)

Montserrat still dependent territory, British government provided relief by:

  • Setting up exclusion zone 
  • evacuation of 7,000/11,000 inhabitants to neighbour islands, (Antigua or resettlement in uk.)
  • Resettlement of population from south to the safer north of island.
  • setting up temporary shelters in north.
  • Re-establish,ment of air and sea links with the island.
  • Building new permanent housing
  • Moving capital from Plymouth to Salem.
  • Setting up Montserrat Volcano Observatory (MVO) to monitor Soufriere hills activity.

UK government spent more than £100 million in assisting migration and restoring services.
Including:

  • Restoring agricultural and employment on the island.
  • restoration of tourist industry.
  • return of refugees from UK and elsewhere.
  • construction of new airport Gerald's (Cost £11 million opened in 2005

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