Volcanic Eruptions

Why Is There A Volcano Here?

• Volcano on the island of Montserrat, in the Caribbean sea
• On the Antilles volcanic arc, it is above the subducting North American plate
  • The sediments and water in the crust mean it has a lower density when it melts so it rises to the base of the crust and creates a volcano.

Background Information

• Previously the island occupied 11,000 people.
• The volcano had lain dormant for 400 years previous to th eruption.

The Eruption

• Earthquake swarms detected
• Pyroclastic flows covered the Tar River valley and created a new delat when they reached the sea.
  • (Pyroclastic flow also destroyed Plymouth (capital city) SW of island and Bramble airport.)
  • Lahars slowly covering Plymouth

Responses

• Plymouth abandoned in 1996
• Exclusion zone expanded in 1997 and residents advised to wear helmets and masks outdoors
• Residents told to move north, 5000 now in shelters,  August 1997
• In 1997, th eBritish Government offered £2400 to each adult to help with relocation
• Development of Little Bay Port to replace Plymouths facilities
• Conversion of St Johns Hospital to main island hospital
• Improving air access

Impacts Of The Eruption

• 2/3 of the islanders have left the island, 8000 people
• Collapse of the tourist and rice industry
• Unemployment has risen from 7% to 50%
• Respiratory problems caused by the ash
• Skill shortage due to the number of people that left the island
• 70% rise in rent for accomodation
• 19 died in total
• Pyroclastic flows incinerate organic material as well ash covering them

Why Is There A Volcano Here?

• Positioned on the Great African Rift Valley where plates are diverging from eachother
• The eruption was caused by a shift in the plates opening up a 3km fissure on th esouthern flank of the volcano

Background Information

• The volcano is north of the city of Goma in the East of the Democratic Republic of Congo
  • Very far from the capital Kinshasa
  • On the border of Rwanda and Uganda
  • Population of Goma is 1 million
• Equipment stolen from observatories by rebels, meant scientists weren't observing the volcano

The Eruption - January 2002

• A 13km fissure opened up which poured out lava flowing at an incredible 60mph
• Earthquake accompanying the eruption was 5 on the Richter Scale
• 7000 tonnes of sulphur dioxide emitted each day by the volcano

Responses

• Religious beliefs meant people were reluctant to leave, believing they wouldnt be punished
• Mixed messages were given, people told to stay and leave by different people.
• Half a million people left Goma, lots settled in the jungle in Rwanda
• Within a week, most people had had to return to Goma to collect aid
• Oxfam tried to deliver 15 litres of clean water to each person
• An armed guard now travels with the vulcanologists to protect them from the rebels
• Children are educated to prepare them for future eruptions

Impacts

• The airport was cut in two by lava flows
• Lava cooled leaving rock as much as 3 metres deep
• The ground became more fertile due to the new layers of ash
• 147 people died in the eruption
• 1/3 of Goma was destroyed by the lava flows

Why Is There A Volcano Here?

• Iceland lies on a divergent plate boundary

Background Information

• There are peaks in Icelandic volcanic activity every so often, currently experiencing one
  • Katla volcano in Iceland, much bigger than E15 and predicted to erupt soon
    • 10km wide caldera, 750m of ice on top
• The lava was very basaltic menaing the eruption was explosive
• Icelandic people are very aware of the imminence of future eruptions and aren't afraid because they know how to deal with them (synopticity)

The Eruption

• The glacier on top of the volcano meant the ruption was a lot worse
  • The way the melted water mixed with the lava and created huge amounts of ash
• A fissure opened up, 150m in length, launching 1000 degree C lava up to 150m in the air
• A normal supply of lava lasts for a couple of days, although magma left from an eruption in 1821 meant there was months supply of lava.

Reponses

• 500 farmers were evacuated overnight.
• Airports in northern and western Europe were shut down for 6 days, costing £1.2bn.
  • Impacted apporximately 10 million travellers
• Icelandic people are preparing for future eruptions that will be even bigger
• Local people were advised to use ags masks and helmets

Impacts

• Kenyan flower industry was impacted costing producers between £1.5m and £2m a day.
  • (Planes weren't able to fly out the flowers to Europe)
• A thick layer of ash fell on nearby pastures of Raufarfell, 5cm fell
  • This became wet and thick and made it difficult to farm
• River levels rose as part of the ice cap melted, this disrupted roads and damaged bridges
• Local people living close, are suffering from respiratory issues
• New born lambs killed due to ash in their lungs

Why Is There A Volcano There?

• Japan has approx. 108 active volcanoes
• It is on the main southern island, Kyushu in Japan, on an island arc
• It is between the Phillipine, Eurasian and Pacific plates on a convergent plate boundary

Background Information

• Mount Aso is a popular tourist destiation
• Not many people living near to the volcano
• In 1953, 6 tourists were killed in an eruption

The Eruption

• An ash cloud was sent up 2000 metres
• There was no warning of the eruption
• Parts of the ash cloud collapsed into several pyroclastic flows

Responses

• People were banned from going near the site, 30 people evacuated
• Cancelled at least 24 flights from Kumamoto airport
• A 4km wide area was closed around the crater
• Danger level increased to 3 out of 5
• There was an immediate eruption warning once people knew it was erupting

Impacts

• Ash fell as far as 4km away from the crater
• No reports of injuries