Volcanic Hazards Flashcards
What are some characteristics of volcanic eruptions at constructive
margins?
They are Basaltic lava eruptions with low viscosity (meaning it’s runny), the eruptions are frequent but rarely violent.
What are some characteristics of volcanic eruptions at Destructive margins?
They are Andesitic lava eruptions with high viscosity, so they flow less easy but can also cause blockages resulting in more violent but less frequent eruptions.
Name 6 volcanic hazards
PYROCLASTIC FLOWS/ Nuee ardentes
+ A mixture of super-heated gas, ash and volcanic rocks that travel at high speeds down the side of a volcano, they can flow long distances and occur with little warning. Can cause tsunamis too.
LAVA FLOWS
+ These flows will destroy anything in their path and the speed depends upon the viscosity.
VOLCANIC GASES
+ Gases such as Sulphur dioxide released by volcanoes can be harmful to humans and animals.
ASH FALLOUT
+ The ash and rocks are naturally sorted by gravity with the heaviest ones falling neatest to the volcano, these can destroy buildings and kill people, finer ash can stay suspended longer and travel many miles, suffocating plants and grounding transport.
LAHARS
+ Mudflows are when volcanic material (TEPHRA) mixes with water from snow melt or rainfall, they can flow very quickly and bury and flood natural habitats and human settlements.
ACID RAIN
+ Volcanic gases can react with water vapour in the atmosphere and create acid rain that can damage ecosystems and deteriorate buildings and infrastructure.
When was the Ejyjafjallajokull volcanic eruption?
Initially erupting on the 20th of March, it continued throughout March and April 2010.
What caused the Eruption?
The volcano sits on the Mid-Atlantic ridge where the constructive plate margin of the Eurasian and the North American plate are diverging.
What were some of the primary impacts?
> The melting of the glaciers that sat atop the volcano caused huge issues with flooding. Much of what limited fertile soils Iceland had were washed away and animals suffocated in ash and pyroclastic fallout of up to 2 meters.
> Parts of the ring road were washed away alongside power cables and other infrastructure.
> Residents in some areas were told to stay indoors for up to 7 days to prevent ash induced breathing difficulties.
> 0 people died
> Ash rose 11,000 meters into the air and grounded 13,000 flights across Europe, in the crucially busy Easter holidays.
Secondary impacts included:
> Food prices soared by up to 30% because of crop destruction in Iceland and distribution issues.
> Farmers in Kenya were affected as they couldn’t export their produce.
> There was a severe worker shortage in the U.K, most notably with teachers as they couldn’t return to work after they were stranded abroad.
Responses included:
> Largely involved mitigation.
> Iceland invested in lava channels to divert lava away from the newly fertilised farmland. Yields increased by up to 30%.
> Research was carried out into planes that could fly in ash to minimise disruption in future events.
> Many European companies, most notably Tesco’s began to diversify their supply chain so that similar events in the future would have less impact.
> The event helped to boost Iceland’s tourist industry, witnessing a 240% growth in tourists over 5 years after the eruption.
