volcanic hazards Flashcards
what is an active volcano
a volcano that erupted in the last 10,000 years
eg: Mount Etna, Italy
what is a dormant volcano
a volcano that hasn’t erupted in 10,000 years but is expected to erupt again
eg: Mount Fuji, Japan
what is an extinct volcano
a volcano that isn’t expected to erupt again
eg: Castle Rock Edinburgh, Scotland
characteristics of volcanoes at constructive margins
- usually shield volcanoes
- produce basaltic lava: dark lave hot (1000 degrees celcius), low viscosity
- frequent weak eruptions
- wide sloped volcano/shield volcanoes
- low gas content
- underwater margins: magma rises to fill spaces left by plates to form ocean ridges
- land margins: form rift valleys that thin out and allow lava to pass through
characteristics of volcanoes at destructive margins
- usually composite volcanoes
- produce andesitic and rhyolitic lava : cooler with higher viscosity
- infrequent violent eruptions
- steep volcanoes
- high gas content
name 6 volcano hazards
- pyroclastic flows: mix of super heated gas, ash and volcanic rock that travel far (10km-15km) at high speeds(80 km/h) and destroy everything in their path
temperature: 800 degrees Celsius Pompeii - lava flows: speed depends on volcano slope and lava viscosity. typically lava flows are slow but destroy anything in their path
- volcanic gases: carbon dioxide/sulphur dioxide released by lava that make it difficult to breathe
- tephra(pyroclastic and ash fall out): material that is ejected from the volcano and falls to the ground. ranges in size that can damage/kill or make it hard to breathe
lahars(mudflows): occur when tephra mixes with large bodies of water - 1985 Amero Tragedy
acid rain: volcanic gases react with water vapour which damages ecosystems
acidity of 4
how is the magnitude of volcanic hazards measured
measured using the Volcanic Explosivity Index which grades volcanoes on a scale of 0-8 based on the amount and height of material ejected.
-Eyjafjallajokull was a 3
-Mnt St Helens was a 5
Hawain volcanoes are 1
-Yellow Stone was 10
what is the importance of the frequency of volcanic events
typically volcanoes with less frequent volcanic eruptions are larger in magnitude
randomness vs regularity of volcanic events
some volcanoes will erupt at regular intervals while others may be dormant for a long time and then erupt several times
estimated that 50 to 60 volcanoes erupt per year
predictability of volcanic events
- shape, ground deformation monitored with lasers and tiltmeters
- small earthquakes show movement in magma
- Sulphur in the air can be measured with gas spectrometers
short term responses
occur immediately after the event like
evacuations and emergency supplies
volcano case study :
location
date
plate margin
volcano type
- Iceland Eyjafjallajökull
- 20th March 2010
- constructive north American and Eurasian plate
- composite volcano
4 economic impacts of the Eyjafjallajökull volcano eruptions
- airlines lost £130 million per day
- European tourism lost between £5-£6 million
- £80 million loss for Iceland
- Nissan halted production as parts couldn’t be imported from Iceland- globalization/TNC
3 social impacts of the Eyjafjallajökull volcano eruptions
- 0 deaths: volcano erupted 75 miles from capitol
- people had to wear goggles and masks due to the thickness of ash
- flights were delayed and cancelled
4 environmental impacts of the Eyjafjallajökull volcano eruptions
- temperature rises killed fish
- lava and ash rich soils are good for agricultural use
- eruption caused ice on volcano to melt which caused floods in southern Iceland on the 14th of April
- plankton bloom triggered by dissolved iron deposited by volcano
5 immediate responses to the Eyjafjallajökull volcano
- 500 cattle farmers were evacuated
- roads shut down
- flights cancelled
- local population was evacuated for safety and because of respiratory threats due to the ash
- authorities to order 700 people to evacuate due to flooding in the south
5 long term responses to the Eyjafjallajökull volcano
- jewellery created from ash to sell to tourists
- roads reconstructed
- volcano made into a tourist attraction
- rocks from volcano used for construction
- residents clean up ash
how was Iceland vulnerable to the Eyjafjallajökull volcano - 3
- vulnerable to ash clouds is higher due to the extent of the eruptions
- Iceland has a team of scientists and meteorologists dedicated to researching and monitoring volcanic activity at the Icelandic Met Office
- between the 3rd and 5th of May they received multiple warnings about the earthquake
what 4 hazards occurred as a result of the Eyjafjallajökull volcano
- on the 20th of March an eruption of lava
- on the 14th of April flooding
- an estimate 140 million cubic meters of ash released
- interaction of water and magma created 10km lava plumes of fine ash and gas
- this was carried south easterly to winds Norway, the Faroe Islands and Northern Scotland
volcano management: prevention
- volcanoes cannot be prevented
- the risks of volcanoes can be prevented by keeping people away from volcanic hazards
- e.g. preventing building around volcanoes
volcano management: preparedness - 4
- monitoring allows you to notice volcanic eruptions so warnings can be given out
- educating those who lives around volcanoes on the risk so people know what to do if there is an eruption
- planning evacuation procedures
- training response teams
volcano management: mitigation - 4
- direct intervention to the volcano: e.g. concrete blocks to steer lava away from areas at risk
- strengthening buildings at risk of mudflows or ash pileup
- evacuation and exclusion zones
- mitigating effects on health by having emergency aid and rescue
volcano management: adaption - 3
- move away from areas at risk
- capitalize on opportunities like encouraging tourism
- change profession so you are less likely to be affected by volcanic hazards
