Flashcards in Volcanic Hazards Deck (16)
Describe the distribution of volcanoes
95% at plate boundaries
Large amounts around the Pacific ring of fire e.g. Between pacific and Eurasian plates, some found along the mid Atlantic ridge. And east asian belt. some at hotspots
Give five types of volcanic hazard
Nuee ardente - super heated gases and volcanic rock, high speed up to 80Km/h
Lava flows - slower but different viscosity varies speed. Causes secondary impact of fires
Volcanic gases - CO2 and SO2 both released into atmosphere leading to acid rain formation
Pyroclastic fallout - material ejected e.g. Tephra. Causes buildings to collapse
Lahars - another secondary impact where ash mixes with water creating rapid flowing torrents which can bury and destroy homes
Describe a shield volcano
Basalt lava more runny
Found at constructive margins
Describe a acid dome volcano
Thick viscous lava with lots of silica
Describe a caldera
Where a violent eruptions that blows the top off a volcano
Magma chamber empties and sides cave inwards
How is the magnitude of volcanoes measured?
Volcano explosivity index
Logarithmic scale from 0-8
8 being mega colossal
What type of eruption would a large one be catergorised as
Plinian or peleean eruption
What would a small volcanic eruption be classed as?
Icelandic or Hawaiian
Give some methods of predicting an earthquake.
Seismometer - micro earthquakes will occur prior to an eruption
Tiltometers - measure ground distortion
Measuring gas levels - lots of sulphur dioxide released prior to an event
Where did the Eyjafjallajokull eruption occur?
Along the constructive plate margin between the north American and eurasian plate.
What type of volcano is eyjafjallajokull?
Describe the events taking place up to the main eruption, then what was the explosivity index value for the main eruption?
March 2010 - slow lava flows from the fissure leaked basaltic lava. Some ash clouds but not much - was a tourist attraction
April 2010 - 4 on VEI, sending ash 8Km into the atmosphere,
What caused the eyjafjallajokul eruption to be made worse?
The jet stream - west to east direction, ash up 8Km straight into the jet stream, forcing across Northern Europe
Glacier - eyjafjallajokul was located under a glacier which meant the pressure built up considerably
Other than the flight disruptions What were the impacts of the Eyjafjallajokull earthquake?
Flooding - melted ice from lava caused 800 people to be evacuated
Lava flow blocked a main road
Air quality reduced, many worried that health issues may occur
Farming - animals kept indoors, ash landed on crops (in long term increases fertiltiy)
Describe the impacts Eyjafjallajokull had on airspace, what other secondary impacts did this cause?
Ash in jet stream, meant planes couldn't fly
20 countries air space closed - 17,000 flights cancelled in 24 hours
British Airways lost around £20 million each day that planes were down
£1.3 million lost in Kenyan flower trade because these couldn't be transported quick enough to their intended destinations