Volcanic Hazards

Question 1

Describe the distribution of volcanoes

Answer 1

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

Question 2

Give five types of volcanic hazard

Answer 2

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

Question 3

Describe a shield volcano

Answer 3

Shallow sided 
Broad
Basalt lava more runny
Found at constructive margins
Gentle eruptions

Question 4

Describe a acid dome volcano

Answer 4

Steep sides
Thick viscous lava with lots of silica
Destructive margins
Explosive eruptions

Question 5

Describe a caldera

Answer 5

Where a violent eruptions that blows the top off a volcano

Magma chamber empties and sides cave inwards

Question 6

How is the magnitude of volcanoes measured?

Answer 6

Volcano explosivity index
Logarithmic scale from 0-8
8 being mega colossal

Question 7

What type of eruption would a large one be catergorised as

Answer 7

Plinian or peleean eruption

Question 8

What would a small volcanic eruption be classed as?

Answer 8

Icelandic or Hawaiian

Question 9

Give some methods of predicting an earthquake.

Answer 9

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

Question 10

Where did the Eyjafjallajokull eruption occur?

Answer 10

Along the constructive plate margin between the north American and eurasian plate.

Question 11

What type of volcano is eyjafjallajokull?

Answer 11

Caldera

Question 12

Describe the events taking place up to the main eruption, then what was the explosivity index value for the main eruption?

Answer 12

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,

Question 13

What caused the eyjafjallajokul eruption to be made worse?

Answer 13

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

Question 14

Other than the flight disruptions What were the impacts of the Eyjafjallajokull earthquake?

Answer 14

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)

Question 15

Describe the impacts Eyjafjallajokull had on airspace, what other secondary impacts did this cause?

Answer 15

Ash in jet stream, meant planes couldn’t fly
20 countries air space closed - 17,000 flights cancelled in 24 hours
GLOBAL IMPACT
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

Question 16

Deecribe some of the responses to the Eyjafjallajokull earthquake

Answer 16

Research into better engine design
Insurance reviewed policies regarding this type of event
British citizens sailed across channel to pick up those stranded
The no fly zone was a response in itself