Volcanic Hazards

Question 1

What are volcanoes? What is vulcanicity? - Volcanic Hazards

Answer 1

Volcanoes are landforms created over openings in the Earth’s crust by an accumulation of extrusive, eruptive products.
Vulcanicity is the collection of volcanic activities related to molten rock being forced into and out of crust.

Question 2

Describe the type of volcano at constructive boundaries between 2 oceanic plates (type of lava, form of volcano, type and frequency of eruption) - Volcanic Hazards

Answer 2

Volcanoes at constructive boundaries between 2 oceanic plates are gently sloped, shallow volcanoes which are filled with basaltic lava. They create frequent but gentle eruptions which sees magma reach the surface as it spills up through a gap created by plate movement.
ICELAND - MID-ATLANTIC RIDGE

Question 3

Describe the type of volcano at constructive plate boundaries between 2 continental plates (type of lava, form of volcano, type and frequency of eruption) Give an example of these volcanoes - Volcanic Hazards

Answer 3

Volcanoes at constructive boundaries between 2 continental plates are composite volcanoes with steeper sides, filled with andesitic lava. Creates infrequent but violent eruptions that may be explosive. Magma reaches the surface as crust thins out, forcing magma to the surface.
Example - KILIMANJARO

Question 4

Describe the type of volcano at destructive plate margins (type of lava, form of volcano, type and frequency of eruption) Give an example of this type of volcano - Volcanic Hazards

Answer 4

Destructive margins produce composite volcanoes with steep sides and filled with andesitic lava. They produce infrequent and explosive eruptions, with magma reaching the surface as it is pressed upwards by the subduction of the oceanic plate.
Example - MARTINIQUE/MONTSERRAT

Question 5

What causes hot spots? - Volcanic Hazards

Answer 5

Hot spots are caused when radioactive material beneath the Earth’s crust burns the lithosphere, allowing magma to seep through and create volcanoes.

Question 6

What type of lava/volcano/eruptions exist at hot spot volcanoes? What examples of these volcanoes are there? - Volcanic Hazards

Answer 6

Lava - basaltic
Volcano - large, flat, shield volcanoes
Eruptions - frequent yet gentle
Seen on Hawaiian Islands in the Pacific

Question 7

What is basaltic lava? What is andesitic lava? (Viscosity, eruption type, silica content) - Volcanic Hazards

Answer 7

Basaltic - causes gentle eruptions, less viscous, low silica content
Andesitic - causes violent eruptions, more viscous, higher silica content

Question 8

What is the volcanic explosively index? - Volcanic Hazards

Answer 8

The volcanic explosively index is a scale which measures the severity and magnitude of an eruption on a scale of 0-8.

Question 9

What is a fissure volcano? Describe its type of eruption, silica content, lava type, plate boundary - Volcanic Hazards

Answer 9

A fissure volcano is a volcano which produces very slow moving and gentle eruptions which are low in silica content (BASALTIC LAVA). This extrudes lava which is low in silica, usually from constructive plate boundaries or hotspots.

Question 10

What is a shield volcano? Describe its type of eruption, silica content, lava type, plate boundary - Volcanic Hazards

Answer 10

A shield volcano is a flat, shallow volcano produced at constructive boundaries. This creates slow eruptions of basaltic lava which is low in silicates.

Question 11

What is a composite volcano? Describe its type of eruption, silica content, lava type, plate boundary - Volcanic Hazards

Answer 11

A composite volcano is a volcano created by numerous layers of ash and lava. It produces violent, infrequent eruptions of andesitic lava at subduction plate boundaries.

Question 12

What are primary hazards from volcanoes? What are secondary hazards? - Volcanic Hazards

Answer 12

Primary - lava flow, pyroclastic flow, tephra, nuées ardentes, ash fallout, volcanic gases
Secondary - mudflows/lahars, acid rain

Question 13

What is a lava flow? What are their impacts? Where do these occur? - Volcanic Hazards

Answer 13

Lava flows are runny or viscous flows of lava depending on the temperature and composition of the lava. These are produced during volcanic eruptions and can travel at up to 40km/h, burning down structures or vegetation.
Occur at subduction zones, constructive margins and hot spots.

Question 14

What are pyroclastic flows? What are their impacts? Where do they occur? - Volcanic Hazards

Answer 14

Pyroclastic flows are fast-moving flows of hot gas, rock and ash which can reach speeds of 700km/h. They travel downhill, causing instant death. Seen at Pompeii.
Occur at subductive margins with composite volcanoes.

Question 15

What is tephra? What are their impacts? Where does it occur? - Volcanic Hazards

Answer 15

Tephra is rock material ejected by a volcano - anything from ash to large volcanic bombs. May destroy crops, can cause the closure of airspace.
Occurs at subduction margins.

Question 16

What are nuées ardentes? What are their impacts? Where do they occur? - Volcanic Hazards

Answer 16

Nuées ardentes are dense, slower moving types of pyroclastic flow.
These occur at subduction zones.

Question 17

What is ash fallout? What are its impacts? Where does this occur? - Volcanic Hazards

Answer 17

Ash fallout is thrown up into the atmosphere by large eruptions, small fragments of material. May be carried by winds over long distances, causing major disruption to daily life, poisoning water sources or collapsing buildings.
Occurs at constructive plate margins, destructive subduction margins.

Question 18

What are volcanic gases? What are their impacts? Where do they occur? - Volcanic Hazards

Answer 18

Volcanic gases are toxic gases released by eruptions (CO2, SO2) which can be deadly to life and may cause significant damage. Can also form volcanic fog, irritate eyes/lungs/nose/throat.
Occurs at all types of volcano.

Question 19

What is acid rain? What are its impacts Where does this occur? - Volcanic Hazards

Answer 19

Acid rain is when CO2/SO2 combines with water in the atmosphere to create sulphuric or carbonic acid. This pollutes surface water, damages crops and enhances weathering.
Occurs at all volcanoes.

Question 20

What are mudflows/lahars? What are their impacts? Where do they occur? - Volcanic Hazards

Answer 20

Lahars are very thick mudflows formed when ash, rock and mud combine with rainwater. They travel very quickly and can result in major damage to the environment and structures in their path.
Occur at composite volcanoes at subduction boundaries.

Question 21

What hazards result from frequent, mild, basaltic eruptions? - Volcanic Hazards

Answer 21

Frequent, mild, basaltic eruptions produce: lava flows, tephra, volcanic gases and acid rain.

Question 22

What hazards result from explosive, andesitic and infrequent eruptions? - Volcanic Hazards

Answer 22

Lava flows, lahars, pyroclastic flows, acid rain, nuées ardentes, ash fallout and tephra.

Question 23

What are the 4 ways in which hazards may be mitigated? - Volcanic Hazards

Answer 23

Monitoring - watching hazard formation
Prediction - predicting where/when a hazard may emerge
Protection - taking measures to protect vulnerable areas
Planning - planning how to survive in the event of a hazard

Question 24

What methods can be used to predict and monitor volcanic hazards? - Volcanic Hazards

Answer 24

Looking at historical records to predict when hazards may occur, using seismometers that may detect seismic activity (indicating an eruption), measuring for ground deformation with tiltmeters, observing whether a change in gas concentration has occurred with equipment, measuring temperature of groundwater to indicate whether eruption will occur, map the impacts of previous hazards.

Question 25

How can volcanic eruptions be prepared for? - Volcanic Hazards

Answer 25

Hazards can be prepared for by issuing electronic warnings and raising awareness, education on what to expect during an eruption, hazard maps can be used to inform evacuation strategies and emergency supplies.

Question 26

What examples of building adaptions to volcanic eruptions exist? - Volcanic Hazards

Answer 26

Use of concrete frames instead of timber in order to strengthen buildings against ash fallout, steep sloped roofs prevent ash accumulation, windows facing the volcano allow people to observe hazards and react.

Question 27

Where is Eyjafjallajökull located? - Volcanic Hazards

Answer 27

Eyjafjallajökull is located in Iceland, along the Mid-Atlantic Ridge, in a fairly rural section of the country. 125km from Reykjavik, ice caps top the volcano.

Question 28

When did Eyjafjallajökull erupt? What hazards were INITIALLY generated by this? - Volcanic Hazards

Answer 28

Eyjafjallajökull erupted in April 2010. Lava flows began flowing to the North-East of the volcano, while initially a small ash ejection began.

Question 29

On what date did Eyjafjallajökull begin to erupt more violently? What impacts followed this violent eruption? - Volcanic Hazards

Answer 29

Eyjafjallajökull began to erupt violently on the 14th April 2010, ejecting fine, glass-rich ash into the atmosphere at over 8km in height.

Question 30

What level on the volcanic explosivity index did Eyjafjallajökull reach in its most violent phase? - Volcanic Hazards

Answer 30

Eyjafjallajökull reached level 4 on the volcanic explosivity index in its more violent phase.

Question 31

What primary impacts were generated by the eruption of Eyjafjallajökull IN ICELAND? - Volcanic Hazards

Answer 31

Eyjafjallajökull led to the melting of glacial ice which caused flooding in local areas, saw ash fall on local farmland which prevented grazing, harvesting and farming, blocked local roads, closed Reykjavik Airport.

Question 32

What international impacts were there from the eruption of Eyjafjallajökull? (How many flights cancelled, how many people affected?) - Volcanic Hazards

Answer 32

Eyjafjallajökull’s eruption saw major international disruption as ash fallout was exploded into the jet stream, which affected European airspace. 100,000 flights were cancelled and 10 million people were impacted.

Question 33

What (negative) secondary environmental and (positive) secondary economic impacts resulted from the eruption of Eyjafjallajökull? - Volcanic Hazards

Answer 33

Environmental: ash production from the eruption resulted in eye irritations and dry throats. Ash mixed with flood waters to create lahars which channelled into rivers.
Economic: initial tourism created by minor eruptions, with 10,000 people visiting by April 2010. Tourism did decline into the Summer.

Question 34

What immediate local responses were there to the eruption of Eyjafjallajökull? - Volcanic Hazards

Answer 34

800 people were evacuated from the area due to flood risk, farmers had to keep livestock indoors to protect them from ash, gaps were created in road in order to release water and reduce infrastructure stress, schools were closed.

Question 35

What immediate international responses were there to the eruption of Eyjafjallajökull? - Volcanic Hazards

Answer 35

A six day shutdown of airspace ensued in order to reduce risk to planes as a result of the ash cloud, the Royal Navy collected soldiers returning from Afghanistan (as well as holiday makers in Spain).

Question 36

What long-term responses were there to the eruption of Eyjafjallajökull? - Volcanic Hazards

Answer 36

Local roads and flood defences were reconstructed, Katla (neighbouring volcano) monitored due to being overdue an eruption, tourist attractions were created at Eyjafjallajökull, insurance companies reviewed ash cloud policies.

Question 37

How much money did international airlines lose from the eruption of Eyjafjallajökull? How much money did UK travel agents lose per day? - Volcanic Hazards

Answer 37

Airlines lost £1.2bn as a consequence of the eruption, while UK travel agents lost £6m per day.

Question 38

What impacts on international travel and events did the eruption of Eyjafjallajökull have? - Volcanic Hazards

Answer 38

Saw the cancellation of the Japanese Motorcycle Grand Prix and Boston Marathon, meant teachers and students could not return from holidays.