vulcanicity
- Created by: michael-j-inman
- Created on: 24-01-14 09:34
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- vulcanicity
- minor forms of extrusive activity
- hot springs and boiling mud
- a release of hot water from under the surface without a build up of pressure.
- often form pools
- can contain lots of dissolved minerals
- like geysers water seeps underground and is heated by vulconicty
- often form pools
- mud pools formed through the water emerging in soft rock
- hydrogen sulphide created in steam making it acidic thus dissolving the surrounding rock further
- makes clay and mud that mix with water making the mud pool
- e.g.: blue lagoon spa iceland
- makes clay and mud that mix with water making the mud pool
- hydrogen sulphide created in steam making it acidic thus dissolving the surrounding rock further
- a release of hot water from under the surface without a build up of pressure.
- geysers
- explosive plumes of water and steam erupting from the ground
- due to water seeping through fissures collected in caverns
- heated by vulconicity through hot rock from magama intrusions
- water reaches boiling point resulting into a build up of pressure
- the steam created rises through the vent thus making the geyser
- the vent then refills with water and the process starts again
- the steam created rises through the vent thus making the geyser
- water reaches boiling point resulting into a build up of pressure
- heated by vulconicity through hot rock from magama intrusions
- due to water seeping through fissures collected in caverns
- e.g.: the great geyser in Iceland
- explosive plumes of water and steam erupting from the ground
- fumeroles
- patches of escaping gas from small vents can deposite sulphur around its edge
- gas usually co2 or hydrogen sulphide
- fromed by boiling water below the surface releasing steam or when magma releases vapours such as so2
- gases escape through the surface through the vents
- feature of both active and dormant volcanoes
- patches of escaping gas from small vents can deposite sulphur around its edge
- hot springs and boiling mud
- volcano hazards
- factors effecting hazard
- the direction of blast
- the energy of blast
- type of eruption explosive/ effusive
- lava viscosity (thickness)
- surface conditions
- lava flows
- Generally not dangerous though causes serious damage though one example of a stpsided lava flow Myirangones in the Congo.
- tephra
- solid material blasted into the atmosphere (blocks or lava bombs) that are larger than 64mm can get to 8-30 tonnes smaller stuff is lapilli and fine stuff smaller than 2mm is ash
- gasses
- gasses emitted from an eruption can be toxic/ corrosive and flow down the volcano acting as a silent killer a common toxic a=gas is CO2 can lead to form acid rain
- pyroclastic flows
- avalanches of hot rock and ash that can reach speeds of 450mph can be formed from a dome collapse or a ash cloud loosing heat and collapsing
- explosive blasts
- measured on the volcanic explosion index (EPI)
- lahas
- mudflows from melted ice/snow can be fast flowing and travel along valleys heavy rain too can form lahars from the steam of a volcanic eruption
- tsnamiis
- a section of volcano falling into the sea displacing it
- flooding
- melting glaciers/ snow can carry huge blocks of ice
- climate change
- volcanic debris can reduce global tempratures
- factors effecting hazard
- forms of intrusive activity
- batholiths
- a cooled magma chamber made up from igneous rock from the cooling of magma
- domed shape hundreds km in diameter the extreme heat of its formation alters the surrounding rock through metamorphism changing the rock type e.g. marble is metamorphosed lime stone
- e.g. Dartmoor and the isle of arran
- sills
- horizontal inclined magma intrusion along the bedding planes of rock
- formed like the dyke and also like the dyke surrounding rock can be eroded away revealing the more resilient igneous rock exposed on the surface
- horizontal inclined magma intrusion along the bedding planes of rock
- dykes
- vertical crack or fissure in filled with magma that has solidified
- magma exploits any weaknesses in the rock
- when it intrudes into the lithosphere cutting through the country (natural rock) it cools
- the magma crystaslises forming igneous rock
- surrounding rock types can erode over time leaving the more resilient dyke exposed on the surface
- the magma crystaslises forming igneous rock
- when it intrudes into the lithosphere cutting through the country (natural rock) it cools
- magma exploits any weaknesses in the rock
- vertical crack or fissure in filled with magma that has solidified
- batholiths
- the forming of magma
- hydration melting where water escapes as steam that lowers the melting temperature of the overlying rock
- decompression melting due to a drop in pressure allowing the rock to melt
- minor forms of extrusive activity
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