volcanoes Flashcards
distribution
along constructive, destructive plate margins and hotspots
hotspots=
in areas there’s a concentration of radioactive elements below the crust which causes hotspots to develop. a plume of magma rises when the lava breaks through the surface its active
magnitude
its measured using the VEI
- the more powerful= the more explosive
- its a logarithmic scale from 0-8 (7-8) being the most explosive) it considers how long it lasted, how much tephra erupted and how high
- IT DOESNT TAKE INTO ACCOUNT GAS EMISSIONS
frequency
frequency varies per volcano.
- they are classes as active, dormant ( a volcano that’s erupted in the past but unlikely to soon) or extinct
- the higher frequency of eruptions means there effusive (less powerful)
regularity
volcanoes erupt regularly on each type of boundary
destructive margins are more explosive but they can be irregular
predictability
- SEISMOMETERS= used to measure earthquakes near eruptions to determine if an eruption will occur
- TILTMETERS=they monitor changes in the landscape as volcanoes swell
- RISING GROUND WATER, TEMP AND GASES= the rising magma heats the ground water and interrupts with the gases making it more acidic
- MAGMETOMETERS= if there’s changes in magnetism it indicates magmas rising
- REMOTE SENSING CAMERAS= satellites can monitor thermal activity like upwelling
- THERMAL IMAGING= satellites can monitor hydrothermal activity
- GAS SAMPLING= gases can escape before magma reaches the surface. if the concentration increases its likely to erupt
primary effects
- LAVA FLOWS= lava can flow quickly or slowly depending on viscosity
- PYROCLASTIC FLOW= hot gases, ash and volcanic rock that flows down the side of a volcano at speeds up to 700 km/hour
- TEPHRA= solid materials like volcanic bombs and ash are ejected into the atmosphere
secondary effects
- LAHARS(mudflows)= melted snow and ice from an eruption combined with volcanic ash forms mud flows that move down river valleys at high speeds
- FLOODING= when there’s an eruption melted glaciers and ice caps cause flooding
- TSUNAMIS= if an eruption occurs at the coast, material can displace water and cause a tsunami
- ACID RAIN= volcanoes emit gases like sulphur. this combined with moisture in the air causes acid rain
- CLIMATE CHANGE= volcanic debris can block the suns rays which reduces the climate
- LANDSLIDES
primary impacts of volcanoes
ENVIRO- ecosystems damaged and wildlife killed
ECONOMIC- businesses and industries destroyed
SOCIAL- people killed and homes destroyed
POLITICAL- government buildings destroyed
secondary impacts of volcanoes
ENVIRO- water acidified by acid rain, gases contribute to greenhouse effect
ECONOMIC- jobs lost but profit for tourism
SOCIAL- floods and homelessness
POLITICAL-conflict concerning response and food shortages
responses
PREVENTION=they can’t be prevented but the risk to people can be
PREPARDNESS= monitoring volcanoes means warnings can be given out. education on volcanoes can help people know what to do if there’s a volcanic eruption. evacuations can be planned and training for response teams
MITIGATION= intervene with the volcano(concrete blocks to steer lava away from the area), strengthens buildings that are at risk of mudflows, have more emergency aid and rescue
ADAPTATION= move away from an area and encourage more tourism
difference between shield and composite volcano
composite= tall steep cones that produce explosive eruptions
shield= large gentle sloped mounds from effusive eruptions
difference between andestic and basaltic lava
andestic= high viscoscity (thick and slow moving) due to high amount of silica (melting crust) cause lava domes to build due to build up of lava which becomes unstable and can collapse
balsaltic= less viscous and more runny(hot mantle). causes greater destructive and can flow further causes wider damage especially to property and land
