General = Volcanoes Flashcards
Vulcancity
Refers to all volcanic activities related to magma forced through crust
Volcano (2)
Openings in earths crust
Lava ash and gas erupt
Constructive margin - oceanic (2)
Oceanic ridges
Mid Atlantic ridge
Constructive - Continental (2+)
Rift Valley
African Rift Valley - mt Kilimanjaro
Destructive (2)
Ring of fire - Pacific Ocean
Most Violent
Intraplate (3)
Over hotspots
Middle of pacific
Hawaiian islands
Constructive type of lava
Basaltic
Constructive characteristics (3)
Runny
Less viscous
Low in silica
Constructive type of eruption (2)
Little violence
Gas escapes easily
Constructive - form (2)
Shield volcano
Lava only
Destructive - type of magma
Acidic
Destructive lava characteristics (3)
Slow flowing
Viscous
High in silica
Destructive - type of eruption
Potentially explosive
Destructive - hazards (3)
Tephra
Pyroclastic flow
Ash + gas
Destructive - form (2)
Composite cone
Layers ash and lava
Primary hazards (6)
Lava flows
Pyroclastic flow
Tephra
Nuees ardentes
Ash fallout
Gases
Secondary hazards (4)
Mudflows
Landslides
Tsunamis
Acid rain
Lava flow (2++)
Basaltic = higher temp + flows for longer
Acid lava = slower + block neck of volcano = explosions
Pyroclastic flow (3)
Hot rock, ash and gases rising
Moves at a rapid speed = up to 200m/s
Temperatures are between 350-1000°C
Tephra (3)
Solid rock ejected from volcano
Largest = 1m in diameter = death
Smallest = carried for great distances
Nuees ardente (3)
‘Glowing cloud’
Dense, rapid cloud of hot gases, ashes, and lava fragments
Type of pyroclastic flow
Ash fallout (4+)
Ejected high in atmosphere
Can cover large area
Highly abrasive = breathing problems, disrupt machinery
Obstruct sunlight, reduce visibility and temps
Volcanic gases (5)
Dominated by steam
Carbon monoxide, hydrogen sulphide, sulphur dioxide, and chlorine
Mudflows / Lahars (3)
Formed when ash and other volcanic material mix with water
Speed = 60km/h
Highly erosive
Acid rain (2+)
Volcanoes emit sulphurous gas = acidic rainwater when combined with atmospheric moisture
Magnitude (2)
Logarithmic scale
Volcanic exclusivity index
Frequency (3+)
Basaltic lava = continuous
Destructive = acidic lava infrequently = dormant
Yellowstone supervolcano = 3 times in 2.1million years
Warning signs of volcano (4)
Measure local seismic activity = seismometer
Ground deformation = tiltometer
Changes in conc. of Co2 and sulphur dioxide = remote sensing
Temp of ground water = hydrological instruments
Primary impacts examples (4+)
Direct result of volcano
Lava + pyroclastic flow = destroy roads and cause buildings to collapse
Ash = damage crops and water supply
Tephra + lava = kill people
Secondary impacts examples (5+)
Lahars = kill, injure, damage roads = emergency services stopped = more death
Business collapse = unemployment
Psychological problems = loss
Shortages of food
Fires
Protection offered through what (3+)
Risk management:
Preparedness = state of readiness
Mitigation = action of reducing severity of risk
Adaption = action if changing behaviour in order to reduce severity
Prediction involves (3)
Hazard mapping = previous lava flow = geology
Protection (5+)
Warnings issued
Instructions on how to act
Hazard maps = evacuation strategies
At risk areas = alert systems, shelters, evacuation camps
Emergency water + food supplies
How many active volcanoes
1500
% of eruptions associated with plate margins
95%
