Basics of Volcanoes Flashcards
Located along
Plate margins
Types of boundaries that allow them
Destructive and Constructive
Found near these landforms and features
Ocean ridges
Rift valleys
Subduction zones
Hotspots
E.g of ocean ridge volcano
Eyjajaffajokull, Iceland
E.g of rift valley volcano
Mt Nyirogongo, Congo
E.g of subduction zone volcanoes
Often island arcs - Marianas
West Indies
Hotspots
concentration of radioactive elements below surface
Plume of magma rises into plate
Breaks through surface
Causes shield volcano
Hot spot is stationary but plate continues to move, creating a chain of islands
Closer to the hotspot = more active volcano
Extinct volcanoes further away
E.g. of hotspot volcano
Hawaiian islands and Kiluwea
Ways of predicting volcanic hazards
Remote sensing Thermal satellite imaging Seismic activity Hydrology change Thermal tracking Seismic history Mass movement Ground deformations Gas emissions
Example to use of prediction of volcano
Nyirogongo, DRC Pressure change in lava lake Time lapse photo change CO2 pocket emissions Swellings Fissure release
Primary hazards of volcanoes (+exp)
Tephra - explosions of solid material/ volcanic bombs
Pyroclastic flow - gas and tephra charged flows 700km/hr
Lava flows
Volcanic gas release - CO2, CO, hydrogen sulfide, suphur dioxide, chlorine
Secondary hazards of volcanoes (+exp)
Lahars - mudflows from melted ice and ash
Flooding - eruptions melt glaciers
Volcanic landslides
Tsunamis - sea waves generated by volcanic eruptions displacing water
Acid rain - emitted gases combine with rain forming acid rain
Climatic change - ejection of GHG reduces global temo
How is volcanoes activity measured
VEI
Volcanic Explosivity Index
Measures by material ejected
A range from 1-8
