3.1.5.3 Volcanic Hazards Flashcards
Spatial Distribution of Volcanic Hazards
Along constructive or destructive plate boundaries, or located on hotspots.
How is the magnitude of vulcanicity measured?
Using the Volcanic Explosivity Index. The more powerful, the more explosive.
Frequency of volcanic eruptions
Frequency of eruptions varies per volcano. Volcanoes are classed as either
active, dormant or extinct.
An estimated 50-60 volcanoes erupt each month, meaning volcanic eruptions are always frequent (and some volcanoes erupt constantly).
The frequency of volcanic eruptions hasn’t changed much in recent history.
Predictability of volcanic eruptions
Regularity of eruptions can help estimate when eruptions will take place (i.e.
every 10 years).
Seismic activity, gases releasing, elevation etc. can all indicate an imminent eruption, but there is no definite predictions to a volcanic eruption.
Primary hazards of volcanos
- Pyroclastic flows / Nuées ardentes - clouds of burning hot ash and gas that collapses down a volcano at high speeds
- Tephra - any type of rock that is ejected by a volcano
- Lava flows
- Ash fallout
- Volcanic gases - released during some eruptions
Secondary hazards of volcanos
- Lahars / mudflows - caused by a number of reasons, usually by melting ice at high latitudes
- Landslides
- Acid rainfall - caused when gases such as sulphur dioxide are released into the atmosphere.
- Flooding - from melting ice sheets or glaciers at high latitudes.
Regularity of volcanic eruptions
Volcanic eruptions are regular in that the eruptions on each type of boundary are similar (e.g. eruptions on destructive boundaries will regularly be more explosive than at constructive boundaries).
Sometimes eruptions may be irregular and not fit patterns.
Primary Environmental Impact
- Ecosystems damaged through various volcanic hazards
- Wildlife killed
Secondary Environmental Impact
- Water acidified by acid rain
- Volcanic gases contribute to greenhouse effect (sulphuric acid aerosols counter this and lead to global cooling)
Primary Economic Impact
- Businesses and industries destroyed or disrupted
Secondary Economic Impact
- Jobs lost
- Profit from tourism industry (possible loss and gain)
Primary Social Impact
- People killed
- Homes destroyed from lava/pyroclastic flows
Secondary Social Impact
- Fires can start which puts lives at risk
- Mudflows or floods
- Trauma
- Homelessness
Primary Political Impacts
- Government buildings and other important areas destroyed or disrupted
Secondary Political Impacts
- Conflicts concerning government response, food shortages, insurance etc.
