Volcanic hazards Flashcards
When is a volcano deemed as a hazard?
When it poses a threat to humans.
How is the magnitude of a volcano measured?
VEI (Volcanic Explosivity Index) from 0-8.
How to volcanologists determine the frequency of eruptions?
By looking at its previous history of eruptions.
Primary effects are…
Immediate material coming out of the volcano.
Name some examples of the primary effects of an eruption
Tephra - solid material
Pyroclastic flow - hot, high velocity flows made of tephra and gas.
Lava flows
Volcanic gases - e.g. sulphur and carbon dioxide
Secondary effects occur…
Days to weeks after the eruption.
Name some examples of the secondary effects of an eruption
Lahars - melted snow and ice combined with ash
Acid rain - gases combined with moisture in the atmosphere
Flooding - eruption melts ice caps and glaciers
Climate change
What is prediction and what does it do?
The study of previous eruption history to reduce the severity of the impacts.
Examples of prediction
Studying past lahar flows to determine flow paths
Monitoring land swelling and groundwater levels
Examples of protection
Authorities create risk assessments and alert levels
Strengthen buildings
Plan evacuation routes
When do short term responses occur? Give examples
Immediately after the event, e.g. warnings and evacuation routes
When do long term responses occur? Give examples
Days to weeks after, e.g. risk management, preparedness, mitigation and adaption.
Describe the distribution of volcanic hazards
- 75% of volcanoes located around the ring of fire
- Located on constructive and destructive plate boundaries
- Liner patterns around plate boundaries
- Not found in the middle of plates
How are volcanic hazards predicted?
Monitoring active and dormant volcanoes for signs of unusual seismic activity
Warning can be issues to governments and authorities
Describe the process of mudflows and lahars as an impact of volcanic activity:
Flows of ash, soil and rock which have been changed to clay by acids in volcanic acids and hot-spring waters
