Volcanic Activity Flashcards
Primary effects
- tephra
- pyroclastic flows
- lava flows
- volcanic gases
Tephra
Solid material of varying grain size, from volcanic bombs to ash particles, ejected into the atmosphere
Pyroclastic flows
Very hot (800 degrees c), has charged, high velocity flows made up to a mixture of gases and tephra
Volcanic gases
Including co2, carbon monoxide, hydrogen sulphide, sulphur dioxide and chlorine.
Example of volcanic gases event
Emissions of carbon dioxide from Lake Nyos in Cameroon in 1986 suffocated 1,700 people
Secondary effects
- Lahars
- Flooding
- tsunamis
- volcanic landslides
- climate change
Lahars
Volcanic mud flows such as those that devastated the Colombian Town of Armedo
Flooding
Melting of glaciers and ice caps such as the Grimsbotn glacial burst on Iceland in November 1996
Tsunamis
Giant sea waves generated after violent caldera forming events such as that which occurred on Krakatoa in 1883- drowned 36,000 people
Climatic change
The ejection of vast amounts of volcanic debris into the atmosphere can reduce global temperatures and is believed to have been an agent in past climate change
When do volcanic effects become a hazard
When they impact upon the human and built environments, killing and injuring people, hurrying and collapsing buildings, destroying the infrastructure and bringing agricultural activities to a halt.
