VOLCANOS Flashcards
how many people live within 100km of a active volcano
estimated 800 million
where can active volcanos be found
constructive boundaries - Iceland
destructive boundaries - ring of fire
hot spots - Hawaiian
what scale is used to measure volcanic activity
VEI scale
what are the weakness using the VEI scale
doesn’t account for gas emissions
what is the relationship between magnitude and frequency of volcanic events
when the magnitude of the eruption increases the frequency of eruptions of the volcano decreases
what are the 4 primary effects from volcanic activity
tephra
pyroclastic flows
lava flows
volcanic gases
tephra
soil material of various sizes ranging from volcanic bombs to ash ejecting into the atmosphere
pyroclastic flows
very hot
high velocity flows made up of gas a tephra
travel up to 700km per hour
volcanic gases
co2
carbon monoxide
chlorine
sulphur dioxide
hydrogen sulphide
what are the 5 secondary effect
Lahars
floods
volcanic landslides
acid rain
climatic change
define Lahars - mudflows
melted snow and ice from eruption combined with volcanic ash forms mudflows that move down river valleys at high speeds
define floods after a volcanic eruption
eruptions melt glaciers and ice caps
serious flooding results
define volcanic landslides and tsunamis
sea waves generated by large volcanic eruptions
destructive and deadly
define acid rain
volcanoes emit gas which includes sulphur and then combined with moisture acid rain results
climatic change
ejection of huge amounts of volcanic debris into the atmosphere
can reduce climate change
how can volcanic activity be monitored and predicted
gas
remote sensing
ground vibrations
deformation
example of lava flows
congo
mt nyiragongo
fluid lava moving downhill at speeds of 90km/h
January 2002
warnings allowed for evacuation
1 on the VEI scale
147 deaths
water and power suplies destroyed
example of pyroclastic flow
montserrat
caribbean
south American plate subjects under the Caribbean plate
lava domes form and a result of viscous , silica- rich lava building onto of volcanos
when too heavy they collapse which leads to pyroclastic flows
ash eruptions led to research which found out the volcano wasn’t extinct but dominant
June 25 - collapsed and 5 million cubic metres of rock down its sides
2/3 houses burnt / flattened
19 killed
1100o evacuated
example of mudflows - lahars
Columbia 1985
rising magma and gas and steam emissions began melting the Sumit of Mt Nevado del Ruiz
melting continued till full eruption
30 m high lahars travelled over 80km/h over town Armero
2100 died
8m of mud followed the following morning
what are 2 ways people can be protected from volcanic events
land use planning
diversion of lava flows
diversion of lava flows in protection from volcanic activity
on Mt Etna in Scilly digging trenches and dropping blocks into the lava stream and using explosives has been successful in slowing down the lava flows
sea water is used to solidify lava and slow it down
land use planning in protection from volcanic activity
areas off greater risk can be identified and not built on
hazard risk assessment
responses to volcanic activity
immediate and long term
immediate lava flow- warnings, evacuations, attempts to stop
long term- monitoring research
buildings barriers in anticipation of lava flows
what are the 5 types of volcanos
fissure volcano
shield volcano
dome volcano
composite volcano
caldera volcano
