Volcanoes 5 Flashcards
volcanic hazard
any potentially dangerous volcanic process
ex/ lava flows, pyroclastic flows, lahars, ash falls
volcanic risk
any potential loss or damage as a result of volcanic hazard
how do we calculate risk
hazard x vulnerability
/ mitigation
hazard map: lava flows
- slow
- usually mafic + low viscosity
- not dangerous
- easy to predict path
- hard to stop
what is lava mostly hazardous to?
buildings and stuff
how can people reduce the risk of damage by lavas?
- do not build homes in valleys
- move towns away
- prevent development by making it a national park
hazard map: fire fountaining
- basaltic gas rich lava
- small explosive eruptions
- may form lava flow
- ballistic spindle bombs
fire fountaining happens only if the lava is ___
gas rich
hazard map: pyroclastic falls (ash fall)
hot ash + gas ejected from volcano
- breathing in ash is deadly
- total darkness
- roofs collapse (dangerous)
- hazard to aircraft (engines, turbulence)
pyroclastic falls have what effects on the climate?
- plinian eruptions blast ash into stratosphere -> block sun = cooling effect
- ash suspended for yrs
- SO2 can form acid rain / haze
- CO2 greenhouse warming
hazard map: pyroclastic flows
- avalanche of pyroclastic material driven by gravity
(40-400 km/hr) - usually stay in valleys but can flow over ridges
- super fast and hot
ex/ Pompeii
origin of pyroclastic flows
most common: collapse of volcanic column
2nd common: explosive collapse of lava domes
- silica rich, highly viscous
can pyroclastic flows move over water?
yes :l
why is the collapse of lava domes -> pyroclastic flows dangerous?
because it’s either boring or super dangerous, people don’t see it coming
hazard map: lahars
volcanic mud/debris flows
- can travel far
- can occur without an eruption
- prevalent at snowy/icy volcanoes
