volcanic hazards Flashcards
where are the 4 places volcanoes are found
-along constructive plate margins
-found w/in continental rift valleys
-on or near subduction zones eg. Ring of Fire
-hotspots
what happens if lava is viscous/v thick
gases won’t move freely, building pressure leading to explosive eruptions
what happens if the lava is thin/runny and not viscous
gases will escape easily
how are the power of volcanoes measured?
volcanic explosively index which runs from 0-8
what are the four primary effects of volcanic eruptions?
tephra
lava flow
volcanic gases
pyroclastic flows
what are pyroclastic flows like?
occur in two parts.
Along ground, lava and pieces of rock flow downhill.
Above, a thick cloud of ash forms over the fast-moving flow.
what is tephra?
solid material varying from volcanic bombs to ash which is ejected into the atmosphere
what are lava flows like and what elements determine their flow?
silica makes lava viscous and slow
whereas non viscous lava flows quickly
which gases do volcanoes emit?
-carbon dioxide
-carbon monoxide
-sulphur dioxide
-chlorine
-hydrogen
what are 6 secondary effects of volcanoes?
-lahars
-flooding
-climate change
-acid rain
-landslides
-tsunami
what are lahars
ash from recent eruption combined w/ water sweeps down river valleys, creating huge mudflow
how can eruptions cause flooding?
can melt glacier water and ice caps
eg. Iceland 1996 volcano when Grimsvotn erupted
what’s an example of tsunami caused from volcanoes?
Krakatoa, Indonesia in 1883 which killed around 36,000 people
how does acid rain form?
sulphur mixes w/ atmospheric moisture
how do volcanoes contribute to climate change?
co2 emissions
human contribution to carbon cycle is 100 times more than those from all the volcanoes in the world
