Volcanoes Flashcards
Lava flow
melted rock that flows across the land
pyroclastic debris / tephra
ash/rock that is blasted by gases into the air and falls back to the surface
Volcanoes are created from accumulating…
lava, pyroclastic material, or a combonation of both
what in magma/lava causes it to become thick
silica
viscosity
magma’s resistance to flow
mafic lava
low viscosity
less than 50% silica
intermediate lava
high viscosity
50 to 64% silica
felsic lava
high viscosity
65% to 70% silica
volcano eruption styles related to (2)
composition and viscosity
caldera
collapse feature formed from volcanic eruptions that empty magma chambers
crater
bowl-shaped area that surrounds the volcano’s vent
explosive eurptions
volcanoes release clouds of ash and avalanches of debris by blasting; common with thick lava that traps gases
effusive eruptions
volcanoes release only flows or fountains of lava; common with very hot, fluid/runny lava
lava fountian
lava spurts into the air due to rapid expansion of gas bubbles
lava lakes
formed when lava pools within the crater that surrounds the volcano’s vent
sheild volcanoes (4)
-formed by thin lava flow (malfic)
-very large, broad with gentle slopes
-largest
-hazards: tephra, vog
cinder volcanoes (3)
-formed from fine-grained tephra
-small with moderate slopes
-hazards: ash, tephra, lava flows sometimes
composite / stratovolcanoes (4)
-formed from thick lava
-large with steep slopes
-violent eurptions
-all hazards
hazards
lava flow
tephra
pyroclastic flow
lahar
eurption column
lava domes (3)
-formed from thick lava
-Small, steep sided features that are the result of thick lava piles
-often form in craters
