volcanoes Flashcards
definition
fissure (effusive) eruption
eruption occurs through linear fissures, passive lava flow of basaltic magma, shield volcano
definition
cental vent eruption
explosive eruption localized at vent, powerful flow of felsic magmas, ash plume, composite volcano
volcanic deposits from explosive eruptions
ash plume (ejecta cloud), ash fall, pyroclastic flow deposit (hazardous >100km/hr flow of hot gasses)
fissure (effusive) eruptions
examples
Icelandic, Hawaiian
explosive eruptions
examples
Plinian eruption, Vulcanian eruption (St. Helens), Pelean eruption, Strombolian eruption (Italy)
from most powerful to least
Plinian’s ash plume reaches into the stratosphere and blocks sunlight
what causes explosive versus effusive eruptions
- composition of magma
- viscosity of magma
interplate volcanoes
mid-ocean ridges, subduction zones, continental rifts
intraplate volcanoes
mantle plume (hot spots)
stratovolcano
also composite volcano
distinct crater, alternating layers of pyroclastic fragments (ash and solidified lava of varying composition), felsic to intermediate, viscous lava flows
from explosive eruptions
stratovolcano
tephra
layers of ash from previous eruptions
shield volcanoes
small vents at the top, mafic magma chambers, low viscosity basaltic flows,
locations (tectonic)
effusive eruptions
mid-ocean ridges, hotspots, continental rifts
location
explosive eruptions
subduction zones, water (silica) rich minerals tend to more viscous magma
pillow lavas
form at mid-ocean ridge volcanoes when basalt erupts under water
Pahoehoe lava flow
ropey lava, low volume flow, slow, quiet, smooth surfaces when cooled, low viscosity
Aa lava flow
crumbly, rubble-like lava, large volume flow, fast flow, viscous, rough surface composed of clinkers
clinkers are loud (think breaking glass)
hot spot track
forms as plate moves on top of a stationary mantle plume, begin as submarine volcanoes, shield volcanoes form once islands emerge from water
eruption occurs through linear fissures, passive lava flow of basaltic magma, shield volcano
definition
fissure (effusive) eruption
explosive eruption localized at vent, powerful flow of felsic magmas, ash plume, composite volcano
definition
cental vent eruption
ash plume (ejecta cloud), ash fall, pyroclastic flow deposit (hazardous >100km/hr flow of hot gasses)
volcanic deposits from explosive eruptions
Icelandic, Hawaiian
fissure (effusive) eruptions
examples
Plinian eruption, Vulcanian eruption (St. Helens), Pelean eruption, Strombolian eruption (Italy)
from most powerful to least
Plinian’s ash plume reaches into the stratosphere and blocks sunlight
explosive eruptions
examples
- composition of magma
- viscosity of magma
what causes explosive versus effusive eruptions
mid-ocean ridges, subduction zones, continental rifts
interplate volcanoes
mantle plume (hot spots)
intraplate volcanoes
distinct crater, alternating layers of pyroclastic fragments (ash and solidified lava of varying composition), felsic to intermediate, viscous lava flows
from explosive eruptions
stratovolcano
also composite volcano
layers of ash from previous eruptions
stratovolcano
tephra
small vents at the top, mafic magma chambers, low viscosity basaltic flows,
shield volcanoes
mid-ocean ridges, hotspots, continental rifts
locations
effusive eruptions
subduction zones, water (silica) rich minerals tend to more viscous magma
location
explosive eruptions
form at mid-ocean ridge volcanoes when basalt erupts under water
pillow lavas
ropey lava, low volume flow, slow, quiet, smooth surfaces when cooled, low viscosity
Pahoehoe lava flow
crumbly, rubble-like lava, large volume flow, fast flow, viscous, rough surface composed of clinkers
clinkers are loud (think breaking glass)
Aa lava flow
forms as plate moves on top of a stationary mantle plume, begin as submarine volcanoes, shield volcanoes form once islands emerge from water
hot spot track