Module 1.4 - Volcanoes Flashcards
What is a volcano
a rupture in the earths crust that allows magma to flow upwards
Where are volanoes usually located
along divergent/convergent boundaries or at hotspots (areas where underlying mantle is much hotter than in other areas)
What is an ash cloud
a cloud of ash that forms in the air after some volcanic eruptions
What is a magma chamber
contains molten rock (magma) deep within earths crust
What is a conduit
a passage through which magma (molten rock) flows up in volcanoes
What is a vent
an opening in earths surface through which molten rocks rise to the surface
What is lava
magma coming to the surface from a volcanic eruption
What is pyroclastic flow
clouds of ash and lava fragments
What is the definiton of an erupting volano
the sudden occurance of a discharge of steam and volcanic material
What is the definiton of an active volcano
any volcano that has erupted in the last 10000 years
What is the definiton of an dormant volano
an active volcano that is not erupting, but will soon
What is the definiton of an extinct volano
a volcano that has not erupted in the last 10000 years
At what plate boundary to strato volcanoes form
converging subduction boundaries
what type of lava do strato volcanoes produce
because the subduction forces basalt oceanic crust into the mantle the lava created is much more viscous (thick) and the flow is slower
what type of explosion do strato volcanoes have?
because of the high viscosity (thickness) of the lava the volcano is explosive
what type of form do strato volcanoes take
conical mountain with steep slopes, short lava flows (because of thickness) and have a crater at summit created by explosion
At what plate boundary to shield volcanoes form
diverging boundaries and hotsports magma moves up through rift
what type of lava do shield volcanoes produce
molten, mantel rock comes to surface (mainly granite) and has a lower viscosity so the lava flows easier
what type of explosion do shield volcanoes have?
non-explosive because lava is runny and not sticky
what type of form do shield volcanoes take
gently sloping, broad summits low silica lava (spread easily, low viscous - less explosive)
Explain hot spot volcanoes (where they form how the lava comes up and island arcs)
hot spot forms away from plate boundaries over a mantle plume (hot columns of solid rock that rise through mantle by convection) When plume reaches base of lithosphere the magma over time plates moves but hotspot stay creating islands arcs
more silica =
slower flow
low viscousity
less explosive
