Volcanoes Flashcards
What is a volcano?
A mountain or hill, typically conical, having a crater or vent in which particles have or are being erupted from the earth’s crust.
How much volcanism occurs under the sea?
80%
How many volcanoes are potentially active?
1500
Why are there volcanoes?
They are a mechanism for heat and mass transfer from the earth’s crust
What type of volcanoes form on divergent margins?
Effusive volcanoes. Generally producing voluminous and pillow lava. Andesite volcanoes
What type of volcanoes are produced on convergent margins?
Low density. Continental or island arcs. Shield volcanoes
What type of volcanoes are produced on intraplate volcanoes?
Rhyolite volcanoes. Low viscosity, effusive eruptions.
What are the two eruption styles of volcanoes?
Effusive (forms lava domes or flows) and Explosive (fragmented magma)
State the credentials of Basalt volcanoes
Low viscosity. Low gas content. Low silica content
State the credentials of Rhyolite volcanoes
Plumes are buoyant. High viscosity, silica and gas content. Slow moving magma
What are pyroclastic flows?
Lava plume failure. High gas content. Fast travelling
How can H2O affect a volcano?
It can chill a lava flow. It can enhance explosivity through increased vigour.
State the credentials of fissure volcanoes
Formed on divergent plate margins.
Effusive basaltic magma.
Lateral lava flows
State the credentials of shield volcanoes
Basaltic lava flows.
Built by succession
State the credentials of composite cones
Successive pyroclastic and lava material.
All types of explosions and flows
