Volcanoes Flashcards
What percentage of convergent plate margins primarily in subduction zones
80%
What percentage of volcanoes are along the mid Atlantic ridge
20%
What are the 4 types of volcanoes
Cinder cones
Shield volcanoes
Lava domes
Stratovolcanoes
What are cinder cones
Blobs of gas - charged lava area thrown into air and break into fragments
What are shield volcanoes
Wide base gentle slopes
Large
Lava is fluid slows along a long distance and solidifies slowly
What is the lava like in shield volcanoes
Basic lava with <50% silica
Shield volcanoes form on what plate margin
Constructive plate margin
What type of volcano is Mauna Loa
Shield volcanoes
Where is Mauna Loa
9000m from the ocean floor or the summit (hot spot)
What type of plate margins do stratovolcanoes form on
Convergent plate margins
What are the characteristics of a stratovolcano
Magma gains added silica as it rises through continental rocks
More viscous lava
Steeper sides
Dangerous because long dormancy
Why is long dormancy for a volcano dangerous
Pressure builds up over many years and culminates in an explosion
What are the characteristics of lava domes
Small
Steel sides, rounded tops
Lava contains >60% silica which is to viscous to flow far
What happens when a lava dome collapses
Explosive eruptions
