Main Hazards Generated By Volcanic Eruptions Flashcards
What are the two main types of eruption
Effusive
Explosive
What eruption is caused by shield volcanoes
Effusive
What eruption is caused by composite/strato volcanoes
Explosive
Effusive eruptions occur at what plate boundary
Divergent plate boundaries where shield volcanoes are common
Explosive eruptions occur at which plate boundary
Convergent boundaries where composite/strato volcanoes are common
Two types of lava
Basaltic
Andesitic
Type of lava found at divergent shield volcanoes and the lavas characteristic
Basaltic lava from shield volcanoes from effusive eruptions, characteristics of the lava include low % silica and higher eruption temp with low viscosity
Type of lava found at converging composite volcanoes and the lavas characteristics
Composite volcanoes have andesitic lava from explosive eruptions, this causes the lava to have high % Silica with lower eruption temps and high viscosity
Style of eruption at shield volcanoes
Gas bubbles expand freely causing limited explosive force
Style of eruption at composite volcanoes
Violent bursting of gas bubble when magma reaches the surface causing highly explosive volcanoes which result in the vent often shattered
Materials erupted in effusive (shield) volcanoes
Gas
Lava flows
Materials erupted in explosive (composite) volcanoes
Gas
Dust
Lava bombs
Tephra
What is the frequency of effusive eruptions
Tend to have frequent eruptions continuing for months
What is the frequency of explosive eruptions
Tend to have long periods of inactivity before explosions
Shape of shield volcanoes
Gently sloping sides with lava plateaux from multiple fissures
