Nature and Distribution of Volcanoes

Hazards

Types of Volcanoes

• Shield

• Composite

Shield Volcano Characteristics

• Broad and gentle sloping

• Basaltic lava that has low viscosity

• Generally effusive and frequent

• Constructive plate boundaries

• Mauna Kea in Hawaii

Composite Volcano Characteristics

• Steep sided and cone shaped

• Andesitic lava that has high viscosity

• Violent and frequent

• Destructive plate boundaries

• Mount Etna in Italy

Locations of Volcanoes

• Ocean ridges (constructive boundary)

• Rift valleys (constructive boundary)

• Subduction zone (destructive boundary)

• Hotspots

Hotspots

Very hot areas within the mantle that are often located far from tectonic plate boundaries and produce magma plumes

Magma Plumes

Narrow columns of super hot rock that rises from deep within the mantle and melts the crust above.

Benioff Zone

Sloping plane of earthquakes that marks the path of a sinking, subducting tectonic plate