Types of Volcanoes

Cinder Cone

A cinder cone is a type of volcano that is made of loose rock fragments that have been ejected from the volcano. Cinder cones are the smallest types of volcanoes. They have very steep slopes. Cinder cones are often associated with other larger volcanoes and are often found in groups.

Examples

Sunset Crater, Arizona

300m high

1,000m diameter

35 degree slope

Paricutin, Mexico

Erupted 1943 -1946

 

 

Composite Cones

Composite cones or stratovolcanoes are large, nearly symmetrical structures composed of alternating lava flows and deposits of rock fragments. The type of lava that forms a composite cone is very viscous (viscous means that the fluid does not flow easily). The viscous lava results in a volcanic cone that is steep (since the lava piles up). Composite cones are steeper than cinder cones at the top but become more gently sloping at the base. These types of volcanoes are common around the "Ring of Fire" the coasts of the continents around the Pacific Ocean. In the US these are the volcanoes in the Cascade Mountains including Mt. Saint Helens, which erupted in 1980.

Examples

Mt. Rainier, Washington

3,000 meter tall

12,000 meters diameter

40 degree slope, top half

20 degree slope, bottom half

Mt Saint Helens,

Oregon

Erupted 1980

Mt. Shasta, California

 

 

 

Mt. Fuji, Japan

 

 

 

 

 

Kilimanjaro, Tanzania

These volcanoes erupt explosively often resulting in pyroclastic flows (the most deadly product of a volcanic eruption). A pyroclasic flow is a very fast moving (125 mph) eruption of hot gas, rock fragments and ash that speeds down the slopes of the volcano. These flows can travel up to 60 miles from the volcano. Flows from Mount Vesuvius killed the citizens and buried the city of Pompeii in 79 AD.

 

Shield Volcanoes

The largest type of volcano are shield volcanoes. Unlike composite or cinder cones, these volcanoes are gently sloping. The type of lava that forms shield volcanoes flows very easily (has a low viscosity) and so it does not pile-up like the lava that forms a composite cone. Shield volcanoes are common in the Hawaiian islands.

Examples

Mauna Loa, Hawaii

9,000 meters tall

100,000 meters in diameter

10 degree slope

Mauna Kea, Hawaii

 

Kilauea, Hawaii

Currently erupting

Eruption began 1983

Eruptions of shield volcanoes are not as violent as composite cone volcanoes. Smooth flows of lava erupt from fissures and move down the volcano. These flows travel up to a couple of miles per hour.