Classification of Volcano: Shape Pt 3

Tephra Cone

Internal View of Tephra Cone volcano
Source: http://pubs.usgs.gov/gip/volc/fig8.gif

Cinder cones are the simplest type of volcano. They tend to be mainly explosive volcanoes, but they can also issue lavas. They are small volume cones consisting predominantly of tephra that result from eruptions consisting of rhyolitic and andesitic materials. They are actually fall deposits that are built surrounding the eruptive vent. They show an internal layered structure due to the varying intensities of the explosions that deposit different sizes of pyroclastics. They grow rapidly and soon reach their maximum size, not exceeding 250 meters in height and 500 meters in diameter, although some may rise to as high as 650 meters or more. Cinder cones can occur alone or in small to large groups or fields and most of them have a bowl-shaped crater at the summit. The gradual decrease in volume of the fallout materials (ash, lapilli) at greater distances from the vent leads to gentler slopes at the base of the cone. Cinder cones are commonly found in western North America as well as throughout other volcanic terrains of the world.

Pu`u ka Pele on the flanks of Mauna Kea, Hawaii
Source: http://volcanoes.usgs.gov/Imgs/Jpg/Photoglossary/30424305-084_large.JPG


Mt. Veniaminof in Alaska in its final stages of eruption in 1983-1984
Source: http://volcanoes.usgs.gov/Imgs/Jpg/Veniaminof/dds40-057_large.jpg