Composite Volcanoes
These types of volcanoes are also known as a stratovolcano. This is the type of volcano most commonly imagined.
It is a cone shaped mountain with steep, smooth, barren slopes often with a single plume of smoke emitted from a single central vent. It is composed of alternating layers or strata of material created by pyroclastic (lava) flows. Liquid magma is emitted from a reservoir deep in the earth's crust.
In Costa Rica the Poas, Arenal, and Irazu volcanoes are examples of composite volcanoes.
Shield Volcanoes
A large volcanic structure with long gentle slopes built up almost entirely from fluid lava flows. Shield volcanoes erupt nonexplosively, producing fluid lavas that can flow great distances from the active vents. Although these eruptions may destroy property, they rarely cause death or injury.
The shape of this type of volcano is more like a dome than a tall cone. This type of volcano is built slowly and can have multiple vents producing lava flows.
The largest active volcano in the world is a shield volcano in Hawaii named Mauna Loa. It stands almost 5 1/2 miles high (3 miles under water and 2 1/2 miles above sea level). Almost 5 miles of this volcanic structure is buried into the Pacific plate below ground level which if included makes this structure about 10 miles in height!
Cinder Cone Volcanoes
A cone structure built by an accumulation of loose bits of magma called scoria that fall around a vent or crater after being expelled during moderately explosive activity.
They are the simplest of volcano structures and are prevalent in Western North America and elsewhere in the world.