Types of volcano

There are three different types of volcanoes:

- Active: eruptions can be anytime and often. 

Volcán de Fuego, Guatemala
Volcán de Fuego, Guatemala

- Dormant: it has been a while since its last eruption, but it could happen at anytime. 

Mt. Fuji, Japan
Mt. Fuji, Japan

- Extinct: it hasn't erupted in a very long, long time (at least 25.000 years ago) so it probably won't erupt ever again.

Nevado Ojos del Salado, Argentina and Chile
Nevado Ojos del Salado, Argentina and Chile

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The type of magma in the earth creates four different types volcanoes:

Shield Volcano - flat

Shield volcanoes are volcanoes shaped like a bowl or shield in the middle with long gentle slopes made by basaltic lava flows. Basalt lava flows from these volcanoes are called flood basalts.

Examples include the volcanoes in Hawaii.

Kilauea, Hawaii
Kilauea, Hawaii

Composite or Strato volcano - tall and thin

If the magma is thick and sticky (like honey), the gas cannot escape, so it builds up and up until it explodes sending out huge clouds of burning rock and gas.

Composite volcanoes are steep-sided volcanoes composed of many layers of volcanic rocks, usually made from thick sticky lava, ash and rock debris (broken pieces).

Composite volcanoes are also known as strato-volcanoes. 

Examples include Mount Fuji in Japan and Mt. Etna in Italy.

Mt. Etna, Sicily (Italy)
Mt. Etna, Sicily (Italy)

Cinder cones

Cinder cones are circular or oval cones made up of small fragments of lava from a single vent that have been blown into the air, cooled and fallen around the vent. 

Examples include Kostal Cone in Canada and the Hverfjall in Iceland. 

Hverfjall, Iceland
Hverfjall, Iceland
Kostal Cone, Canada
Kostal Cone, Canada

Lava domes

Lava domes are formed when erupting lava is too thick to flow and makes a steep-sided mound as the lava piles up near the volcanic vent.

Examples include Mount Merapi in Indonesia and Novarupa in Alaska (USA).

Mt. Merapi, Indonesia
Mt. Merapi, Indonesia
Novarupa, Alaska
Novarupa, Alaska