What is a Stratovolcano?

A stratovolcano, also known as a composite volcano, is a tall, cone-shaped volcano built up of many layers of hardened lava, tephra, pumice and ash. They are the most common type of volcano in the world and are typically found near plate boundaries where tectonic activity is high. The classic example of a stratovolcano is Mount Fuji in Japan.

Stratovolcanoes are characterized by their steep sides and large size; they can grow to be over 12 kilometres (7.5 miles) tall! The tallest active stratovolcano in the world is Mauna Loa on the island of Hawaii which stands at almost 10 kilometres (6 miles) tall. Stratovolcanoes are different from shield volcanoes which have much flatter slopes due to their lower viscosity lava flows.

The inside of a stratovolcano consists of a central conduit or chimney that extends all the way to the surface. This conduit is surrounded by walls of solidified lava called magma chambers. When eruption conditions are right, magma will rise up through the conduit and erupt from the summit crater or from fissures on the flanks of the volcano.

The eruptions from stratovolcanoes can be very explosive due to the highly viscous nature of their magmas but they can also produce stunningly beautiful lava flows that slowly make their way down the side of the mountain. Some well-known examples of stratovolcanoes with particularly spectacular lava flows include Mount Etna in Italy and Kilauea in Hawaii.

While stratovolcanoes can be found all over the world, some of the most active and dangerous ones are located along the so-called “Ring of Fire” which is a horseshoe-shaped region in the Pacific Ocean where a large number of earthquakes and volcanic eruptions occur. Some famous stratovolcanoes located along the Ring of Fire include Mount St. Helens in Washington state, USA, Mount Pinatubo in the Philippines and Mount Fuji in Japan.