Volcano Facts

A volcano is a rupture in the earth's surface in which hot magma, ash and gases escape from deep within the earth.

The word volcano comes from the word Vulcan after the Roman god of fire.

There are around 1,500 known volcanoes around the world, with the country of Indonesia being home to the world's largest number, see map below, of one hundred and twenty seven. This is because Indonesia sits on one of the world's subduction zones where two of the earth's major tectonic plates meet. In Indonesia's case it is the zone between the Eurasian Plate and the Indo-Australian Plate.

There are possibly around 10,000 volcanoes situated under the world's seas. These volcanoes are known as submarine volcanoes.

Volcanoes are generally found where the earth's tectonic plates converge or diverge or on oceanic islands.

Vulcan activity is generally classified as Active - Potentially active - Inactive / Dormant - Extinct.

Volcano types are classified as Composite / Strato - Shield - Cinder Cone - Spatter Cone - Complex / Compound -

Fissure vent.

The largest volcano in the world is the active shield volcano known as Mauna Loa, situated on the island of Hawaii, which stands 13,000 feet / 4,169 m above sea level with a possible further 16,000 feet below sea level.

The world's largest volcanic caldera, the cauldron shaped summit seen on some types of volcano, is situated on Mount Aso in Japan, measuring 25 km by 18km and with a circumference of 120 km.

The world's most active volcano is believed to be Stromboli in Italy, which vulcanologists believe has been continuously erupting, at various magnitudes, for between one and two thousand years.

There are around twenty volcanoes, of various magnitudes erupting around the world at any one given time.

Volcanic eruptions are measured by the Volcanic Explosivity Index (VEI ) which measures the volume of volcanic ejecta by per 1,000 cubic kilometres. The VEI classifies volcanoes from numbers 1 - 8, with 8 being the highest and most destructive.

The world's deadliest VEI 8 was caused by the Lake Toba Volcano on the island of Sumatra in Indonesia, which erupted between 69,000 and 77,000 years ago, which was followed by a six to ten year ' volcanic winter' which apparently left the planet with a population of just 10,000 people.

There have been a supposed eight VEI 8s around the world, all of which happened many thousands of years ago.

The deadliest volcanic episode in recent years, with a VEI of 7, was when Iceland's most active volcano, Grimsvotn, along with the neighbouring Laki Fissure Vent, between them spewed 14 square kilometers of basalt lava across Iceland's terrain and sent 120,000,000 long tons of sulfur dioxide and hydrofluoric acid into the atmosphere, over a period of eight months between June 1783 and February 1784.

The immediate destruction caused the deaths of 25% of Iceland's population and killed 50% of the country's livestock. The resultant ' volcanic winter ' (lack of light and drop in global temperature) resulted in illness and famine in northern Europe and droughts in Asia, which subsequently went on to cause the deaths of six million people worldwide.

Most of the world's islands and island groups are volcanic in origin, having been created from submarine volcanoes, hence the reason most of the world's volcanoes are situated on islands such as Hawaii, Indonesia and Japan.

Many larger islands have generally been formed from the summit of a submarine volcanoes, which are situated along a fault line or where two continental plates converge such as Iceland.

The world's largest volcanic island is the Island of Sumatra, situated in south east Asia, at 473,481 square kilometers in size.

The area where there is the world's highest instance of the world's volcanoes appears along an area of high tectonic activity known as the Pacific Ring of Fire - see map below - an area synonomous for it's high instance of earthquake activity.

For facts about earthquakes, visit our page - Earthquake Zones.

LIKE THIS? Show your friends - Tweet