Athanasius Kircher created the first known map of the distribution of volcanoes in 1665. Sometimes called the last Renaissance man, he devoted his life to research. Investigating Vesuvius, he had himself lowered into its crater to measure its interior dimensions. He had some theories, but had no idea what caused volcanoes.
Modern geologists say the earth’s surface is composed of moving plates, which may move apart, or slowly consume one another. Volcanoes appear where one plate of the earth’s crust slides under another in subduction, or where two plates diverge. Subduction melts living rock, and the result is active volcanoes. Magma wells up where plates separate, and this too causes volcanism.
Therefore, any guide to active volcanoes must lay a special emphasis on the plate edges where volcanoes cluster, in regions like the Ring of Fire. Volcanoes stand near other plate boundaries too, however.
Yet many volcanoes erupt in unexpected areas too, partly because the borders of tectonic plates are not regular. The world’s best-known active volcanoes:
Vesuvius, Etna, and Stromboli are the famous volcanoes of Italy. Vesuvius, the only active volcano in mainland Europe, buried Pompeii and Herculaneum eighty feet deep. The sudden eruption caught people in mid-stride as they turned to flee, and preserved an untouched record of their civilization for nearly two millennia.
Etna, on the island of Sicily, is almost constantly active, and twice as tall as Vesuvius. Stromboli is an island volcano north of Sicily, one of a chain of volcanic islands called the Aeolians.
Slightly south of the Italian volcanoes runs the border between the Eurasian plate and the African plate. As the African plate is drawn under the Eurasian, water from the subducted plate rises into the rock above it and generates magma. The magma rises, and if it reaches the surface, it produces volcanic eruptions.
Iceland, the Azores, and other Atlantic islands are volcanic. Iceland harnesses the geothermal power of the magma beneath it to heat its homes; overall, the country benefits from volcanism. However, Icelandic volcanoes can also cause disruption, as the 2010 Eyjafjallajökull eruption did.
The foggy Azores are immensely tall volcanic peaks that arise in mid ocean. They are located where three plates adjoin, and have had 28 volcanic events in the nearly 600 years since colonization.
Tristan de Cunha in the South Atlantic may be the most remote permanently inhabited place in the world. The main island in the group sits on the mid-Atlantic Ridge, dominated by a tall volcano.
The mid-Atlantic ridge is a divergent tectonic plate boundary, where lava wells up as plates move apart, and new plate material is constantly created.
Africa and the Middle East
Kilimanjaro is the highest freestanding mountain in the world and a volcano, though its fires are damped for now. One of many volcanoes of the East Africa Rift zone, it indicates that someday an ocean will roll between two plates that are presently part of Africa. The volcanoes of the East Africa Rift continue up the coast of Saudi Arabia, though none has erupted there in hundreds of years.
Mount Fuji, graceful symbol of Japan, is an active stratovolcano, built up of layers of lava, pumice and ash.
North of Japan, the Kamchatka Peninsula has 29 active volcanoes, and many volcanic features. South of Japan, the Philippines also have many volcanoes, including deadly Mt. Pinatubo.
Chains of volcanoes curve east-west through Indonesia, and dot the continent of Asia, where plate edges butt together or moving plates drift over a hot spot, an upwelling of magma.
Hawaii and the South Pacific
Hawaiian volcanoes are slowly extending the island chain to the southeast, as the older northwestern islands sink and erode away.
In the South Pacific, a line of volcanoes extends north from New Zealand, where the Kermadec Trench and the Tonga Trench mark underwater subduction zones, making nearby islands volcanically active.
Pitcairn, famous as the refuge of the Bounty mutineers, and Easter Island, famous for its statues, are both volcanic islands, but their volcanoes are inactive.
The Aleutians, which connect Alaska to Russia, hold 57 volcanoes. They lie where the Pacific and North American plates abut. Mainland Alaska has many volcanoes too, including Mt. Spur and Mt. Redoubt. The volcanoes of Canada are in unpopulated areas, and relatively lightly monitored.
The Cascade Range, which runs from Washington to California, holds Mt. St. Helens, Crater Lake, extinct but beautiful, Mt. Shasta, and magnificent Mt. Lassen. East of the Cascades many parts of the western U.S. show potential for eruption, such as the Long Valley Caldera near the California ski town of Mammoth. West of the North American coast, seamounts like Axial and Coaxial show volcanic activity, and support colonies of strange underwater life.
Mexico holds legendary Popocatepetl, Iztaccihuatl and many more.
The Central American Volcanic Arc holds many active volcanoes, and is caused by a subduction zone. East of Central America, Mt. Pelee destroyed the Caribbean city of Pierre and killed 28,000 people in 1902. Soufriere Hills destroyed much of the capital of Monserrat Island in 1995, but the populace evacuated in time.
Clusters of high volcanoes stand in the Andes, fed by subduction. Offshore in the Galapagos Islands is a volcano named Darwin. Robinson Crusoe Island is built of old shield volcanoes, and a new volcanic island may be forming to the north of it.
Volcanoes stand on every continent and in every ocean. They come to life where tectonic plates come together or part, and fade as their fiery sources of liquid rock cool.
Rising Fire by John Calderazzo
Vesuvius: A Biography by Alwyn Scarth
Volcanoes by Maurice Krafft