1. The term “volcano” is from the Latin Volcanus or Vulcan, the Roman god of fire. The Romans first used the term to describe Mt. Etna, a volcanic mountain they believed was the forge of Vulcan.^b
2. The ancient Greeks thought that the god of Fire, Hephaestus, lived beneath Mt. Etna. The Titan god Prometheus is said to have stolen fire from Hephaestus’s volcano to give to humans.^b
3. Hundreds of years ago, the Aztecs of Mexico and the people of Nicaragua believed gods lived in lava lakes. They would sacrifice beautiful young girls to these powerful gods.^b
4. Well into the Middle Ages, many believed volcanoes were entrances into the fiery underworld.^b
5. During the past 400 years, nearly a quarter of a million people have been killed as a direct result of volcanic eruptions. Indirect aftereffects such as famine, climate change, and disease most likely have tripled that number.^e
6. Many scientists believe that all the water on the earth was originally vented into the atmosphere by volcanoes.^a

The unique Maelo bird incubates its eggs in warm volcanic soil

7. A species of bird called a maleo uses heat given out by warm volcanic sand to incubate its large eggs. When the chicks hatch, they burrow their way to the surface of the sand.^c
8. The most dangerous volcano today is Popocatépetl, nicknamed El Popo, which is just 33 miles from Mexico City. El Popo is still active, sending thousands of tons of gas and ash into the air each year.^d
9. The myth of the lost city of Atlantis sinking beneath the waves may be based on the Greek island of Santorini, of which portions collapsed into the sea after a large volcanic eruption during the Bronze Age.^b
10. Volcanologists use a special electric thermometer called a “thermocouple” to take a volcano’s temperature. Lava is so hot that a glass thermometer would melt.^a
11. There are no active volcanoes in Australia because it sits in the middle of a tectonic plate.^c
12. Highly volcanic areas have some of the most fertile farmland in the world. Volcanic eruptions bring nutrients such as potassium and phosphorus to the Earth’s soil. The weathering of volcanic rocks also releases nutrients.^c
13. “Lava” derives from the Latin lavara, meaning “to wash,” and is magma that has erupted at the surface.^e Lava can flow up to speeds of 62 miles per hour.^d
14. The material ejected from a volcano is called “pyroclastic flow” from the Greek pyro (fire) and I (broken). It includes small fragments of rock, frothy pumice, and large boulders. Pyroclastic flow can reach temperatures of 212° F and can rocket down the side of a mountain at 155 m.p.h.^d
15. Volcanoes form through subduction (when two tectonic plates smash against each other), mid-oceanic rift (when two plates drift apart), or in a hot spot (a weak spot in one of Earth’s plates).^g

Surtsey, one of Earth's newest islands, was dramatically formed in 1963 by underwater volcanic eruptions

16. In 1963, an undersea volcano created the newest land mass on Earth, Surtsey Island, which lies off the southwest coast of Iceland. Today Surtsey is about 1 sq. mile and is named after Surt, a fire giant from Norse mythology.^b
17. The worst volcanic disaster of the twentieth century is considered to be the eruption of Mt. Pelée in 1902 on the island of Martinique in the Caribbean which killed 30,121 people. Only two people survived: a shoemaker living on the edge of the island and a prisoner who had been locked in a dungeon cell with thick stone walls.^h
18. There are approximately 1,500 active volcanoes, not counting undersea volcanoes. Of these, only about 20-30 erupt in any one year.^g
19. Volcanologists measure the size of an eruption with the Volcanic Explosivity Index (VEI), with 0 being the weakest and 8 the strongest. Eight is usually reserved for super eruptions, popularly called “supervolcanoes.”^a
20. The Lake Toba supervolcanic eruption nearly 75,000 years ago in Indonesia plunged earth into a volcanic winter (known as the Millennium Ice Age) and was responsible for the formation of sulfuric acid in the atmosphere.^d

Mount St. Helens is North America's most active volcano

21. The eruption of Mount St. Helens on May 18, 1980 had 500 times the power of an atomic bomb. Geologists considered this a moderate eruption.^h
22. The Pacific Ring of Fire is the boundary of the large Pacific plate which is slowly subducting under or grinding past other plates. Most of the world’s biggest volcanoes are concentrated here.^b
23. In A.D. 79, Vesuvius erupted violently, devastating the towns of Pompeii and Herculaneum. Eyewitness accounts of the time, recent excavations, and the preserved remains tell the horrific story of the eruption.^h
24. In 1660, the people of Naples were shocked to find what looked like little black crosses raining down on them. While they thought it was proof that St. Januarius was looking out for them, the crosses were really twin pyroxene crystals which Mt. Vesuvius spewed out of its crater. Vesuvius last erupted in 1944.^c
25. New ocean floor is created when two oceanic plates move apart and magma bubbles up to fill the rift. This is called a rift volcano. Through this process, the Atlantic Ocean is widening by 2 cm. per year, and the East Pacific Rise is widening by 20 cm. a year. In 10 million years, the East Pacific Rise will be 1,240 miles wider.^a
26. Pele is the Hawaiian goddess of fire and volcanoes and was thought to live in the crater of the Kilauea volcano on Hawaii. She is said to have a terrible temper and will throw lava at anyone who angers her. Some people have been known to send back lava samples they have taken from the Hawaiian Volcanoes National Park because of the bad luck they associate with Pele.^h
27. The three main types of volcano shapes are shield, cinder cone, and stratovolcano. Stratovolcanoes, also called composite volcanoes, are the most common type of volcanoes and often have symmetrical steep slopes. Classic examples include Mount Rainer in Washington State and Mount Fuji in Japan.^a
28. When the top of a volcano top collapses, it forms a caldera, which is Spanish for “kettle.” The largest caldera is the La Garita Caldera in Colorado which was formed 26-28 million years ago and was one of the largest eruptions—if not the largest—on Earth.^g
29. About 20% of all volcanoes are under water.^a

The black sand beaches in Iceland and Hawaii are formed by grains of black volcanic glass

30. Some volcanic islands such as Iceland and Hawaii have black beaches. Their sand is made from basalt, an igneous rock formed when lava cools and has been broken down into sand particles.^b
31. More than 300 million people (nearly 1 in 20) live in the shadow of active volcanoes, including Mount Vesuvius in Italy, Mount Rainer in the U.S., and Popocatepetl in Mexico.^h
32. In some volcanic areas such as Iceland, heat energy from magma can be used to warm water and run power plants. This type of energy is called geothermal (earth heat) energy.^b
33. Edvard Munch’s famous painting The Scream is thought to show a volcanic sunset caused by the massive eruption of Krakatau in Indonesia in 1883. The blood-red sunset could be seen as far away as Norway, where Munch lived.^h
34. When Paricutin in Mexico erupted from 1943-1952, no one was killed by ash, rocks, lava, gases, or mud flows, though three people died from being struck by volcanic lightening. Though there were periods of violent explosions, Paricutin mainly dishcharged quiet flows of lava during its continous nine year eruption.^b
35. In 1943, a Mexican farmer named Dionisio Pulido witnessed the birth of a volcano in his cornfield about 329 kilometers west of Mexico City. It started as a slight depression in his field and soon became a fissure that emitted smoke and hissing noises. During the next nine years, the volcano Paricutin had grown to an elevation of 2,272 meters and its voluminous lava flows had destroyed several towns.^h
36. The 1815, volcano Tambora in Indonesia was the greatest volcanic eruption observed by humans and killed over 70,000 people. Effects were felt as far as Europe and North America, including prolonged inclement weather which resulted in food riots and the worst famine in the nineteenth century.^h
37. Tambora’s 1815 massive eruption and its devastating effects are said to have inspired Lord Byron’s gloomy poem “Darkness” (1816) and Mary Shelley’s immortal novel Frankenstein (1818).^h
38. Yellowstone National Park in Wyoming sits on the site of an ancient supervoclano. It erupted around 2 million years ago, 1.3 million years ago, and 640,000 years ago. If it follows the same pattern, another eruption is due any time now.^c
39. Japan has 10% of the world’s active volcanoes.^d
40. Iceland is made up almost entirely of volcanic rocks like those found on the ocean floor. It gradually built up above sea level through intense and prolonged eruptions.^b
41. In August 1986, a cloud mixture of carbon dioxide and water rose from Lake Nyos, a crater lake in Cameroon (western Africa). The heavy gas cloud flowed downhill and gathered in the valleys, asphyxiating 1,700 people and 3,500 livestock living in the villages below.^d
42. An acid lake in the crater of Kawah-Idjen in Indonesia absorbs gases rising from the volcano, creating a lake so toxic it can burn through human flesh in minutes.^d
43. Magma is Latin for “dregs of ointment,” which derives from the Proto Indo-European mag meaning “kneading.” The term “magma” in its geological sense as molten rock was first used in 1865.^e
44. The earliest known picture of a volcano is the nearly 8,000-year-old wall painting of an eruption of Hasan Dag volcano in Turkey. The houses of a town, Çatalhöyük, can be seen at the mountain’s base.^b
45. In Japan, “baths” in warm volcanic sand are believed to cure many illnesses.^h

The largest volcano in our solar system is Olympus Mons on Mars

46. The largest volcano found in the solar system is Olympus Mons on Mars, though it is now extinct.^a
47. Venus may have at one time produced more volcanoes than any other planet in our solar system, though they are all now extinct.^a
48. While no other planet besides Earth shows active volcanoes, Io, one of Jupiter’s moons, shows volcanoes that are erupting.^a
49. The 1883 eruption of Krakatau in Indonesia is thought to have released 200 megatons of energy, the equivalent of 15,000 nuclear bombs. Even though the island was uninhabited, the eruption killed 36,000 people as the result of burning ash showers and huge tsunamis. It generated the loudest sound historically reported.^d
50. The most lava ever recorded from a single eruption was the 1783 Laki eruption in Iceland. Though there was no single big explosion, this eruption killed one fourth of Iceland’s population by producing poisonous gases and clouds of ash that resulted in widespread crop failure and starvation.^d
51. In January 2009, scientists from the Alaska volcano observatory warned that Mt. Redoubt, a peak just 100 miles southwest of Anchorage, could erupt anytime. Mt Redoubt last erupted in 1989, shooting ash high into the jetstream, causing engine failure in a KLM jet carrying 231 passengers. The plane dropped more than 2 miles before the crew could restart the engines.^f

-- Posted January 30, 2009. Updated September 23, 2010.

References

^b Claybourne, Anna. 2007. Volcanoes. Boston, MA: Kingfisher Publications.

^c Gates, Alexander E, and David Ritchie. 2007. Encyclopedia of Earthquakes and Volcanoes. 3rd Ed. New York, NY: Infobase Publishing.

^d McGuire, Bill. 2002. Raging Planet: Earthquakes, Volcanoes, and the Tectonic Threat to Life on Earth. Hauppage, NY: Quarto Inc.

^e Etymology Online. “Online Etymological Dictionary.” Accessed: January 20, 2009.

^f Joling, Dan. "Alaskans Brace for Redoubt Volcano Eruption." Yahoo News. January 30, 2009. Accessed: January 30, 2009.

^g Rothery, David A. 2007. Volcanoes, Earthquakes, and Tsunamis. Blacklick, OH: McGraw-Hill.