ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel
  • »
  • Education and Science»
  • Geography, Nature & Weather

How Volcanoes Form & Erupt

Updated on March 7, 2017
Augustine Volcano in Alaska
Augustine Volcano in Alaska | Source

What is a volcano? By definition, it's an opening in the earth's crust where hot magma (lava), gases, and ash can escape from deep below the planet's surface.

What makes volcanoes really cool is that they can create new landmasses from the cooling magma.

The entire Hawaiian island chain was created from underwater volcanic hot spots that expel magma. After the magma cooled and hardened, it formed land. Vegetation started growing on the islands and animals started making this newly created tropical paradise their home. However, volcanoes don't just make island chains overnight. Hawaii is a work-in-progress and is over 28 million years in the making!

Lava flowing into the ocean at Hawaii Volcanoes National Park
Lava flowing into the ocean at Hawaii Volcanoes National Park | Source

Volcanoes are generally found where tectonic plates meet. Volcanoes on the mid-Atlantic Ridge (Iceland is on the mid-Atlantic ridge) are formed from tectonic plates that are pulling apart (or divergent plates.) Convergent plates (or plates that are pushing together) are guilty of creating the Pacific Ring of Fire.

The Ring of Fire is huge! It stretches from New Zealand on up through Indonesia, the Philippines, Japan, on to Russia and then east to Alaska. From Alaska down the western coast of Canada and the US. From there, the Ring of Fire extends all the way down the western coast of Mexico on through Central and South America until it reaches the southern tip of South America.

The Ring of Fire is known for some infamous volcanoes such as Krakatoa in Indonesia, Mt. Pinatubo in the Philippines, Mt Fuji in Japan, and Mount St. Helens in the State of Washington.

Llaima Volcano in Chile
Llaima Volcano in Chile | Source

What's a Volcanic Hotspot?

A volcanic hot spot is an area under the earth's crust that stays fixed in place as tectonic plates move over them. As a plate moves over a hot spot, new volcanoes are created. After a while, these volcanoes become permanently dormant and are replaced by a new volcano elsewhere on the plate (where the hot spot is.)

The Hawaiian islands were created by a volcanic hot spot. Over time, as the plates move, volcanoes will add more islands to the Hawaiian island chain.

A lava flow in Hawaii
A lava flow in Hawaii | Source

Volcanic Eruptions Throughout History

Volcano
Year
Death Toll
Mt. Tambora, Indonesia
April 1816
92,000 + 100,000 (famine)
Mt. Pelee, West Indies
April/May 1902
40,000
Mt. Krakatoa, Indonesia
August 1883
36,000 (tsunami)
Nevado del Ruiz, Columbia
November 1985
23,000 (mudslide)
Mt. Unzen, Japan
1792
~14,000 (tsunami)
Mt. Vesuvius, Italy
79
10,000 (Pompeii)
Laki, Iceland
June 1783 - February 1784
9300 (famine)
Mt. Kelut, Indonesia
May 1919
5100 (mudslide)
Volcán de Agua in Sacatepéquez, Guatemala
Volcán de Agua in Sacatepéquez, Guatemala | Source

The Different Types of Volcanoes

The very word "volcano" brings forth images of a cone-shaped mountain, perhaps with lava spewing out. Sometimes volcanoes have multiple cones which are caused by vents that form on the surface. Puʻu ʻŌʻō is a cone formed from a vent on Hawaii's Kīlauea volcano.

Mount Shasta in Northern California
Mount Shasta in Northern California | Source

Some volcanoes aren't cone-shaped at all! One type, called fissure vents, don't have explosive activity but are simply flat channels that lava slowly flows along. Many cone-shaped volcanoes also have fissure vents.

Very broad volcanoes, called shield volcanoes, don't erupt as violently as their cone-shaped counterparts, but the lava is a much lower viscosity than lava from fissure vents. This leads to the very broad shield-like shape of these volcanoes.

A lava dome is often found in the crater of a previous eruption and look kind of like a mini-volcano inside of a much larger volcano. The eruption from this type of volcano is usually very violent, but the lava has a very high viscosity so it doesn't flow very far. Mount St. Helens is a perfect example of a lava dome.

When highly viscous lava is forced up through a volcano, it can form what is called a cryptodome, which is essentially a bulge. A cryptodome formed on Mount St. Helens shortly before it erupted in 1980.

Colima Volcano in Mexico is one of the most active volcanoes in North America
Colima Volcano in Mexico is one of the most active volcanoes in North America | Source

Volcano Facts

  • When Krakatoa erupted in 1883, the explosion was heard nearly 3000 miles away. It was the loudest sound heard in modern history.
  • Pumice, a volcanic rock, is the only rock that can float in water.
  • The 1991 eruption of Mount Pinatubo released 22 million tons of sulfur dioxide lowering the global temperature by 0.5 degrees Celsius.
  • Mauna Loa, a Hawaiian volcano is actually taller (from base to top) than Mount Everest, but Everest is higher in elevation.

Source

Comments

    0 of 8192 characters used
    Post Comment

    • Marina Lazarevic profile image

      Marina 5 years ago from San Francisco, CA

      Seriously awesome photo selection! This is so much more informative than my go-to resource on volcanos, Dante's Peak.

    • wba108@yahoo.com profile image

      wba108@yahoo.com 5 years ago from upstate, NY

      Terrifc Hub! Volcanoes are the greatest force in nature with thier eruption being sometimes a hundred times the power of a nuclear bomb! It makes make stand back in awe of God's creation as a reflection of his own awesome power and wonder!

    • rob_allen profile image

      rob_allen 5 years ago from MNL, PH

      Such a well researched hub. I remember back in Grade school, my report was all about volcanoes and how they were formed. I would definitely recommend this hub to my niece who is on grade school right now. She will need these information in her science class. :)

      Mt.Pinatubo is just near my Grandma's place. When it erupted, she told me that it was like night during the day and everything was covered by ashes.

    • Marcy Goodfleisch profile image

      Marcy Goodfleisch 5 years ago from Planet Earth

      Geological formations and anything about the Earth's movement fascinates me. Volcanos and earthquakes are two phenomena, in particular, that I like to learn about. I enjoyed this hub - thanks for explaining some of the mysteries of our planet! Voted up, interesting and useful.

    • freelanceauthor profile image

      freelanceauthor 5 years ago

      You've done your research well, particularly on the dates and casualties of major eruptions. Great hub. Voted up

    • RealHousewife profile image

      Kelly Umphenour 5 years ago from St. Louis, MO

      Awesome Melbel! Volcanoes are so interesting. I loved the info and wish I could see that Ring of Fire from a helicopter! I am going to bookmark this and let my girls read it when they get home from school. They will also love the pictures and information. Science fair is going on - so you know there is lots of volcano talk going on around here right now - I bet at least one child makes one!

    • Greensleeves Hubs profile image

      Greensleeves Hubs 5 years ago from Essex, UK

      Useful reading melbel for anyone who wants to learn about one of the most fascinating - and violent - of all nature's forces.

      I have seen the Arenal volcano which erupts almost daily (though I only saw a thin trickle of glowing lava at night, which faded after a few seconds) and I've been to Pompeii.

      Volcanoes should hold interest for everyone as the most visible sign of the Earth's active geology, as a devastating influence on human life, and as a thing of beauty.

      Thanks. Voted accordingly. Alun.

    • Stephanie Henkel profile image

      Stephanie Henkel 5 years ago from USA

      Very interesting and informative hub! I love your selection of photographs, too, as they show volcanos in all stages from erupting to dormant. Very nice1 Voted up!

    Click to Rate This Article