There are volcanoes all over the world. Usually, we think of volcanoes as mountain-like structures on land, but there are volcanoes under our ocean as well, and even on other planets. Volcanoes can create land, like the Hawaiian Islands, or destroy cities and villages like Mount Vesuvius in Italy. They are definitely among the most dynamic and interesting natural wonders on Earth.
What is a Volcano?
Flordia International University defines a volcano as an opening in the earth’s crust where molten material under the crust is propelled through the surface. Volcanoes have a magma chamber where molten rock and other materials collect that will be expelled during an eruption. The National Park Service tells us that the word “volcano” comes from the Roman god of fire, Vulcan.
Molten materials inside the chamber are called magma. It can consist of rock, silica, gas, and other materials. The United States Geological Survey says that once magma is expelled during an eruption, it is then called lava. After numerous eruptions, the cooling lava eventually builds up the height of the volcano, forming a mountain shape or land around it.
How is a Volcano Formed?
Volcanoes are formed when land masses with weak points or fissures travel over a magma chamber filled with contents that are under significantly high pressure. Oregon State University states that volcanoes are a way for the Earth to cool off and release heat and pressure from within.
There are various areas that volcanoes can form; a subduction zone, a spreading center between two tectonic plates, and in an intraplate area. San Diego State University explains that subduction zone volcanos occur where one continental plate dives below another and creates a volcanic arc. The University of Illinois explains that plates that pull away from each other in a spreading center cause molten material to fill voids in the cracks and form volcanoes. Intraplate Volcanism is a volcano that is above hotspots not found on plate boundaries but in the middle of tectonic plates, such as the Hawaiian hotspot.
What are the Different Types of Volcanoes
There are five major types of volcanoes, as shown on the Volcano Information Center; stratovolcanoes, cinder cones, shield volcanoes, domes, and calderas
Stratovolcanoes are composed of layers of lava with sand or gravel-like volcanic rock called cinders or volcanic ash. These types of volcanoes are steeper than others and can reach up to 10,000 feet high. An example of a stratovolcano is Mayon in the Philippines. You can read about Mayon at the Library of Congress.
Shield volcanoes are usually hundreds of miles across and can reach 10,000 feet high. These volcanoes have gentler slopes with slightly steeper lower slopes. They are also almost completely composed of thin lava flows built up around a central vent. Mauna Loa on the Big Island of Hawaii is a great example of a shield volcano. You can learn more about Mauna Loa volcano at the Hawaii University of Manoa.
Cinder cones develop when streaming gas carries liquid lava blobs into the atmosphere that fall back to Earth around the vent. If gas pressure drops inside the cinder cone, a lava flow will break through the base of the cone. Cinder cones can develop into one cone or into several cones in small or large groups. You can find a cinder cone volcano in Mexico, called Paricutin Volcano, and can read more about it at the University of North Texas.
Lava Domes form from slow flowing, highly viscous silica-like magma. Most domes will be on the small side but they can also get quite large. Lava Domes usually start with explosive eruptions which gradually dissipate as the gas content decreases. These types of volcanoes are also known to collapse on themselves, as did Mount Unzen in Japan. Collapsing causes a sizable and destructive pyroclastic cloud.
Calderas are circular or oblong depressions formed by a collapsed volcano. Once collapsed, their opening is much larger than the original vent. These sorts of major eruptions and collapses are quite rare, and happen once every 100,000 years or so. There are many calderas within California and New Mexico.
Fun Facts About Volcanoes
While the thought of being in a volcanic eruption can be scary, volcanoes are one of the Earth’s most dynamic objects. There is so much we can learn from studying volcanoes.
The National Ocean and Atmospheric Administration says that 80 percent of all volcanic eruptions occur in the deep ocean. The deep-sea volcano, West Mata, is believed to be among the hottest erupting volcanoes on Earth. Deep-sea volcanoes can create an amazing and thriving ecosystem. The National Science Foundation explains how life can live next to thermal vents. The water is exceedingly hot, but creatures such as shrimp, crabs, and tube worms can live and thrive near these vents.
According to Do Something, the danger area of a volcano is roughly a 20-mile radius. Also, within the ash clouds after an eruption, lighting can also be observed. This is caused by the friction of ash rushing to the surface.
Supervolcanoes are characterized by having a large magma chamber. Their eruptions are so large that no mountain exists. However, after a major eruption, the area is low and lake-filled. Supervolcano eruptions are rare. The last one occurred in Indonesia about 74,000 years ago. Yellowstone is an example of a dormant supervolcano. Yellowstone National Park lies within the Yellowstone Caldera which still has hot magma underneath. This also explains the large amount of geysers and hot springs in the area. If you are interested in the Yellowstone supervolcano, you can read more at the Montana State University website.
Volcanoes also occur in other parts of our solar system, according to NASA. Venus and Mars are covered with extinct volcanoes, while the moons of Jupiter, Saturn, and Neptune have active volcanoes. You can also view videos of those eruptions at the NASA website. The University of Wisconsin-Green Bay is also a great place for information, you can visit them at: Top 10 earthquakes and volcanic eruptions.
Kilauea is the most active volcano on Earth and is located on the Big Island of Hawaii. Mauna Loa, also located on the Big Island, is the tallest volcano on Earth from base to summit. PBS has an amazing video story about the Kilauea volcano. The volcano is said to be home to the goddess Pele, and sometimes people capture her imagine in the lava. You can also safely observe the volcano up close at the National Volcanoes Park in Hawaii.
Indonesia has several famous volcanoes that are still active today. Western Washington University shows that a volcano in Indonesia, called Tambora, had one of the largest eruptions in history in April 1815. It was large enough to cause worldwide temperature drops.
While it was not the most destructive eruption, Mount. Vesuvius has preserved an Italian way of life since 79 A.D. The eruption was a two-day event and devastated the resort towns of Pompeii and Herculaneum. You can read more about Mount Vesuvius and Pompeii at Windows to the Universe.
To learn more about volcano history, visit the University of California Berkley: Mount Saint Helens.
Online Resources for Kids
Weather for Kids has some fun facts about volcanoes: Facts about volcanoes.
Ready discusses how to stay safe during and after a volcanic eruption: Volcanoes.
One Geology walks readers through the process of volcano formation and eruption: Volcanoes.
Alaska Kids talks about the unique volcanoes in their state: Alaska volcanoes.
Lesson Plans for Parents and Educators
The National Association of Geoscience Teachers offers plans for creating simple volcano experiments: Mentos and soda eruptions
Exploratorium has the directions for making a salt volcano in the classroom or at home: Salt volcano
Saint Edwards University offers a first-grade lesson plan on volcanoes: Volcanoes lesson plan for 1st graders
The Ohio State University has plenty of fun and educational activities: Hands-on science and literacy activities about erosion, volcanoes, and earthquakes.