A volcano is formed by an opening in the crust of the earth through which molten lava has forced its way to the surface. There are 169 active volcanoes in the United States. The majority are located in Alaska, while others can be found in the western half of the contiguous United States as well as in Hawaii.
If you are interested in what volcanoes are currently erupting or showing activity, the Smithsonian Institute offers a weekly volcano report.
- Smithsonian Institution, National Museum of Natural History: Smithsonian/USGS weekly volcanic activity report
- American Geosciences Institute: How many active volcanoes are there in the United States?
Volcanoes can often be found where tectonic plates meet. However, there are some, such as in Hawaii, that are formed more towards the center of the plates. Volcanoes usually form when weak areas in the crust move across magma chambers. Magma is hot molten materials including silica and rocks. Once it reaches the surface, it is called lava. This lava is what creates the shape of the volcano. As it spills onto the surface and cools, it adds to the terrain. Eventually, after multiple eruptions, a mountainous volcano is created.
There are different types of volcanoes. These are:
- cinder cones
- shield volcanoes
Dome volcanoes form over time and are created by a series of explosive eruptions. Calderas have very large openings caused by the collapse of the top of a volcano. Stratovolcanoes can be very steep and tall. They are formed by lava as well as volcanic rock and ash. Cinder cones are formed by gas that carries molten lava to the surface. Shield volcanoes can be quite tall but are not usually as steep as stratovolcanoes. They are usually formed almost exclusively by lava flow.
Fun Facts About Volcanoes
There is a lot that you can learn about volcanoes:
- Approximately eighty percent of eruptions are deep-sea eruptions.
- Ocean life flourishes in the warmth near deep-sea volcano vents.
- Fresh lava is very hot. It can be between 1,300 and 2,200 degrees Fahrenheit.
- Super volcanoes do not actually form a mountain. Instead, they create indentations that often become filled by lakes.
- Volcanoes are not limited only to earth. They can be observed on other planets as well.
- Lightening may occur after an eruption if there is an ash cloud present.
- Erupting volcanoes have caused earthquakes, floods, tsunamis, and rockslides.
- Volcanic eruptions can send ash as high as 17 miles up into the atmosphere.
- The majority of volcanoes are located in the Ring of Fire around the Pacific Ocean.
Volcanoes in the United States
Two of the most famous volcanoes in the United States are Yellowstone and Kilauea.
Yellowstone park is in Wyoming as well as Montana and Idaho. The park covers nearly 3,500 square miles, while the volcano itself is estimated to be approximately 34 by 44 miles wide. This super volcano is located on a hot spot that has created significant super-eruptions over millions of years. The three eruptions that were large enough to be classified as super-eruptions occurred 2.1 million, 1.3 million, and 630,000 years ago. Even today, hot magma still flows beneath the park. Active geysers, including the famous Old Faithful geyser, can be observed in the park.
Kilauea is a shield volcano and it is the most active volcano on the planet. It can be found on the Big Island of Hawaii. Because it is so active, its Hawaiian name translated to "spewing" or "much spreading." It has a 2-mile by 2-mile wide summit caldera, although it does not have the traditional mountainous features or height that is commonly associated with volcanoes.
In addition to these two famous volcanoes, there are others with features worth mentioning:
- Mauna Loa, which can also be found on the Big Island in Hawaii, is the highest and largest volcano on the planet.
- Mount St. Helens is an active stratovolcano located in the state of Washington. Its eruption in 1980 was the most destructive volcanic occurrence in the history of the United States.
- Mount Rainier, also located in the state of Washington, is the most glaciated peak in the contiguous United States.
- Mount Novarupta, in Alaska, had an eruption in 1912 that was the largest one ever recorded.
There are many more volcanoes to be explored in the United States. They often make great hiking and skiing locations as well as places to view wildlife and explore the great outdoors. Before heading out to any volcano, make sure to check for recent volcanic activity or warnings in the area.
- Montana State University: An overview of Yellowstone geologic history
- The Public Broadcasting Service: Kilauea, Mountain of fire
- Alaska Kids: Volcanoes
Volcanoes can make excellent science project topics and the set up for the experiments can be fun as well. The explosions are probably the best part. Volcano explosions can be simulated with a variety of materials and chemical interactions. Below are links to the plans for three fun experiments that can be tried at home or in the classroom:
- Use Mentos and soda to simulate a volcanic eruption: National Association of Geoscience Teachers
- This kitchen-ingredients volcano can be made with dish soap, baking soda, and vinegar: Science Fun
- Make your own "lava" with vegetable oil and salt: Greensboro Science Center
Additional Resources for Kids
Are you ready to learn more about volcanoes? There is plenty to explore. Learn all there is to know about magma, lava, domes, super volcanoes, tectonic activity, and more!
- Oregon State University talks about some of the positive things that come from volcanoes: What are some good things that volcanoes do?
- Penn State talks about how long volcanic eruptions can last for: How long does an eruption last?
- The USGS Earthquake Hazards Program has an array of information to check out: Earthquakes for kids
- California State University Northridge has some information on the formation of volcanoes: How do volcanoes form?
- Try to solve the new Formula Cube! It works exactly like a Rubik's Cube but it is only $2, from China. Learn to solve it with the tutorial on rubiksplace.com or use the solver to calculate the solution in a few steps.