Shield Volcano Facts

Shield Volcano Facts
A shield volcano is usually built up from highly fluid magma flows, which results in a volcano with a low profile that is spread over a large area, similar to the shield of a warrior if it were lying on the ground. The width of a shield volcano is usually 20 times its height, on average, but that doesn't mean that they do not reach high altitudes. Shield volcanoes can form from one single long-term eruption or over the course of several eruptions. Many of the shield volcanoes on earth are located in Hawaii, including Hawaii's volcano Mauna Loa which is considered to be the second largest volcano on earth, next to Tamu Massif in the Pacific Ocean.
Interesting Shield Volcano Facts:
The way that a volcano gets its shape is determined by the lava. Shield volcanoes have low viscosity lava, described as being basaltic.
Shield volcanoes' low viscosity lava means that the lava is more liquid and flows more quickly than thick lava. Therefore it can spread further, building up thin layers that continue to accumulate and create the shield volcano's shape.
Shield volcanoes have lava tubes which are a type of cave-like structure made up of hardening lava that forms an insulating layer that allows the lava underneath to travel further.
A lava tube in Hawaii Volcanoes National Park called the Thurston Lava Tube, is a tourist attraction. It looks like a long tunnel.
When the lava from a shield volcano reaches water, the temperature of the lava meeting the water causes an explosive eruption of steam, ash, and sometimes rock. This type of eruption is called hydrovolcanic.
Mauna Loa in Hawaii is the world's largest subaerial (located on the earth's surface) volcano and the second largest overall volcano, at 13,680 feet above sea level, reaching another 8 miles below the surface of the water into the earth's crust. It is also the largest shield volcano on earth by volume.
Mauna Loa makes up more than 50% of Hawaii's surface area.
Mauna Kea is a shield volcano in Hawaii that is 120 feet taller than Mauna Loa, but is not as big overall. Mauna Kea is 4000 feet taller than Mount Everest.
Iceland has several shield volcanoes. The shield volcanoes there are smaller than in other parts of the world and are only 5,000 to 10,000 years old on average.
The Galapagos Islands are home to many shield volcanoes. The shield volcanoes there are much older than in Iceland, and are believed to be between 700,000 and 4.2 million years old. Fernandina Island is one of several shield volcano islands in the Galapagos Islands.
Shield volcanoes can be found in New Zealand (Rangitoto), United States (Belknap volcano and Newberry volcano).
Ethiopia, in Africa, has an active shield volcano called Erta Ale. Erta Ale has a lava lake in its caldera (crater). Africa has several shield volcanoes.
Shield volcanoes exist on other planets as well. Scientists have discovered them in evidence from space probes on Mars, and on Venus, and can exist on any planet or moon with a molten core.

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