Unlike composite volcanoes, shield volcanoes occur where the tectonic plates move away from one another (constructive tectonic boundaries). Inside these types of volcanoes, the lava is thin and runny.
It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more viscous lava erupted from a stratovolcano. Repeated eruptions result in the steady accumulation of broad sheets of lava, building up the shield volcano's distinctive form.
Shield volcanoes are found on constructive plate margins close constructive plate marginAn area where two tectonic plates are moving away from one another., where two plates move away from one another. Shield volcanoes have the following characteristics: basic lava, which is non-acidic and very runny.
How is a shield volcano formed at a constructive plate boundary?
However, unlike at destructive plate boundaries where eruptions can be short and violent, at constructive plate boundaries eruptions are typically prolonged and less explosive. These slow eruptions of thin basaltic lava lead to the formation of volcanoes with wide and gently sloping sides known as shield volcanoes.
Shield volcanoes are usually constructed almost entirely of basaltic and/or andesitic lava flows which were very fluid when erupted. They are built by repeated eruptions that occurred intermittently over vast periods of time (up to a million years or longer). Shield volcanoes are much wider than they are tall.
Basalt plateau refers to an extensive, thick, smooth flow or succession of flows of high-temperature, fluid basalt erupted from fissures, flooding topographic lows, and accumulated to form a plateau. It is the least explosive type of volcano.
What is the difference between a stratovolcano and a shield volcano?
Stratovolcanoes have relatively steep sides and are more cone-shaped than shield volcanoes. They are formed from viscous, sticky lava that does not flow easily. The lava therefore builds up around the vent forming a volcano with steep sides.
Stratovolcanoes, or composite volcanoes, are most likely to explode due to the higher gas content and viscosity of the magma they erupt. This includes famous examples like Mount St. Helens. This type of volcano is found in areas of subduction and continental plate collisions.
These results show that Pūhāhonu is the largest shield volcano on Earth. It is twice the size of Mauna Loa volcano (148 ± 29 vs. ), which was assumed to be not only the largest Hawaiian volcano but also the largest known shield volcano on Earth. 2.
Because they are made up viscous lava, domes are usually steep-sided. They typically have rough brecciated surfaces, and sometimes they have glassy rinds due to quenching of the hot lava once it was erupted onto the surface. Most domes are relatively small volcanoes with limited volume.
Basic lava contains less silica, this allows the gasses to escape and gives a runny lava. Eruptions of this type of lava a gentler and this along with it being runny allows the lava to flow further. Volcanoes of this type of lava will have gently sloping sides.
A shield volcano is a broad volcano with shallow inclining sides. Shield volcanoes are formed from many magma flows of low viscosity. The magma flows out of the vent and slides down the slopes of the volcano and builds up the size.
Shield volcanoes have the following characteristics: Basaltic magma, which is high in temperature, very low on silica and with low gas content. This type of magma produces fluid lava with very little explosive activity. Basic lava, which is non-acidic and very runny.
Mafic lava flows can travel quite far before solidifying completely, and the type of volcano that forms from mafic lava is called a shield volcano (Figure 9.9).
The most violent eruption registered in history was that in the La Garita Caldera in the United States. It occurred 2.1 million years ago and formed a 35 x 75 km crater, drastically changing the climate on Earth. Fortunately, these eruptions are rare: they occur every 50,000 or 100,000 years.
It's still active…and it will erupt again. Mount Vesuvius is listed among the most dangerous volcanoes in the world. Volcanologists and geologists alike agree that the next volcanic eruption is overdue and that when it does happen, it will be big.
So Yellowstone is not a stratovolcano. It's not a shield volcano. It's not a cinder cone or a lava dome or a coulee or a plug. Rather, it demonstrates a style of volcanism that includes rare large explosive eruptions associated with caldera collapse, preceded and followed by smaller eruptions.
Examples of shield volcanoes are Kilauea and Mauna Loa (and their Hawaiian friends), Fernandina (and its Galápagos friends), Karthala, Erta Ale, Tolbachik, Masaya, and many others. Here are 4 of the volcanoes that comprise the big island of Hawai'i.
Mauna Loa is considered to be a shield volcano, meaning it was created by the flow of lava over time. Such volcanoes are not particularly tall (at least in the world of volcanoes). Instead, they grow wide like shields (hence the name).
The type of volcano that is the most explosive is called a "supervolcano." Supervolcanoes are, roughly speaking, volcanoes that are capable of erupting with the highest level of explosivity on the Volcanic Explosivity Index (VEI).
The six eruption types are in order from least explosive to the most explosive; Icelandic, Hawaiian, Strombolian, Vulcanian, Pelean, and Plinian. Notice how, as the eruptions become more violent, the cone shapes become more steeply constructed.
Cinders are small chunks of scoria. Photograph by Katie KellerLynn (Colorado State University). Cinder cones are more technically known as scoria cones. Scoria are irregularly-shaped, highly vesicular (bubble-shaped cavities) fragments of lava that are erupted into the air and are typically solid when they land.
