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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. A shield volcano is named so due to their similarity to a warrior’s shield lying on the ground. Mauna Loa is the largest shield volcano found on the Island of Hawaii. Other famous examples of shield volcanoes include Wolf volcano in the Galapagos Islands and Nyamuragira in the Democratic Republic of Congo.
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What is a Shield Volcano? A shield volcano is a broad volcano with sloping sides that is formed mainly out of runny lava that flows out of its central summit vent. Examples of Shield Volcano: Mauna Loa in the Island of Hawaii, Wolf volcano in Galapagos Islands and Nyamuragira in the Democratic Republic of Congo |
How Are Shield Volcanoes Formed?
Volcanoes are patches on Earth that erupt magma from underneath the Earth’s chambers. The magma upon reaching the surface transforms into ash, lava and volcanic gases. Over time, with many such eruptions, a volcano is formed layer by layer until the magma in the chamber beneath is emptied.
The basaltic lava that flows out of a shield volcano gives a shield volcano a different shape as compared to other volcanoes. The basaltic lava of a shield volcano is of low viscosity that can quickly flow and cover large areas. The lava from each shield volcano eruption eventually hardens, and the next eruption flows over and hardens on top of the previous one. Over time, the multiple eruptions of shield volcanoes build up, one on top of the other, giving rise to a shield volcano. This process creates a gradual increase in elevation over time, building up the shield volcano’s size.
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Formation of Shield Volcano A shield volcano is built mainly out of basaltic lava of low viscosity. The lava flows out, cools and hardens, adding to layers of cooled and hardened lava underneath it. This process creates a gradual increase in elevation over time resulting in the formation of shield volcanoes. |
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Shield Volcano Characteristics
The characteristics of a shield volcano are as follows:
- Shield Volcanoes are composed of basaltic magma (high in temperature, very low on silica and gas content.)
- The lava erupted from the shield volcanoes are runny and non-acidic.
- As the erupted lava is runny, they flow long distances before they solidify, this results in the gentle sides of shield volcanoes.
- There are shorter periods between eruptions, and the explosions are less violent.
- Shield volcanoes are found on divergent plate boundaries.
Difference between Shield Volcanoes and Composite Volcanoes
Shield Volcano and composite volcano are two main types of volcanoes with different characteristics and are formed at different places. There are many differences between the shield and composite volcanoes which we have discussed below for your reference.
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Shield Volcano |
Composite Volcano |
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They are composed of basaltic magma that has a high temperature and low content of silica and dissolved gases. This type of magma results in less explosive activity on reaching the surface. |
They are composed of andesitic magma that is low in temperature but high content of silica and dissolved gases. This type of magma is likely to explode on reaching the surface. |
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The basaltic lava of a shield volcano is runny and is of low viscosity |
The lava of a composite volcano is acidic and is of high viscosity |
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The lava flows very long distances before it solidifies resulting in the gentle sides of a shield volcano |
The lava flows a short distance before it solidifies resulting in the steep sides of a composite volcano |
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Less violent eruptions |
Violent eruptions |
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Shorter period between eruptions |
A longer period between eruptions |
Read more: Types of Volcano
Frequently Asked Questions on Shield volcanoes
What are shield volcanoes? Give examples.
Shield volcanoes are broad volcanoes with sloping sides that are mainly made of basaltic lava. The Mauna Loa on the Island of Hawaii and the Wolf volcano in Galapagos Islands are examples of shield volcanoes.
How are the shield volcanoes formed?
Shield volcanoes are mainly composed of lava that flows out of it. Multiple eruptions of lava from a shield volcano build up, one on top of the other, to giving rise to a shield volcano.
Where are the shield volcanoes formed?
Shield volcanoes are found on divergent plate boundaries, where two plates move away from one another.
Which is the biggest shield volcano?
Mauna Loa on the Island of Hawaii is the biggest shield volcano.
What is the main difference between a shield volcano and a composite volcano?
The main difference between the two is that a shield volcano is composed of basaltic lava while a composite volcano is composed of andesitic magma.
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