Shield Volcano: Formation, Components, and Types of Volcanoes

Answer: A shield volcano is a volcano with sloping sides that are formed due to the continuous flow of the runny lava that flows out of its central summit vent. Because the lava is runny and has low viscosity the lava can travel from the actual eruption side and creates a shield-like structure.

Examples of the Shield lava include Mauna Lao in Hawaii which is the largest shield volcano, Wolf volcano in Galapagos, and Piton de la Fournaise in the Reunion islands.

Answer: The types of volcanoes are classified on the basis of their shapes and sizes. Following are the three main types of volcanoes: -

1. Cinder cone: As the name suggests, the cinder cones are made up of ejected igneous rocks which are called “cinders”. Cinder cone volcanoes are small in the area and usually have a circular footprint. Their flanks usually slope at an angle of about 30 to 40 degrees. Cinder cone volcanoes are the simplest and largely found type of volcano. It is also known as pyroclastic cones.

2. Shield Volcano: They are large in volume, area, and diameter. Shield volcanoes are entirely made up of fluid lava flows. Continuous flowing lava forms layer after layer on the surface in all directions from a central summit vent and forms a shield-like structure. It builds a broad, gently sloping cone of flat, domical shape. Some of the largest volcanoes in the world are shield volcanoes because they are large in area.

3. Composite Volcano: Composite volcanoes are built from many layers of hardened lava. Composite volcanoes are violent and destructive in nature. They can sometimes erupt so violently that they collapse in on themselves. Some layers of the composite volcano might be formed from lava, while others might be ash, rock, and pyroclastic flows. Composite volcanoes usually build a large quantity of thick magma which blocks up inside the volcano. This causes the volcanic explosion.

Answer: Shield Volcano:

1. They are made up of basaltic lava. This basaltic lava is high in temperature, very low on silica and gas content. Therefore, it is not very explosive in nature.
2. The basaltic lava runs continuously and have low viscosity.
3. The lava travel very long from the actual eruption side and solidify quickly. This results in the gentle sides of the shield volcano.
4. The shield volcano is less violent in nature.
5. The period between the eruptions are shorter.

Composite Volcanoes

1. The Composite volcanoes are made of andesitic magma which is low in temperature but has a high content of silica and gases. Therefore, it is very explosive in nature.
2. The lava is acidic in nature and has high viscosity.
3. The lava does not flow through the long distance. When it solidifies, it results in the steep sides of the composite volcano.
4. Composite volcanoes are violent in nature.
5. The period between the eruptions is longer.

Answer: The most important part in the composition of the shield volcano is lava. The shield volcanoes have basaltic lava which is high in temperature and low in silica and dissolved gases. This allows the lava to flow from the distance of the actual eruption site. The lava hardens quickly. In a shield volcano, the lava is continuously flowing which makes the different layers every time the lava erupts. This results in the formation of the shield-like structure.

Answer: The main component of the Shield volcano is its shield itself. The shield feels like a Warrior’s shield lying on the earth’s surface. There are also some other important parts of the shield volcano. The caldera is the topmost part of the volcano. The lava erupts from the caldera, but it is not the only place from where the lava emerges. The vents are present on the sides of the shields. They are the openings through which the lava can erupt. Below the crust, under the caldera the magma chamber is present. When the magma emerges from the crust while the eruption is happening, the name magma changes to lava.

Answer: The characteristics of the shield volcano are as follows:

1. The lava that is erupted from the shield volcanoes is the basaltic lava. The basaltic lava is high in temperature, low on silica and gas content.
2. Before the lava hardens it flows through the long distances, because of the runny nature of the lava erupted. This results in the formation of the gentle sides of the shield volcanoes.
3. The lava burst out from the shield volcanoes is runny and non-acidic in nature.
4. The period between the two eruptions is shorter compared to the other volcanoes.
5. The explosions in the shield volcanoes are less violent. They are quiet and immense.
6. They are found on the divergent plate boundaries.

Answer: There are three different types of volcanoes based on their size and shapes. A composite volcano is one of them. A composite volcano is also known as Stratovolcano. It is built from many layers of hardened lava. Composite volcanoes are violent in nature. They can sometimes erupt so violently that they collapse in on themselves. Some layers of the composite volcano might be formed from lava, while others might be ash, rock, and pyroclastic flows. Composite volcanoes usually build a large quantity of thick magma which blocks up inside the volcano. This causes the volcanic explosion. Mount St. Helens, Mount Rainer, Mount Hood, and Mount Fuji in Japan are some of the examples of Composite Volcanoes.

Answer: Basaltic lava flows continuously from the volcano which is the main component in the formation of shields. This basaltic lava is high in temperature, low on silica and dissolved gases. The basaltic lava quickly gets hardened and forms a layer on the outer surface of the volcano. Whenever the eruption happens, the new layer is created and as the basaltic lava is running continuously there are many layers formed that form a shield-like structure. The basaltic lava has a low viscosity which allows it to travel through the distance from the actual site of eruption.