Types of Volcanoes
Shield volcanoes
They are huge and made up of many layers of runny basaltic lava. Their shape is mostly broad and gently sloping.
They tend to be formed either on constructive plate margins and hotspots. They have are not very explosive and frequently erupt with lava fountaining which forms cinder and spatter cones around the main vent.
Examples of shield volcanoes are Kilauea and Maunaloa, Hawaii.
Cinder cones
This is a steep conical hill formed above a vent. They are created by strombolian eruptions. They often occur in groups and grow rapidly. Cinder cones rarely exceed 250m in height and 500m in diameter.
Parcutin, Mexico grew 300ft in 5 days, 20th Feb 1943.
Spatter cones
Created when lava contains just too much gas for a lava flow to form but not enough for shattering (explosive spray) so the lava is forced into hot clots when torn by the expanding gases in the lava; these clots are called spatter.
When the spatter falls back down and solidifies it forms steep sided accumulations around one of the vents creating a spatter cone.
Complex volcanoes
They are called so because their systems are not simple. They often have two or more vents. For example, calderas have lots of other vents that could be called volcanoes in their own right.
Composite volcanoes
They are made up of alternating layers of ash and lava. They often exceed 2500m in height, 1000sq m in surface area and 400km3 in volume. They have very explosive eruptions with viscous magma. This magma rises but often blocks the main vent which causes the gases inside to build up which increases the pressure. When the pressure gets too much, an explosive eruption occurs.
They are formed on destructive margins.
http://www.youtube.com/watch?v=lgIYDMby5WA Types of Volcanoes. One of the comments said good for A2 revision.
Different shapes:
· Concave – Agua, Guatemala
· Pyramidal – Stromboli, Sicily
· Convex-concave – Vesuvius, Naples
· Helmet shaped – Mount Rainier, Seattle
· Collapse caldera – Graciosa, Graciosa Island, Azore Islands
· Nested – El Piton in Teide, Canary Islands
· Multiple summits – Shasta, California
· Elongated along a fissure – Hekla, Iceland
Types of Volcanic eruptions
Volcanologists classify eruptions into several different types. Some are named for particular volcanoes where the type of eruption is common; others concern the resulting shape of the eruptive products or the place where the eruptions occur. Here are some of the most common types of eruptions:
Hawaiian Eruption
In a Hawaiian eruption, fluid basaltic lava is thrown into the air in jets from a vent or line of vents (a fissure) at the summit or on the side of a volcano. The jets can last for hours or even days, a phenomenon known as fire fountaining. The spatter created by bits of hot lava falling out of the fountain can melt together and form lava flows, or build hills called spatter cones.
Strombolian Eruption
Strombolian eruptions are distinct bursts of fluid lava (usually basalt) from the mouth of a magma-filled summit conduit. The explosions usually occur every few minutes at regular or irregular intervals. The explosions of lava, which can reach heights of hundreds of meters, are caused by the bursting of large bubbles of gas, which travel upward in the magma-filled conduit until they reach the open air. Strombolian eruptions are often associated with small lava lakes, which can build up in the conduits of volcanoes. They are one of the least violent of the explosive eruptions, although they can still be very dangerous if lava flows reach inhabited areas.
Vulcanian Eruption
A Vulcanian eruption is a short, violent, relatively small explosion of viscous magma. This type of eruption results from the fragmentation and explosion of a plug of lava in a volcanic conduit, or from the rupture of a lava dome (viscous lava that piles up over a vent). Vulcanian eruptions create powerful explosions in which material can travel faster than 350 meters per second (800 mph) and rise several kilometres into the air. They produce ash clouds, and pyroclastic density currents.
Plinian Eruption
The largest and most violent of all the types of volcanic eruptions are Plinian eruptions. They are caused by the fragmentation of gassy magma, and are usually associated with very viscous magmas (dacite and rhyolite). They release enormous amounts of energy and create eruption columns of gas and ash that can rise up to 50 km high at speeds of hundreds of meters per second. Ash from an eruption column can drift or be blown hundreds or thousands of miles away from the volcano. The eruption columns are usually shaped like a mushroom
Surtseyan Eruption
Surtseyan eruptions are a kind of hydromagmatic eruption, where magma or lava interacts explosively with water. In most cases, Surtseyan eruptions occur when an undersea volcano has finally grown large enough to break the water's surface; because water expands when it turns to steam, water that comes into contact with hot lava explodes and creates plumes of ash, steam and scoria.
They are huge and made up of many layers of runny basaltic lava. Their shape is mostly broad and gently sloping.
They tend to be formed either on constructive plate margins and hotspots. They have are not very explosive and frequently erupt with lava fountaining which forms cinder and spatter cones around the main vent.
Examples of shield volcanoes are Kilauea and Maunaloa, Hawaii.
Cinder cones
This is a steep conical hill formed above a vent. They are created by strombolian eruptions. They often occur in groups and grow rapidly. Cinder cones rarely exceed 250m in height and 500m in diameter.
Parcutin, Mexico grew 300ft in 5 days, 20th Feb 1943.
Spatter cones
Created when lava contains just too much gas for a lava flow to form but not enough for shattering (explosive spray) so the lava is forced into hot clots when torn by the expanding gases in the lava; these clots are called spatter.
When the spatter falls back down and solidifies it forms steep sided accumulations around one of the vents creating a spatter cone.
Complex volcanoes
They are called so because their systems are not simple. They often have two or more vents. For example, calderas have lots of other vents that could be called volcanoes in their own right.
Composite volcanoes
They are made up of alternating layers of ash and lava. They often exceed 2500m in height, 1000sq m in surface area and 400km3 in volume. They have very explosive eruptions with viscous magma. This magma rises but often blocks the main vent which causes the gases inside to build up which increases the pressure. When the pressure gets too much, an explosive eruption occurs.
They are formed on destructive margins.
http://www.youtube.com/watch?v=lgIYDMby5WA Types of Volcanoes. One of the comments said good for A2 revision.
Different shapes:
· Concave – Agua, Guatemala
· Pyramidal – Stromboli, Sicily
· Convex-concave – Vesuvius, Naples
· Helmet shaped – Mount Rainier, Seattle
· Collapse caldera – Graciosa, Graciosa Island, Azore Islands
· Nested – El Piton in Teide, Canary Islands
· Multiple summits – Shasta, California
· Elongated along a fissure – Hekla, Iceland
Types of Volcanic eruptions
Volcanologists classify eruptions into several different types. Some are named for particular volcanoes where the type of eruption is common; others concern the resulting shape of the eruptive products or the place where the eruptions occur. Here are some of the most common types of eruptions:
Hawaiian Eruption
In a Hawaiian eruption, fluid basaltic lava is thrown into the air in jets from a vent or line of vents (a fissure) at the summit or on the side of a volcano. The jets can last for hours or even days, a phenomenon known as fire fountaining. The spatter created by bits of hot lava falling out of the fountain can melt together and form lava flows, or build hills called spatter cones.
Strombolian Eruption
Strombolian eruptions are distinct bursts of fluid lava (usually basalt) from the mouth of a magma-filled summit conduit. The explosions usually occur every few minutes at regular or irregular intervals. The explosions of lava, which can reach heights of hundreds of meters, are caused by the bursting of large bubbles of gas, which travel upward in the magma-filled conduit until they reach the open air. Strombolian eruptions are often associated with small lava lakes, which can build up in the conduits of volcanoes. They are one of the least violent of the explosive eruptions, although they can still be very dangerous if lava flows reach inhabited areas.
Vulcanian Eruption
A Vulcanian eruption is a short, violent, relatively small explosion of viscous magma. This type of eruption results from the fragmentation and explosion of a plug of lava in a volcanic conduit, or from the rupture of a lava dome (viscous lava that piles up over a vent). Vulcanian eruptions create powerful explosions in which material can travel faster than 350 meters per second (800 mph) and rise several kilometres into the air. They produce ash clouds, and pyroclastic density currents.
Plinian Eruption
The largest and most violent of all the types of volcanic eruptions are Plinian eruptions. They are caused by the fragmentation of gassy magma, and are usually associated with very viscous magmas (dacite and rhyolite). They release enormous amounts of energy and create eruption columns of gas and ash that can rise up to 50 km high at speeds of hundreds of meters per second. Ash from an eruption column can drift or be blown hundreds or thousands of miles away from the volcano. The eruption columns are usually shaped like a mushroom
Surtseyan Eruption
Surtseyan eruptions are a kind of hydromagmatic eruption, where magma or lava interacts explosively with water. In most cases, Surtseyan eruptions occur when an undersea volcano has finally grown large enough to break the water's surface; because water expands when it turns to steam, water that comes into contact with hot lava explodes and creates plumes of ash, steam and scoria.