Published on March 1, 2014
Learning Goals: Be able to identify different types of volcanoes. Understand and explain how different types of volcanoes form, and the hazards linked with them. Consider why people might live near volcanoes
Why are some volcanoes more violent than others? There are different types of volcanoes that form as a result of different processes…
Hotspot Volcano Some volcanoes do not cluster at plate boundaries... Why? •When a tectonic plate moves over a very hot part of the mantle, a plume of magma rises. This is known as a HOT SPOT. •Hot spots are responsible for the chain of islands we know as Hawaii.
Eruptions are not usually explosive because the magma tends to be more fluid, so less pressure builds up. Lava is the main hazard linked to hotspot The shape of the volcano is usually low and wide and is called a SHIELD VOLCANO
Hawaii E.g. Kilauea in Hawaii This is the most active volcano in the world.
Shield volcanoes also form at divergent plate boundaries: When the plates move away from each other, molten magma rises up from deep inside the mantle, and melts the upper mantle.
Like hotspot volcanoes, the magma rising up from the mantle is very hot, and therefore very fluid. Main hazards linked with volcanoes at divergent boundaries are: Lava Ash The magma runs down the sides of the volcano creating a low, wide shape Shield Volcano
An example of a volcano at a divergent plate boundary is: Grimsvötn, Iceland
Oceanic crust and continental crust are forced together Oceanic crust is dense and heavy, and is forced underneath the continental crust This is known as SUBDUCTION
As the oceanic crust is subducted, it heats up making a very VISCOUS or very sticky magma Volcanoes become steep sided and eruptions are very explosive
Explosive eruptions result in rocks, lava and ash exploding from the volcano. This mixes with gas and steam and causes PYROCLASTIC FLOWS. Lahars are also common. A lahar is a type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris, and water.
Layers of lava and ash gather around the vent and this creates a COMPOSITE VOLCANO White Island – New Zealand (north of the North Island)
An example of a composite volcano at a convergent plate boundary is: Mount St Helens, Washington, USA
Principal Types of Volcanoes. Geologists generally group volcanoes into four main kinds--cinder cones, composite volcanoes, shield volcanoes, and lava domes.
A volcano is an opening in Earth's crust where magma breaks through, raining down molten rock, ash and gases. There are several types of volcanoes.
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The U.S. Geological Survey estimates that there are about 65 active volcanoes in the United States and its territories. The Dynamic maps viewer (shown at ...
Geologists generally group volcanoes into four main kinds—cinder cones, composite volcanoes, shield volcanoes, and lava domes. Cinder cones
Different types of volcano. Volcanoes can be described in terms of activity and can be: still active and erupt frequently; dormant (temporarily inactive ...
Many people are interested in ways to classify volcanoes. There is probably a natural human instinct to try and give labels to all things. This is not a ...
What are the three main volcanoes? There are three main types of volcano - composite or strato, shield and dome. Composite Volcanoes. Composite volcanoes ...