What Causes Volcanoes To Form At A Divergent Plate Boundary?

Describe how plate tectonics is related to the formation of volcanoes?

Which type of plate margin commonly forms volcanoes? Name one of the most popular volcanoes in the United States or the world

Dense oceanic plates will be pushed down or pulled down and under less dense continental plates. When this happens the water filled ocean floor, that is now under the continent, will melt at a lower temperature than the rock around it. This melted rock, magma, pushes upward lifting up mountains and volcanoes.

This occurs on an active margin. On a convergent oceanic to continental plate boundary. Divergent plate boundaries can also form volcanoes but they are underwater.

Most popular volcano in the US would be Mt. Saint Helens in the Cascades. Which is build up from the North American plate overriding the Juan de Fuca plate.

why does it make a difference whether a volcano sits on the edge of the plate or on it?

^ title also another question-WHY does it take longer to travel from mt st helens to olympia than to portland?

Volcanoes such as the Cascade range do not form directly on "subduction" plate boundaries but near the margins. They form about 80-130 kilometers inland over the Wadati-Benioff zone. http://en.wikipedia.org/wiki/Wadati-Benioff_zone
Or they form off shore in Volcanic Arcs but never on the boundary itself.

The volcanoes of Iceland are located on the mid-oceanic ridge where the ridge is above sea level. A mid-oceanic ridge or a rift valley are the only settings I know of where a volcano forms exactly on the boundary. Both these are "divergent" plate boundaries.

The differences will be in the type of eruption, the source stock/composition of the magma and lava and the height of the volcano--which to list would exceed the space provided by !Y Answers. if you Wiki "Volcano" there are links that will cover all the relative answers as to the characteristics of volcanoes formed on at subduction convergent boundaries and divergent boundaries .

As to the second question, I don't know that it does. If so I assume it has to do with relative locations, terrain, and road networks.

Where do volcanoes occur on the earths surface?

Volcanoes can occur along convergent or divergent plate boundaries. Along the divergent boundaries the volcanoes are the result of melting of the rock below the surface due to a decrease in pressure. Along convergent plate boundaries, the hot rock below the surface melts if volatiles (from the subducting plate) mix with the rock. This lowers the rocks melting point to produce magma that can lead to volcanic eruptions. Another way volcanoes can occur is from mantle plumes heating crustal rocks. The added heat simply melts the rocks. An example of this type of volcanic occurence is the Hawaiian Islands. They are far from any plate boundary and are called "hot spot" volcanics. There are many on the planet.

Why do volcanoes usually form on the edges of tectonic plates?

I know that not all volcanoes form on the edges of tectonic plates but i need to know why they usually do. Please include sources. Thank you!

They form where magma rises to the surface, this would be at both divergent boundaries and at a type of convergent boundary called a subduction zone, where one plate slides beneath another and sinks into the earth's mantle

2 ways volcanoes form?

what are two ways volcanoes form please dont copy n paste somethin from another website type it in your own words(;

Volcanoes form:

(1) At convergent boundaries (subduction zones), where one plate is being subducted (going beneath) the other. At the right depth, it will begin to melt, and form new magma. This magma will rise, and can punch out of the overriding crust to form a new volcano. On land, this creates a volcanic mountain chain (Juan de Fuca plate subducts beneath North American plate, creates Cascade Mountains). In the ocean, this will create a volcanic island arc (Pacific plate subducts beneath North American plate, creates Aleutian Island Arc). In general, these volcanoes are more felsic ("granitic") in nature, and more explosive. These are usually stratovolcanoes/composite volcanoes.

(2) At hot spots, where a large magma plume has risen from the mantle (generally, but not always beneath oceanic crust) in the middle of a plate (away from a boundary) and cut through the crust to form a volcano. Given time and enough erupting, it will rise through the ocean surface and emerge as a volcanic island - which is how the Hawaiian Islands and Hawaiian-Emperor Seamount range formed. These are generally shield volcanoes.

(3) There is actually a third method. At divergent boundaries, where crust is moving apart, magma is wedging its way between the crust, and often erupts as a volcano. We just generally don't think of these because they're usually thousands of feet below the ocean, where most people don't care about. However, if you visit Iceland, you can walk up and see divergent boundary of the Mid-Atlantic Ridge splitting the small country in two. When it gets angry, it throws beautiful, mile-long fissures of lava hundreds of feet into the air. That's definitely a volcano - a fissure volcano.

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