Volcanoes

Volcano Diagram

How do volcanoes work?

• Volcanoes are formed when magma from within the Earth's upper mantle works its way to the surface.
• At the surface, it erupts to form lava flows and ash deposits.
• Over time as the volcano continues to erupt, it will get bigger and bigger.
• www.weatherwizkids.com/weather-volcano.htm

Magma Chamber

• A magma chamber is a large underground pool of molten rock sitting underneath the Earth’s crust. This magma is less dense than the surrounding mantle and so it seeps up to the surface through cracks and flaws in the crust. When it reaches the surface, it results in a volcanic eruption.
• http://www.universetoday.com/29125/parts-of-a-volcano/

Main Vent

• A volcano’s main vent is the point in the Earth’s crust where hot magma has reached the surface. The familiar cone-shaped volcano builds up as ash, rock and lava ejected during eruptions fall back to Earth around the vent.
• http://www.universetoday.com/29125/parts-of-a-volcano/

Crater

• A volcanic crater is a circular depression in the ground caused by volcanic activity. A volcano’s vents are located at the bottom of the crater.
• http://www.universetoday.com/29125/parts-of-a-volcano/

Pipe

• A vertical conduit below a volcano through which magma has passed and that has become filled with solidified magma, volcanic breccia, and fragments of older rock.
• http://dictionary.reference.com

Hot Spots

• The places known as hotspots or hot spots in geology are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the mantle elsewhere. They may be unanimously hot, and provide a great deal of molten magma. They may be on, near to, or far from tectonic plate boundaries.
• en.wikipedia.org/wiki/Hotspot_(geology)

Composite Volcano

• They are typically steep-sided, symmetrical cones of large dimension built of alternating layers of lava flows, volcanic ash, cinders, and blocks
• When a composite volcano becomes dormant, erosion begins to destroy the cone.
• http://www.factmonster.com/ipka/A0862596.html

Picture of Composite Volcano

Shield Volcanoes

• Shield volcanoes, are built almost entirely of fluid lava flows. Flow after flow pours out in all directions from a central summit vent, or group of vents, building a broad, gently sloping cone of flat, domical shape, with a profile much like that of a warrior's shield.
• http://www.factmonster.com/ipka/A0862596.html

Picture of Shield Volcano

Cinder Cone Volcanoes

• Cinder cones are the simplest type of volcano. They are built from particles and blobs of congealed lava ejected from a single vent. As the gas-charged lava is blown violently into the air, it breaks into small fragments that solidify and fall as cinders around the vent to form a circular or oval cone.
• http://www.factmonster.com/ipka/A0862596.html

Picture of Cinder Cone Volcano

What causes a volcano to erupt?

• Magma rises through cracks or weaknesses in the Earth's crust. When this pressure is released, as a result of plate movement, magma explodes to the surface causing a volcanic eruption.
• http://www.bbc.co.uk

How do volcanoes affect mountain formation?

• Movements of tectonic plates create volcanoes along the plate boundaries, which erupt and form mountains. A volcanic arc system is a series of volcanoes that form near a subduction zone where the crust of a sinking oceanic plate melts.
• http://en.wikipedia.org/wiki/Mountain_formation#cite_note-Butz-7

Subduction

• In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate and sinks into the mantle as the plates converge.
• en.wikipedia.org/wiki/Subduction

Where do volcanoes form?

• At Subduction Boundaries- When an oceanic plate is forced beneath another plate, volcanoes always form on the overriding (top) plate. If the top plate is a continental plate, a range of mountains and volcanoes forms.

Where do volcanoes form?

• At Divergent Boundaries- Most of the magma that reaches Earth’s surface does so here, along the mid-ocean ridges. -Thus, most of Earth’s volcanic activity takes place beneath the oceans!

Where do volcano boundaries form?

• Over Hot Spots- areas of volcanic activity that form from plumes of hot, solid material that have risen from deep within Earth’s mantle -A hot spot stays in the same place in the mantle, as the lithospheric plate slides over it.

Citation for where volcanoes form

• http://schoolworkhelper.net/how-and-where-volcanoes-form/

How do scientists learn about volcanoes?

• They measure ground movement, they take the Earth's temperature, they check the geophysical properties, and they study the volcano's past, and they measure seismic activity.