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What causes a volcano erupt?

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A volcano begins as melted rock (magma) which rises from deep inside the earth toward the surface. As the gas-filled magma rises ...

Why are there volcanoes? Why do they erupt? | Volcano World ...

volcano.oregonstate.edu/why-are-there-volcanoes

Volcanoes erupt because of density and pressure. The lower density of the magma relative to the surrounding rocks causes it to rise (like air bubbles in syrup).

USGS FAQs - Volcanoes General - How Do Volcanoes Erupt?

www2.usgs.gov/faq/categories/9819/2729

Some volcanic eruptions are explosive and other are not. How explosive an eruption is depends on how runny or sticky the magma is. If magma is thin and ...

How It Happens | Volcanic Eruptions - Video - NYTimes.com

www.nytimes.com/video/science/100000003431211/how-it-happens-volcanic-eruptions.html

Jan 5, 2015 ... The eruption of a volcano can be one of the planet's most destructive events — spewing huge amounts of rock, gas and ash that can kill people.

www.ask.com/youtube?q=What Makes A Volcano Erupt&v=-kQwudeT3ww
Jun 29, 2013 ... A quick and fun cartoon lesson about volcanoes. Great for teachers and students- hope you guys enjoy! Be sure to subscribe if you like it, there ...

Why do volcanoes erupt? What creates eruptions? - eSchooltoday

eschooltoday.com/volcanoes/how-do-volcanoes-erupt.html

Find out what the earth make-up is, and how extreme pressure build up inside the earth forces molten matter to be expelled out to the surface, causing a volcanic ...

What Causes A Volcanic Eruption? | IFLScience

www.iflscience.com/environment/are-explosive-volcanic-eruptions-triggered-frictional-heating/

Jan 6, 2016 ... A team of volcanologists led by the University of Liverpool have released a perhaps controversial Nature study on the causes of volcanic ...

Volcanoes and volcanic eruptions - BBC

www.bbc.co.uk/schools/gcsebitesize/geography/natural_hazards/volcanoes_rev1.shtml

A secondary school revision resource for GCSE Geography covering key facts about volcanoes and volcanic eruptions.

Volcanoes - Weather Wiz Kids weather information for kids

www.weatherwizkids.com/weather-volcano.htm

An erupting volcano can trigger tsunamis, flash floods, earthquakes, mudflows and ... Lava domes are formed when erupting lava is too thick to flow and makes a ...

What Makes A Volcano Erupt? - Catalogs.com

www.catalogs.com/info/earth-science/what-makes-a-volcano-erupt.html

There are few geological events that are as dramatic as a volcanic eruption except maybe a hurricane, tornado or a tsunami. Each is drama.

Answer
Several factors trigger volcanic eruptions, including the buoyancy of magma, a build-up of pressure from the gases in the magma and an injection of new magma into a full magma chamber.
When a part of the earth's upper mantle or lower crust melts, magma forms. A volcano is essentially an opening or a vent through which this magma and the dissolved gases it contains are discharged.
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What makes a volcano erupt? | Reference.com

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Volcanoes erupt due to pressure that the weight of the rocks puts on the magma and forces it to the surface out any available vent or exit provided to it.

What causes a volcano to erupt and how do scientists predict ...

www.scientificamerican.com

When a part of the earth's upper mantle or lower crust melts, magma forms. A volcano is essentially an opening or a vent through which this magma and the ...

How Do Volcanoes Erupt? - Universe Today

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May 26, 2016 ... Volcanic eruptions are driven by a combination of mechanisms, ... What is it exactly that makes molten rock rise from the Earth's interior and ...