How magma behaves when it gets gassed up Geologist Ben Andrews taking video on the volcano Santa MarĂ­a in Guatemala. (Smithsonian photo/gnuckx, public domain)
How magma behaves when it gets gassed up
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Lava is the most famous hazard of volcanoes. It is featured in movies. It used to describe lamps, chocolate cakes and mobile phone cases. But lava is only part of the volcano story. Lava is what we call magma when it flows out of a volcano. Magma is molten - or melted - rock. You would not want to stand in lava. It can be as hot as 2,000 Fahrenheit. At a walking pace you could outrun the majority of lava flows. So, what’s so hazardous about a volcanic eruption?

Sometimes magma does not flow out of a volcano. Instead, it explodes. When that exploding mixture of hot gas, magma, and rock comes out, it is fast and unpredictable. 

In an explosive eruption, pieces of hardening magma and rock are spewed upward. They form a hot plume of gas. They range from the tiny particles that make up volcanic ash to chunks the size of cars. As the plume blows downwind, it drops materials like a hail storm. It litters the landscape with volcanic rocks. A pyroclastic flow of hot gases carrying the heavier material may pick up speed as it sweeps down from the volcano. As the flow mixes with the surrounding air, lighter ash may get lofted up in a cloud. It can travel as far as thousands of miles. 

The bigger chunks are an immediate hazard to people and wildlife around the volcano. But the cloud of ash takes a long-term toll that can be devastating. The 1980 eruption of Mount St. Helens in Washington state produced a pyroclastic flow that scoured the landscape at speeds up to 600 miles per hour. It lofted ash that settled on 11 states over the next few days. 

The 2010 eruption of Iceland’s Eyjafjallajökull volcano sparked electrical storms. It had an ash plume more than 5 miles high, spreading over Europe and grounding airline travel for days. 

Geologists who study volcanoes - volcanologists - are trying to better understand the behavior of these pyroclastic currents. Given the danger of capturing data directly from an explosive eruption, volcanologists such as Smithsonian’s Dr. Ben Andrews have found ways to capture data from a distance and simulate flows in laboratories. Ben’s Eruption Simulator uses laser beams and talcum powder to observe how erupted materials get distributed upward and outward in different scenarios.  

Learn more about Ben’s volcano research in the "Smithsonian Science How" webcast on Thursday, Dec. 14, 2017. Watch How Volcanic Eruptions Send Materials Up and Out, airing at 11 a.m. and 2 p.m. EST on the Q?rius website. Ben will take you on an explosive journey while answering your questions live. You can also get teaching resources to use with the webcast.

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CRITICAL THINKING QUESTION
What is magma?
Write your answers in the comments section below


COMMENTS (127)
  • ChloeT-del
    11/28/2017 - 05:27 p.m.

    This article is about lava and magma. Lava and magma are two different things. Lava is a hot,burning liquid erupted from a volcano. Magma is a hot liquid in the earth's crust. When magma reacts to gas, it turns into chunks.

  • MarianaG-del
    11/28/2017 - 05:30 p.m.

    This article was about magma. It was also about its effect on the surrounding area.

  • SophiaD-del1
    11/28/2017 - 05:31 p.m.

    The main idea is that there is more to the volcanic explosions that we see than just lave. The lava spewing from the mouth of a volcano, people can walk away from. The real danger, besides lava, are the gasses, boulders, and ash that escape with it! They rain on the Earth like hail and blacken out the sky. The gas can even drag ash for thousand of miles.

  • DevanS-del
    11/28/2017 - 05:34 p.m.

    I found this article very interesting. I thought it informative in many ways. I learned that volcanos spew out a mixture of ash and magma. Magma is molten - or melted - rock. It melts quickly but can travel far distances once in the air. This depends on it's size.

  • SamanthaM-del1
    11/28/2017 - 05:36 p.m.

    Magna is molten- or melted rock. In this article, we learn more about magma and how it interacts with volcanoes. I learned that sometimes it flows out of a volcano, or in some cases- can actually explode.

  • ElvinaI-del
    11/28/2017 - 06:10 p.m.

    Volcanoes can be very dangerous. They leave harmful effects on the Earth and its atmosphere. When volcanoes erupt the magma and lava can travel for miles but will soon harden up.

  • DavidN-del
    11/28/2017 - 06:17 p.m.

    Molten rock within the earth from which igneous rock results by cooling

  • GregoryM-del
    11/28/2017 - 06:28 p.m.

    The most dangerous and well known part of a volcano is lava also known as magma. Magma is molten or melted rock. You can avoid it at a walking pace.

  • JustinM-del
    11/28/2017 - 06:56 p.m.

    this article is about how magma behaves when it gets gassed up and the explosive eruptions from volcanos

  • JasminderK-del
    11/28/2017 - 07:41 p.m.

    This article is explaining why and how volcanic eruptions are so dangerous , volcanos spew lava and ashes upwards with tiny pieces of ash or giant pieces of rock al at the same time spew out and rapidly fall downward causing danger to people.

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