Category Archives: FAQ

These are recent or frequent questions about volcanoes, volcanology, or who knows what!

How does magma form and what makes it erupt?

Magma forms from the partial melting of mantle rocks.  These little blobs of melt migrate upward and coalesce into larger volumes that continue to move upward. As they rise, gas molecules in the magma come out of solution and form … Continue reading

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Why is lava so hot?

Lava is hot for two reasons: It’s hot deep in the Earth (about 100 km down) where rocks melt to make magma. The rock around the magma is a good insulator, so the magma doesn’t lose much heat on the … Continue reading

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Why is lava different colors?

The color of lava depends on its temperature. It starts out bright orange (1000-1150 C). As it cools the color changes to bright red (800-1000 C), then do dark red (650-800 C), and to brownish red (500-650 C). Solid lava … Continue reading

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How close can I get to lava and will it hurt or kill me?

How close you can get depends on what kind of lava flow it is, and whether you are upwind or downwind. For example, the most approachable lava is pahoehoe. This is because each toe forms an insulating skin seconds after … Continue reading

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How high can lava shoot up in the air?

Fountain where lava flows enter the ocean. Kilauea Volcano. Photograph by Steve Mattox, November 24, 1992. Lava fountains can propel lava 1,000-2,000 feet (300-600 m) above the volcano. The gas dissolved inside the magma is the driving force. As the … Continue reading

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How far can lava flow?

 A lot depends on the viscosity of the lava, the terrain on which it is emplaced, and the rate at which it is being erupted to the surface. Channel feeding aa lava flow, 1984 eruption of Mauna Loa. Photograph courtesy of … Continue reading

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What are the different types of lava flows and how do they form?

There are three types of basalt lava flows: pillow, pahoehoe, and aa. Pillow Lava: Pillow lavas are volumetrically the most abundant type because they are erupted at mid-ocean ridges and because they make up the submarine portion of seamounts and large intraplate volcanoes, like the … Continue reading

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How long does it take lava to cool?

Lava cools very quickly at first and forms a thin crust that insulates the interior of the lava flow. As a result, basaltic lava flows can form crusts that are thick enough to walk on in 10-15 minutes but the … Continue reading

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How does lava change its composition?

Geochemists use several elements to track the history of a batch of magma. For our example we’ll start with magnesium (and think of it as magnesium oxide, MgO, like the geochemists do). Beneath Hawaii, when the mantle melts it produces … Continue reading

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What is lava made of?

Lava is made up of crystals, volcanic glass, and bubbles(volcanic gases). As magma gets closer to the surface and cools, it begins to crystallize minerals like olivine and form bubbles of volcanic gases. When lava erupts it is made up … Continue reading

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