Volcanic Eruption: Gases Released & Their Effects

Lesson Transcript
Instructor: Rebecca Gillaspy

Dr. Gillaspy has taught health science at University of Phoenix and Ashford University and has a degree from Palmer College of Chiropractic.

Volcanic eruptions can cause a lot more damage than just lava. Learn about the gases associated with volcanic eruptions as well as the effects they have on the atmosphere such as water vapor, carbon dioxide, sulfur dioxide, and more. Updated: 09/27/2021

Volcanic Eruptions

This lesson is about volcanic gases, but you might want to look at it as your Volcano Survival Guide. There's no doubt that volcanoes can be destructive and dangerous. However, when you think of the dangers associated with a volcano, you likely get an image in your mind of the flowing, red-hot lava oozing down the side of a volcano.

What you might not consider are the toxic gases that explode into the atmosphere and get dispersed over wide areas by the wind. These gases have as much, if not more, of a potential to be detrimental to your health than a lava flow. So, here's my short list of volcano survival tips: First, if there is a river of red-hot lava coming your way, RUN! Second, if you are near an erupting volcano, hold your breath!

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  • 0:06 Volcanic Eruptions
  • 0:56 Volcanic Gases
  • 2:14 Water Vapor
  • 3:17 Carbon Dioxide
  • 4:04 Sulfer Dioxide
  • 6:37 Lesson Summary
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Volcanic Gases

Okay, so maybe these tips are a bit vague. Let's take a closer look at the gases produced during a volcanic eruption so we can fully understand their effects. The gases that are released during a volcanic eruption come from deep within the Earth. They are dissolved in magma, which are hot molten rock found in the deeper layers of Earth. Because this melted rock is less dense than the rocks surrounding it, it rises up toward the Earth's surface. As it does, the dissolved gases within the magma begin to form bubbles, which increase the volume of the mixture and make the magma even less dense. As the magma continues its journey toward the Earth's surface, the volume and pressure continue to build and can lead to a volcanic eruption, which sends volcanic gases miles high into the Earth's atmosphere.

Once free of the volcano, some of these gases get carried by the wind and can travel for thousands of miles, if conditions are right, while other gases get trapped in the higher layers of the atmosphere. The main volcanic gases are water vapor, carbon dioxide, and sulfur dioxide, and there are other gases released in lesser amounts. Let's look at each of these main gases and their effects.

Water Vapor

The most abundant gas expelled during a volcanic eruption is water vapor. Water vapor is not toxic and because so much is expelled during an eruption, it can actually benefit the planet by pulling water from deep within the Earth and adding it to the water cycle. However, there can be a downside to water vapor emissions. According to researchers from the Department of Meteorology at the University of Reading in Britain, water vapor emitted during a volcanic eruption can impact climate change.

Large volcanic eruptions can launch water vapor up into the stratosphere, which is a layer of the Earth's atmosphere about six to 30 miles above the Earth's surface. This is the layer that you are in when you are in a jet plane that wants to fly up high to avoid storms. The research found that increased amounts of water vapor in the stratosphere can force surface temperatures to rise, adding to the warming of the Earth's surface, much like we see when carbon dioxide is added to the atmosphere by human activities, such as burning fossil fuels.

Carbon Dioxide

Speaking of carbon dioxide, this is another gas that is commonly expelled during the volcanic eruptions. Carbon dioxide is considered a greenhouse gas, which means that it is an atmospheric gas that contributes to warming of the Earth's surface. However, the amount of carbon dioxide emitted from volcanoes each year is not thought to contribute to global climate changes as much as man-made emissions of the gas. Carbon dioxide emissions from a volcano tend to become diluted quickly, and therefore do not typically pose a direct threat to people. However, carbon dioxide is heavier than air, so it can accumulate in low-lying areas. If a person were to enter a low area where the gas settled after a volcanic eruption, then breathing this concentrated air could prove fatal.

Sulfur Dioxide

Another common gas emitted during a volcanic eruption is sulfur dioxide, and emissions of this gas may have the most significant impact on the Earth's climate. When sulfur dioxide is ejected into the stratosphere it gets converted to sulfuric acid aerosols, which are tiny sulfuric acid droplets. These aerosols hang in the stratosphere and travel the Earth for long periods of time, even years after an eruption. While in the stratosphere, they reflect the sun's rays back into space, preventing them from reaching earth. Therefore, sulfur dioxide emissions can actually help cool the Earth's surface.

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