The Loudest Sound in the World

SCIENCE

On 27 August 1883, the Earth let out a noise louder than any it has made since. It was heard 3,000 miles away “like the distant roar of heavy guns.” Think, for a moment, just how crazy this is. If you’re in Boston and someone tells you that they heard a sound coming from New York City, you’re probably going to give them a funny look. But Boston is a mere 200 miles from New York. What we’re talking about here is like being in Boston and clearly hearing a noise coming from Dublin, Ireland. (Nautilus)

What caused such a roar? Use our resources to find out.

This beautiful illustration was completed five years after the 1883 eruption of Krakatoa, based on eyewitness accounts of the event. Illustration from The eruption of Krakatoa, and subsequent phenomena. Report of the Krakatoa Committee of the Royal Society (1888)

This gorgeous illustration was completed five years after the 1883 eruption of the volcanic island of Krakatoa, Indonesia, based on eyewitness accounts of the event.
Illustration from The eruption of Krakatoa, and subsequent phenomena. Report of the Krakatoa Committee of the Royal Society (1888)

(Editor’s note: Yes, we should be calling the still-active volcano Krakatau, but for historic consistency’s sake, we’re going to stick with Krakatoa for our purposes here.) 

Discussion Questions

 

  • According to the Nautilus article, the 1883 eruption of Krakatoa was the loudest sound in recorded history. But, powerful as Krakatoa was, it was far from the most powerful volcano in history. Why do you think the eruption of the Yellowstone Supervolcano—much more explosive than Krakatoa—didn’t make more noise?
    • It probably did. The key words in the first statement is recorded history. People weren’t measuring barometric pressure 2.2 million years ago, when Yellowstone went boom. (Don’t worry, it will boom again. Read more about it here.)

 

  • Take a look at the remarkable video above, which records a volcanic eruption and its resulting sound. Why can we (and videographers on the boat) see the eruption before we hear it?
  • Watch the video at about 10-15 seconds. We see a bright “halo” quickly moving above the volcano. What exactly are we seeing here?
    • What we’re seeing is a shock wave creating clouds by forcing molecules of water vapor together as the shock wave passes through the air. According to the Nautilus article, “When the volcano erupts, it produces a sudden spike in air pressure; you can actually watch as it moves through the air, condensing water vapor into clouds as it travels.”

 

  • In 1883, meteorologists in Europe, Asia, and Australia used barometers to track the blips in air pressure associated with the eruption at Krakatoa. Do you think these were blips of unusually high air pressure or low air pressure? What instruments do you think volcanologists and other scientists use to record volcanic sounds these days? Take a look at this page from Oregon State for some help.
    • The 1883 barometers were definitely recording blips of high atmospheric pressure, as the eruption’s shock wave shoved air molecules closer together (increasing their density and pressure).
    • According to Oregon State, scientists use microphones and hydrophones (underwater microphones) to record volcanic sounds. These instruments can record sounds audible to human ears as well as infrasound data—sound waves with a frequency so low that people can’t hear them. Of course, scientists and amateur meteorologists around the world still rely on barometers to measure air pressure. Read more about barometers here—better yet, make your own.

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TEACHERS’ TOOLKIT

Nautilus: The Sound So Loud That It Circled the Earth Four Times

This Day in Geographic History: Krakatoa Erupts

University of Oregon: Volcano Sounds

NG encyclopedia: barometer

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  5. Reblogged this on fsinnovations and commented:
    Dear FSI Friends,
    An introduction to Edie, the Blogger…
    This article is the sort that captures my sometimes,.. (OK, often, geeky) imagination and makes me wonder what others might think about the connections between the natural and cultural world. I wonder about such subjects as sound waves. Moreover, and in particular, this article prompts me to think of connections between content areas that might spark a green fuse in FSI scholars, both teachers and students, to think creatively, critically, and contextually. It certainly makes me want to dig deeper into the known and unknown field of WAVES and it makes me even more appreciative of the Franklin School of Innovation’s commitment to Deeper Learning. If students are interested in diving into this study, please let me know! I love to learn and I suspect our fantastic Science, Social Studies, and Math faculty crews at FSI would help me facilitate a future expedition into The Science, Measurement, and Mysteries of WAVES.

    Like

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