Volcanic Thunder Recorded for the First Time

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When volcanoes erupt, they often do so thunderously. But until recently, scientists are unable to distinguish sounds of eruption from sounds of volcanic thunder. Only by cross checking map of volcanic lightning were they able to distinguish what on recording was volcanic thunder.

Two Types of Volcanic Lightning

Details of Discovery

  • Now, in new audio clips published in Geophysical Research Letters, scientists are revealing 1st recordings of phenomenon.
  • B/w December 2016 & August 2017, instruments captured sounds from several eruptions.
  • In addition to loud roar of eruptions, lightning strikes that spring from volcanic plumes create loud claps of thunder.
  • Crackling sound was identified using microphones set up to detect eruptions coming from Bogoslof volcano in Alaska՚s southwestern Aleutian Islands.
  • Over 8-month period, microphones picked up mixture of eruption booms & lightning cracks.
  • It wasn՚t until study published in 2016 that scientists even knew what caused volcanic lightning.

Reason for Volcanic Lightening

  • Similar to lightning that forms in clouds, volcanic lightning occurs when electricity flows b/w positively & negatively charged particles.
  • Unlike atmospheric lightning, lightning born from volcanoes forms much closer to ground, in plumes of eruption & unlike atmospheric lightning, volcanic lightning doesn՚t always move downward.
  • Result is series of jagged bolts of electricity that appear to jump out of volcano՚s mouth. Visually, it՚s one of most stunning shows put on by nature.

Difference between Volcanic Blasts and Thunder

  • In recordings published in study, sounds of thunder can be initially difficult to distinguish from sounds of eruption.
  • Volcanic blasts sound like low, deep rumblings, while thunder sounds more like brief clicks & pops.
  • During period monitored for study, eruptions sometimes produced plumes that towered more than 20,000 feet high.

Benefits of the Research

  • Be understanding how & when volcanic thunder cracks, scientists will be better predict size of plume coming off eruption.

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