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Endless Thread

Best of Summer: The Loudest Sound

Mon Jul 24 2023
KrakatoaVolcanic EruptionGlobal ImpactNatural Disasters


The episode explores the massive explosion of Krakatoa in 1883, its impact on the atmosphere, and the global fascination with its sound. It delves into the scientific efforts to recreate the sound, the recording instruments used, and the media sensation it caused. The chapter also discusses the shock waves generated by the explosion, the shipping route in the Sunda Strait, and the devastating effects of tsunamis. It further explores the nature of volcanic eruptions, their sounds, and their global impact on climate and scientific understanding. The episode concludes with insights on the significance of studying Krakatoa for disaster response and global connectedness.


The Sound of Krakatoa Captivated the World

The deep sound felt across thousands of miles became a global media sensation, marking a special moment in human civilization.

Krakatoa's Explosion Had Unprecedented Force

The explosion's force was estimated to be equivalent to roughly 10,000 atomic bombs, leaving a lasting impact on the region and the world.

Volcanic Eruptions Create Destructive Sounds and Effects

Explosive eruptions produce violent explosions, pyroclastic flows, and intense noises from hot rocks interacting with water.

Krakatoa's Eruption Led to Global Discoveries

Studying Krakatoa contributed to the understanding of atmospheric currents, the discovery of the jet stream, and advancements in volcano monitoring and disaster response.

Krakatoa Connected People Through Natural Disasters

The eruption served as a moment of global connectedness, fostering learning and collaboration among people affected by natural disasters.


  1. The Sound of Krakatoa
  2. The Impact of Krakatoa's Explosion
  3. Volcanic Activity and Sounds
  4. Understanding Volcanic Eruptions
  5. The Global Impact of Krakatoa

The Sound of Krakatoa

00:01 - 09:44

  • In 1883, a massive explosion occurred in Krakatoa, Indonesia, causing a sound that was felt and heard across thousands of miles.
  • Scientists have tried to recreate the sound from the original instrument readings.
  • The sound was too deep for human hearing, but it became a global media sensation and marked a special moment in human civilization.
  • The early internet played a role in spreading information about the event.
  • The sound has fascinated many people for a long time and is constantly discussed on platforms like Reddit.
  • Instruments called barographs were used to capture the massive sound.

The Impact of Krakatoa's Explosion

09:26 - 18:38

  • On August 26th, 1883, Krakatoa's explosion generated shock waves that traveled around the world at least four times.
  • Barrographs recorded the explosion's effects on atmospheric pressure, with recordings as far away as London.
  • The British Royal Society estimated the force of the explosion to be equivalent to roughly 10,000 atomic bombs.
  • Krakatoa's eruptions were preceded by low rumbles and gassing sounds above what was typical for a day at sea.
  • The Sunda Strait, where Krakatoa is located, served as an important shipping route connecting Java with the Indian Ocean.

Volcanic Activity and Sounds

18:09 - 26:14

  • Volcanic activity in the 19th century impacted the water in the Sunda Strait, creating hydroacoustic waves.
  • Oliver, a volcanologist, is fascinated by volcano sounds and feelings.
  • The eruption of Krakatoa caused a massive black cloud of ash and four explosions that destroyed most of the islands.
  • Reports from distant locations described the sound as cannon or gunfire, matching the technology available at that time.
  • People mistook the sounds for thunder or attacks rather than a volcanic eruption.
  • The closer people were to Krakatoa, the more constant and distinct the sound became.
  • The eruptions also generated tsunamis between 100 and 135 feet tall that caused significant damage and displacement of ships and people.

Understanding Volcanic Eruptions

25:54 - 34:03

  • Magma contains gas that is released when pressure is released, leading to explosions.
  • Volcanoes with stickier magmas have slower gas release, resulting in explosive eruptions.
  • Explosive eruptions create pyroclastic flows of rock, ash, and gas at high temperatures.
  • Eruptions near water can produce intense noises from hot rocks interacting with water.
  • Ash fall can range from pitter-patter to a downpour depending on proximity to the eruption.
  • Witnesses described violent explosions, chains of fire, and choking sulfuric air.
  • Combining volcanic material with ocean water produces hydrochloric acid.
  • Eruptions caused burning rocks and mud showers on ships in the area.
  • The acoustic shadow zone phenomenon caused some people closer to the volcano not to hear the eruption sounds.
  • Tsunamis were triggered by explosive material entering the water.
  • Ships sailing through the strait after the eruption encountered large chunks of pumice.
  • Krakatoa's eruption was one of history's most devastating due to tsunamis and other effects.

The Global Impact of Krakatoa

33:34 - 40:38

  • The Krakatau volcanic eruption in 1883 was one of the most devastating in history, causing tsunamis and widespread destruction.
  • The eruption had global effects, including vivid red sunsets and a decrease in global temperature by 1.2 degrees Celsius.
  • Studying Krakatau led to the discovery of the jet stream and understanding of atmospheric currents.
  • Volcanology has brought significant benefits to the world, including volcano monitoring and improved disaster response.
  • Krakatau was a moment of global connectedness that helped people learn from each other about natural disasters.