The Krakatoa Eruption Produced the Loudest Sound in Human History, Bursting Eardrums 40 Miles Away
The Krakatoa eruption is one of the best known and well documented volcanic explosions of the modern era. It happened on Krakatoa Island, in the Sunda Strait between Java and Sumatra in the then Dutch East Indies (today’s Indonesia). Krakatoa, which had three volcanic peaks, started going off on the afternoon of August 26th, 1883, and reached a peak the next morning. By the time the eruptions stopped, most of Krakatoa Island and its surrounding archipelago had disappeared, having collapsed into a volcanic caldera. Tremors and other seismic activity then continued for a while, before silence fell months later.
The suddenness and intensity of the Krakatoa eruption might have been surprising, but the explosion itself was not, because there had been plenty of warnings. For years, Krakatoa had experienced intense seismic activity, with earthquakes whose tremors were felt as far away as Australia. Starting in May of 1883, three months before the dramatic explosion, Krakatoa began venting steam. Then it started hurtling columns of ash up to 20,000 feet into the air, and sounding off with pops that were loud enough to be heard in Jakarta, 100 miles away.
That initial activity went on for a week, then quieted down. It started again in mid June, with a thick black cloud that covered the area for a week. In the meantime, Krakatoa went off intermittently, spewing ash and throwing up volcanic debris that landed hundreds of miles away into the Indian Ocean. That activity did weird things to the tides in the surrounding region, and ships had to be moored with strong chains to resist the tide’s suddenly strong ebb and flow. By early August, Krakatoa was a desolate and abandoned island, covered in by nearly two feet of ash. All vegetation had died, leaving only tree stumps.
The final eruption began early in the afternoon of August 26. By 2PM, explosions were going off about every 10 minutes, and Krakatoa had spewed a 20 mile high ash cloud that was visible from far away. Ships up to 12 miles away reported a heavy ash fall, accompanied by bits of pumice up to 4 inches wide. By early evening, the volcanic activity had caused mini tsunamis, which hit the Sumatran and Javan coasts 25 miles away.
The climax happened the next morning, with two big eruptions, at 5:30 and 6:44AM on August 27th, that caused tsunamis. That was followed at 10:02AM by the loudest sound ever heard until then in recorded history: a cataclysmic explosion of about 180 decibels. That was equivalent to 15,000 Hiroshima bombs, and made the earlier eruptions seem like firecrackers by comparison. It was heard almost 2000 miles away in Perth, Australia, and 3000 miles away on the island of Rodrigues in the Indian Ocean. It also produced a tsunami about 100 feet high in places.
But the worst was yet to come. A fourth, and even more powerful eruption, occurred at 10:41AM. It was almost twice as loud as the earlier one, at 310 decibels. That was so loud that it ruptured eardrums 40 miles distant, and was clearly heard from 3100 miles away. A tsunami with a wall of water up to 120 feet high raced out. Ash was tossed 50 miles up into the sky by an explosion that produced a pressure wave that was recorded in barometers all over the world.
Recorded on global barometers not once, but seven times, as Krakatoa’s pressure wave raced around the planet for five days. It circled the earth and came back to the volcano, then continued on, again and again and again, still powerful enough to register on barometers everywhere on the planet as it circled the globe multiple times. The eruptions and resultant tsunamis killed at least 36,000 according to official Dutch estimates. Modern estimates put the casualty figures at up to 120,000.