This is your morning Open Thread. Pour your favorite beverage and review the past and comment on the future.
Find the past “On This Day in History” here.
August 27 is the 239th day of the year (240th in leap years) in the Gregorian calendar. There are 126 days remaining until the end of the year.
On this day in 1883, The most powerful volcanic eruption in recorded history occurs on Krakatau (also called Krakatoa), a small, uninhabited volcanic island located west of Sumatra in Indonesia, on this day in 1883. Heard 3,000 miles away, the explosions threw five cubic miles of earth 50 miles into the air, created 120-foot tsunamis and killed 36,000 people.
Krakatau exhibited its first stirrings in more than 200 years on May 20, 1883. A German warship passing by reported a seven-mile high cloud of ash and dust over Krakatau. For the next two months, similar explosions would be witnessed by commercial liners and natives on nearby Java and Sumatra. With little to no idea of the impending catastrophe, the local inhabitants greeted the volcanic activity with festive excitement.
On 27 August four enormous explosions took place at 05:30, 06:44, 10:02, and 10:41 local time. The explosions were so violent that they were heard 3,500 km (2,200 mi) away in Perth, Western Australia and the Indian Ocean island of Rodrigues near Mauritius, 4,800 km (3,000 mi) away, where they were thought to be cannonfire from a nearby ship. Each was accompanied by very large tsunamis, which are believed to have been over 30 meters (100 ft) high in places. A large area of the Sunda Strait and a number of places on the Sumatran coast were affected by pyroclastic flows from the volcano.
The pressure wave generated by the colossal final explosion radiated from Krakatoa at 1,086 km/h (675 mph). It was so powerful that it shattered the eardrums of sailors on ships in the Sunda Strait and caused a spike of more than two and half inches of mercury in pressure gauges attached to gasometers in the Jakarta gasworks, sending them off the scale. The pressure wave radiated across the globe and was recorded on barographs all over the world, which continued to register it up to 5 days after the explosion. Barograph recordings show that the shockwave from the final explosion reverberated around the globe 7 times in total. Ash was propelled to a height of 80 km (50 mi).
The eruptions diminished rapidly after that point, and by the morning of August 28 Krakatoa was silent. Small eruptions, mostly of mud, continued through October, though further reports continued through February 1884. These reports were discounted by (Rogier) Verbeek.
The combined effects of pyroclastic flows, volcanic ashes and tsunamis had disastrous results in the region. There were no survivors from 3,000 people located at the island of Sebesi, about 13 km (8.1 mi) from Krakatoa. Pyroclastic flows killed around 1,000 people at Ketimbang on the coast of Sumatra some 40 km (25 mi) north from Krakatoa. The official death toll recorded by the Dutch authorities was 36,417, although some sources put the estimate at 120,000 or more.
Ships as far away as South Africa rocked as tsunamis hit them, and the bodies of victims were found floating in the ocean for weeks after the event. The tsunamis which accompanied the eruption are believed to have been caused by gigantic pyroclastic flows entering the sea; each of the four great explosions was accompanied by a massive pyroclastic flow resulting from the gravitational collapse of the eruption column.
In the aftermath of the eruption, it was found that the island of Krakatoa had almost entirely disappeared, except for the southern half of Rakata cone cut off along a vertical cliff, leaving behind a 250-metre (820 ft) deep caldera.
In the year following the eruption, average global temperatures fell by as much as 1.2 C (2.2 F). Weather patterns continued to be chaotic for years, and temperatures did not return to normal until 1888.
The eruption darkened the sky worldwide for years afterwards, and produced spectacular sunsets throughout the world for many months. British artist William Ashcroft made thousands of colour sketches of the red sunsets half-way around the world from Krakatoa in the years after the eruption.