The deadliest day.
There are many ways we humans have unleashed devastation on each other – nuclear weapons, pollution, the spread of deadly pathogens, just to name a few.
While it's hard to say with certainty, by many accounts the deadliest day in human history was actually the result of a natural disaster. On the morning of 23 January 1556, a massive earthquake rocked China's Shaanxi province, at the time considered the 'cradle of Chinese civilization'.
The quake only lasted a few seconds but is estimated to have directly killed 100,000 people, with the ensuing cascade of landslides, sinkholes, fires, migration, and famine killing an estimated total of 830,000 people.
Of course, that's nowhere near as high as the total death tolls of major events like WWI and WWI, or even pandemics, famines, or floods.
But when considering a single day of devastation, the Shaanxi earthquake – also known as the Jiajing earthquake because it struck under the reign of the Jiajing Emperor of the Ming dynasty – is widely considered the most fatal we know of. It's also listed as the deadliest recorded earthquake in history.
The event is only thought to have had a magnitude of 8.0 to 8.3. Many more powerful earthquakes have occurred both before and afterwards. But due to the geology and urban design of the area at the time, it caused disproportionately massive destruction to the surrounding cities of Huaxian, Weinan, and Huayin.
The Local Annals, which according to History.com date back to 1177 BCE, describe the destruction caused by the quake in rare detail.
A translated quote from the Annals claims that mountains and rivers changed places.
"In some places, the ground suddenly rose up and formed new hills, or it sank abruptly and became new valleys. In other areas, a stream burst out in an instant, or the ground broke and new gullies appeared. Huts, official houses, temples and city walls collapsed all of a sudden."
It's recorded that fissures opened up in the ground that were more than 18 meters (60 feet deep). ...
https://www.sciencealert.com/what-was-behind-the-deadliest-day-in-human-history