The deadliest day in human history 500 years ago

An earthquake in China about 500 years ago killed 100,000 people in just one day .

On the morning of January 23, 1556, a violent earthquake rocked Shaanxi Province, then considered the 'cradle of Chinese civilization.' The quake lasted only a few seconds , but it is estimated that it directly killed 100,000 people, and triggered a chain of landslides, sinkholes, fires, migrations, and famines, killing a total of 830,000 people.

The toll is not as high as the total number of deaths in major events such as World War I and World War II, or in pandemics, famines, and floods. But considering the extent of the damage done in a single day, the Shaanxi earthquake —also known as the Jiajing earthquake because it occurred during the reign of Emperor Jiajing of the Ming Dynasty—is considered the deadliest in history.

The 1556 Shaanxi earthquake killed an estimated 830,000 people. (Photo: History Collection).

Experts say the Shaanxi earthquake was around 8 - 8.3 magnitude . Although not the strongest earthquake in history, the disaster was classified as XI (Extremely Strong) on ​​the modified Mercalli scale , which measures the shaking of an earthquake.

Several stronger earthquakes occurred before and after. However, due to the geology and urban design of the place in 1556, the disaster caused unusually large damage to the neighboring cities of Huaxian, Weinan, and Huayin.

Given that the world population in 1556 was less than 500 million, the death toll from the Shaanxi disaster was almost certainly the largest single-day loss of life. The event may also hold the record for the highest death toll, although it is difficult to say for sure which day recorded the most deaths.

With more than 8 billion people living on Earth today, an average of 170,000 people die each day . The deadliest day of the war occurred on the night of March 9 and the morning of March 10, 1945, when the US military's Operation Meetinghouse bombing raid killed 100,000 people in Tokyo. Meanwhile, the two atomic bombs dropped on Hiroshima and Nagasaki in August of the same year killed 66,000 and 39,000 people, respectively.

The Yellow River Flood of 1931 was one of the largest natural disasters in history. The total number of fatalities remains a matter of debate, although some estimates suggest that more than 2 million people in central and eastern China died over a four-month period.

The Local Chronicle, which dates from 1177 BC, describes the devastation caused by the earthquake in detail, even asserting that mountains and rivers changed their positions . "In some places, the ground suddenly rose up to form new hills, or suddenly sank down and became valleys. In other places, a stream suddenly gushed out, or the earth split open and new water channels appeared. Tents, official houses, temples and walls suddenly collapsed ," the chronicle wrote.

Fissures opened in the ground more than 18 meters deep. In Huaxian, every building collapsed and about 60% of the population died in the area near the epicenter.

Loess landscape in Shaanxi province, China. (Photo: Wikimedia).

The epicenter was in the Wei River valley, which has a unique geology because it passes through the Loess Plateau in north-central China. The plateau is located southeast of the Gobi Desert and is made up of loess—a silt-like sediment created by the accumulation of dust blown in from the desert.

Today, people know that deadly landslides occur frequently on the plateau. But at that time, many houses were built directly into the soft loess cliffs, creating caves called yaodong . When the earthquake struck early in the morning, many of these artificial caves collapsed, burying people inside and causing landslides across the plateau. Furthermore, many of the city's buildings at that time were made of heavy stone, causing heavy damage when they collapsed.

There are three major faults running through the area: the North Huashan Fault, the Piedmont Fault, and the Weihe Fault . According to a 1998 geological analysis by a team from Peking University of the 1556 earthquake, the North Huashan Fault played an important role in the Shaanxi incident, as its scale and displacement were the largest.

The Shaanxi earthquake prompted experts to look into the causes and ways to reduce earthquake damage: stone structures were replaced with softer, more earthquake-resistant materials such as bamboo and wood.