The Great Shanxi Earthquake in 1556 in Seomseo Castle, Ming Dynasty
On the map, red is the current Shaanxi yellow is the area affected by the Shaanxi earthquake
The estimated magnitude is 80-83
There were about 830,000 casualties
Few people survived, from the earthquake area to 800 kilometers
At that time, 60 percent of the total population of the island province died
Even in the 1500s, there’s never been such a big damage in history
The reason for this damage was the housing problem 
At that time, cave-style houses called Yao-dong were popular in the earthquake-prone area
It’s a method of cutting a mountain into a cave and making a dwelling
This method was a direct hit to the earthquake