Many factors could worsen damage from earthquake

Active quake zone

Ludian county in Zhaotong, Yunnan province, is located in an active earthquake zone, and it has suffered three earthquakes stronger than magnitude-5 since 2003.

The first of those, on Nov 15, 2003, caused five deaths and injured 29, while the most recent before Sunday's, a magnitude-5.6 quake on Aug 10, 2004, resulted in four deaths and 594 injuries.