Why the large number of casualties?

1. The magnitude-6.5 earthquake that hit Longtoushan township of Ludian county was the largest one in Yunnan since 2000. The province is located on the collision belt of the boundary between the Eurasian and Indian tectonic plates.

2. The depth of the quake epicenter was considered shallow, at 12 kilometers. Other tremors near the surface in recent years include the Wenchuan earthquake in Sichuan province in 2010 in which 69,227 died, and the one that hit Yushu in Qinghai province in which 2,698 were killed.

3. The dense population. The average population density of Longtoushan township is 265 people per square kilometer, more than double of the number for the province. The average population density of nearby Yiliang, which was hit by a quake in 2012, is 205. About 80 residents died in the disaster.