The 7.1-magnitude earthquake in northwest China affected an area of about 30,000 square kilometers and a population of 100,000, an official with the China Earthquake Administration said Sunday.

The earthquake has wreaked havoc in 12 village and townships in the counties of Yushu and Chengduo, Miao Chonggang, deputy head of the emergency response department at the China Earthquake Administration said.

The hardest-hit zone has an area of 900 square kilometers while a zone of 4,000 square kilometers was struck badly.

The China Earthquake Administration has made some revisions to some of the earthquake's parameters, Miao said.

The location of the epicenter has been updated to 33.2 degrees north and 96.6 degrees east from 33.1 degrees north and 96.7 degrees east.

Moreover, the epicenter depth has been modified to 14 kilometers from the previous 33 kilometers.

"The revisions don't affect the relief work and relevant decision making," Miao said.

Miao added the revisions were made based on data from global monitoring stations and meet international standards.

The 7.1-magnitude quake which struck the Tibetan Autonomous Prefecture of Yushu Wednesday morning has left at least 1,706 dead, 256 missing and 12,128 injured as of 10:00 a.m., Sunday.