“People who have illusions about China’s national strength have to wake up to the fact that many people still live in houses with similar conditions,” added the editorial.
Residents described how people ran out of buildings screaming as the two shallow quakes hit an hour apart around the middle of the day.
Television footage showed roads strewn with fallen bricks and rocks in Yunnan province’s Yiliang county, which appeared to be worst hit.
Authorities were sending thousands of tents, quilts and coats, and Premier Wen Jiabao was also heading to the area, Xinhua said.
Footage on state television network CCTV showed hundreds of people crowded into a sports field in Yiliang.
The US Geological Survey said the first quake struck at 11.20am (0320 GMT) at a depth of around 10 kilometres.
People took cover outside after the first quake and did not return indoors, said a man surnamed Xia reached by phone. “Lots of people are outside because they fear aftershocks,” he said.
“I was walking on the street when I suddenly felt the ground shaking beneath me,” posted one witness on Sina Weibo, a microblog similar to Twitter.
“People started rushing outside screaming, it still scares me to think of it now.”
The US Geological Survey said the first quake struck at 11.20am (0320 GMT) at a depth of around 10 kilometres (six miles), with the second quake around an hour later. They were followed by several aftershocks.