A strong and shallow magnitude 6.8 earthquake struck the far western region of Xinjiang yesterday, but in a sparsely populated area, the US Geological Survey said.
The tremor was only 12.5 kilometres deep, but hit in an extremely remote area about 270 kilometres east-southeast of Hotan, the USGS said.
The China Earthquake Networks Centre reported the quake's magnitude as 7.3. Another magnitude 5.7 tremor struck five minutes later - this one five kilometres deep - followed by a series of aftershocks of up to magnitude 4.2, it said.
Xinhua said no casualties were reported as of 7pm last night.
"We were at the office at the time and felt strong shaking, the windows were rattling," a reporter in Keriya county, near the epicentre told state broadcaster CCTV, adding that few people lived in the mountainous area and there were no reports yet of casualties or damage.
Sections of railway were temporarily suspended and the railway administration of Urumqi has decided to suspend the section from Hotan to Moyu station on the Kahe Railway, which links Kashgar and Hotan, for safety reasons, Xinhua reported.
A 5.4-magnitude quake hit the same place on Tuesday morning.
CCTV reported that Hotan was not seriously affected, while several people in the city said they felt less than a minute of shaking, Xinhua said, citing residents from nearby Yutian and Moyu counties.
"The earthquake lasted less than one minute; it was not strong, there are no buildings collapsed," said one resident.
An expert told CCTV that the affected area often experienced earthquakes, but was thinly populated, so the impact was likely to be limited.
President Xi Jinping and Premier Li Keqiang issued instructions on relief work soon after the quake, urging local authorities to be diligent in emergency management and seismic monitoring, Xinhua reported. Twenty rescue workers and inspectors were also sent to the scene by the central authorities, Xinhua reported.
A magnitude 7.3 earthquake struck the same county in March 2008, affecting 40,000 people, destroying 200 homes and causing 10 million yuan (HK$12.7 million) in damage.
A magnitude 6.6 earthquake in Sichuan province in the southwest killed about 200 people last April, five years after almost 90,000 people died when a huge tremor struck the same province.
Twin 5.6 and 5.9 magnitude quakes killed at least 95 people in the northwest province of Gansu last July.