An earthquake preminilary measuring 6.6 magnitude on the Richter scale jolted an area bordering Min and Zhang counties, Dingxi city, Northwest China's Gansu province at 07:45 am, July 22, according to the China Earthquake Networks Center.

The epicenter, with a depth of 20 km, was monitored at 34.521 degrees north latitude and 104.23 degrees east longitude, said the center.

Four aftershocks measuring 3.0 to 3.9 magnitude on the Richter scale hit the region in 30 minutes.

No report on loss and casualty has been released.

The earthquake can be felt in Xi'an, Shaanxi province. A video clip uploaded to Sina shows water waving in a fish tank during the earthquake in Xi'an.