On 22 July 2013, a series of earthquakes occurred in Dingxi, Gansu. The first quake struck at 07:45 China Standard Time with an epicenter located at the border of Min County and Zhang County. The magnitude of the initial earthquake was placed at Ms 6.6 by the China Earthquake Data Center with a focal depth of 20.0 kilometres (12 mi). It was measured at Mw 5.9 by the United States Geological Survey (USGS) and Mw  6.0 by the European Alert System. Another strong quake occurred about one hour later, measuring 5.6 magnitude by the USGS. As of 18:00 CST (10:00 UTC), 22 July 2013, 422 aftershocks had been recorded. The earthquakes were also felt in the nearby cities of Tianshui and Lanzhou in Gansu, as well as Xi'an, Baoji, and Xianyang in neighbouring Shaanxi.As of 23:00 CST, 23 July 2013, the earthquakes had caused at least 95 deaths, and more than 2,300 people were injured.