By 10 pm on Friday, six people slightly injured in earthquakes had been promptly sent to hospital and discharged, with no deaths or collapsed houses reported, announced Dang Cheng, Party secretary and executive vice-mayor of Yinchuan, Ningxia Hui autonomous region, at a conference on Saturday.

During the conference, officials from Ningxia's earthquake agency noted that the frequent small seismic activities in Yinchuan recently are the results of normal stress release and adjustment of the area around the epic center. They are not indicating a big earthquake, though residents in the earthquake zone and nearby areas may still feel the impact of aftershocks in the next few days.

The region where the 4.8-magnitude and 4.6-magnitude quakes occurred on Thursday experienced an 8-magnitude earthquake in 1739, and the energy accumulated in the region in less than 300 years is not yet sufficient for another major earthquake to occur, which was also proved by the results of the active fault survey, said officials.

Officials also explained that seismic activity in a region tends to have ebbs and flows and Ningxia usually sees more earthquakes in winter and spring.

The two earthquakes on Thursday were the largest ones that have struck Ningxia since 1998. The energy accumulated in large earthquakes cannot be released all at once but will continue to be gradually released in the following smaller quakes. As the two earthquakes struck at the faulted basin in Yinchuan with a shallow depth, the unique geological conditions with thick sediment layers brought an amplifying effect on seismic waves, which made residents easier to feel the minor quakes clearly.

The public need to stay rationally vigilant to the quakes, as well as keep a normal life pace, said officials.