KUNMING -- A major aftershock measuring 4.7 degrees on the Richter scale on Tuesday jolted counties of Yanjin and Daguan in southwest China's Yunnan Province, injuring 16 people and destroying thousands of buildings.

The quake, which lasted about five seconds, occurred at 9 a.m. on Tuesday, local authorities said, adding that more aftershocks may hit the area in the next few days.

The tremor has destroyed some buildings in an elementary school in Yanjin County, forcing all students to move out of their classrooms.

Among the 16 injured, three are in critical condition.

Local governments are making efforts to prevent possible geological disasters triggered by the quake such as landslides and rockfalls in mountainous areas.

Two moderate earthquakes measuring over 5 degrees on the Richter scale hit the two counties on July 22 and August 25, killing over 20 people, injuring 100 others.

The quakes caused economic losses of 700 million yuan (87.5 million U.S. dollars), affecting more than 300,000 people.

Thousands of houses, mostly built on hillsides and vulnerable to natural disasters were toppled in the quakes, which forced the relocation of 45,520 people, according to the Ministry of Civil Affairs.