94 houses damaged in S. China's cave-in Photo taken on May 15, 2012 shows a scene of the cave-in disaster in Liuzhou City, south China...

94 houses damaged in S. China's cave-in

Photo taken on May 15, 2012 shows a scene of the cave-in disaster in Liuzhou City, south China's Guangxi Zhuang Autonomous Region.

Photo taken on May 15, 2012 shows a cave-in pit in Liuzhou City, south China's Guangxi Zhuang Autonomous Region.

Photo taken on May 15, 2012 shows a scene of the cave-in disaster in Liuzhou City, south China's Guangxi Zhuang Autonomous Region.

Photo taken on May 15, 2012 shows a flying machine used to take aerial photos of the cave-in disaster areas in Liuzhou City, south China's Guangxi Zhuang Autonomous Region.

Backfilling work started in Liuzhou on Tuesday after experts said it is right time to backfill the pits caused by cave-ins, based on repeated surveys.

A geological disaster, which affected a total of 40,000 square meters of ground in Maohe village of Liuzhou on May 10, damaged 94 houses, including eight that collapsed.

The disaster was caused by several factors, including the dissolution of soluble bedrock layers -- which is how karst is shaped -- loose earth and the fluctuation of groundwater levels, according to the rescue headquarters.