Sinkhole fears baseless
By Cyril Li |
June 7, 2010, Monday
|
Print Edition
Print Edition
SINKHOLES caused by ground surface collapses are normal occurrences and have nothing to do with earthquakes, experts said.
Several cases have been reported around the country, including two recently in the suburbs of Chengdu, capital of Sichuan Province.
The two sinkholes, one in Chengdu's Dayi District, the other in Chongzhou District, have caused widespread panic as villagers fear an earthquake is imminent.
However, local geologists found that the sinkhole in Dayi was caused by the over extraction of groundwater while the other was triggered by vibrations from nearby drilling and blasting work.
Experts from the province's geology monitoring station said the hole in Dayi was due to year-round extraction of groundwater, which loosened sand and gravel layers underneath the road. This eventually caused the sinkhole.
Also, the sinkhole in Chongzhou was due to vibrations caused by drilling and blasting in the vicinity, which loosened the gravel layer, allowing for water erosion.
With the groundwater level lowered, the weight of the road was too heavy and it collapsed.
"The two sinkholes are not earthquake precursors, but normal geological phenomenon," said Liu Junxian, a professor at the provincial Geo-Engineering Investigation Institute.
Meanwhile, an 8.3-meter wide and 6-meter deep sinkhole swallowed a section of expressway early on Friday in Zhejiang Province. No vehicles fell into it.
A preliminary probe attributed the collapse to karst topography.
Several cases have been reported around the country, including two recently in the suburbs of Chengdu, capital of Sichuan Province.
The two sinkholes, one in Chengdu's Dayi District, the other in Chongzhou District, have caused widespread panic as villagers fear an earthquake is imminent.
However, local geologists found that the sinkhole in Dayi was caused by the over extraction of groundwater while the other was triggered by vibrations from nearby drilling and blasting work.
Experts from the province's geology monitoring station said the hole in Dayi was due to year-round extraction of groundwater, which loosened sand and gravel layers underneath the road. This eventually caused the sinkhole.
Also, the sinkhole in Chongzhou was due to vibrations caused by drilling and blasting in the vicinity, which loosened the gravel layer, allowing for water erosion.
With the groundwater level lowered, the weight of the road was too heavy and it collapsed.
"The two sinkholes are not earthquake precursors, but normal geological phenomenon," said Liu Junxian, a professor at the provincial Geo-Engineering Investigation Institute.
Meanwhile, an 8.3-meter wide and 6-meter deep sinkhole swallowed a section of expressway early on Friday in Zhejiang Province. No vehicles fell into it.
A preliminary probe attributed the collapse to karst topography.
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