Experts: Erosion caused Mexico sinkhole, not water pumping

A study by experts in Mexico says that erosion of limestone bedrock and not excessive water pumping caused a huge sinkhole that appeared in farmland in central Mexico in late May

A huge sinkhole that appeared in a farm in central Mexico in late May was caused by erosion of limestone bedrock and not excessive water pumping, a study by experts said Sunday

Many residents in the Puebla state believed the sinkhole was the result of excessive ground water extraction by factories or a water bottling plant in the area. They had shut down a water bottling plant in the area earlier because they thought it was hurting water tables.

But Mexico’s National Water Commission said the cause of the crater was “a natural process of limestone being dissolved,” which can cause the soil on top to collapse. It said water table levels were stable and the aquifer was not over-exploited.

"There is no evidence that the cause of the sinkhole was water extraction," the commission said.

Puebla Gov. Miguel Barbosa said in June that if water extraction proved to be the culprit, he would cancel any pumping permits.

The bottom of the sinkhole is filled with water that appears to have strong currents, and experts say it is relatively warm, suggesting it comes from deep underground.

The sinkhole at the farm east of Mexico City has grown larger than a football field and swallowed a house. It also trapped two dogs that were rescued after several days on a ledge near the bottom of the 50-foot-deep (15-meter) hole.

The sinkhole is now over 400 feet (125 meters) across in some places, and may be 150 deep (45 meters) at its deepest point. It is hard to tell, because water fills much of the crater.