Emergency services in and around the northern Swiss city of Basel were flooded with calls on Tuesday, as tremors measuring 3.2 in the Richter scale shook the region. It was the latest in series of small earthquakes over the past month caused by the Swiss Deep Heat Mining project.

The geothermal project, which was launched in 1996 under the auspices of the Swiss Federal Office of Energy, involves drilling the country's first exploratory borehole and injecting pressurized water more than 5000 meters (16,400 feet) underground.

But that has caused the earth to move in what is normally an area of geological calm.

"The first time around, I was really scared," said Catherine Wuest, a shopkeeper in Basel. "It was like a rock fall and glasses were tinkling in the cupboard. I didn't know what was happening."

Man-Made Quakes

Jean Ueberschlag, the mayor of nearby Saint Louis in France, has written to Swiss authorities recently demanding that the project be halted.

"You don't have the right to play around with the safety of our populations," he said.

Geopower, the company heading the project, suspended drilling in December but the tremors continue. Local authorities in Basel are set to meet at the end of January to debate the project, which was supposed to provide heat and energy for thousands of home in Basel.

"We're a bit nervous of course because the experts can't tell us how many tremors we're in for," said Marc Keller, a spokesman for Basel's public works department.