Engineers halted an experiment to extract geothermal heat from deep below ground because a small earthquake occurred during the test in the nearby city of Basel, the Swiss news agency SDA said Saturday.
The tremor late Friday measured magnitude-3.4 and caused widespread fear, prompting about 1,000 calls to emergency services, but caused no injuries or serious damage, the agency said.
Managers apologized for any fears aroused by the mishap, which occurred after water was injected at high pressure into a 16,000-foot-deep (5-kilometer-deep) borehole, but said the experiment posed no danger, SDA reported.
The Basel public prosecutor launched an investigation into the government-subsidized project after the quake in the historic city, it said.
The $66.95 million experiment, known as “deep heat mining,” is designed to extract enough superheated water to drive a power plant providing electricity for 10,000 homes and heat for 2,700 others.