BASEL, Switzerland - A geologist on trial for causing earthquakes while drilling for hot rocks to produce clean energy said yesterday that he was surprised by the strength of the most powerful temblor.
Markus Haering, who designed the geothermal project, rejected allegations that he deliberately damaged properties and said local people knew the risks.
“We had very little knowledge of seismicity’’ before starting to drill, Haering testified.
The deep drilling underground caused a series of earthquakes in 2006, including one of 3.4 magnitude, rattling residents of the northwest city of Basel. Project leader Geopower Basel has already paid around $9 million in compensation for cracked walls and other damage on properties near the experiment.
The project was suspended at the time and shut down last week after a risk analysis concluded that more quakes could follow if the drilling continued.
The experiment aimed to be the world’s first to generate power commercially by boiling water on rocks 3 miles underground.
The Swiss efforts are being closely watched in the United States, where the Energy Department is sponsoring more than 120 geothermal energy projects in several states. A leading US company, AltaRock Energy, in September stopped drilling at one key development site north of San Francisco, citing drilling difficulties.