A geologist on trial for setting off home-wrecking earthquakes during experiments to produce clean energy has told a court he was surprised by the strength of the tremors.

But Markus Haering, who designed the geothermal project in Basel, Switzerland, rejected allegations that he deliberately damaged properties and said local people knew the risks.

Haering's company Geopower had been working with the authorities in Basel to try to convert the heat in deep-seated rocks into electricity.

The deep drilling underground caused a series of earthquakes in 2006, including one of 3.4 magnitude.

Haering could be sentenced to up to five years in prison. Geopower has paid around 9 million Swiss francs ($9 million) in compensation for cracked walls and similar damage on nearby houses and other buildings.

Haering said those involved had "very little knowledge of seismicity" before drilling began in the Petit-Huningue area of the city.

A verdict is expected next week.

Belfast Telegraph