In Groningen last week, an earth tremor registering 3.0 on the Richter scale hit the village of Garrelsweer, rocking a dike and causing damage to houses.

It is the latest in a long line of earthquakes that regularly hit those living amid the Groningen natural gas fields, the largest in Europe. While the fields have been exploited for almost 50 years, earthquakes are now becoming more frequent, now averaging one a week compared to fewer than 20 a year before 2011.

The situation in Groningen

Those responsible for the drilling, the government and the Nederlandse Aardolie Maatschappij (NAM), a consortium that includes Royal Dutch Shell and Exxon Mobil Corp, concede that the earthquakes are caused by the extraction of natural gas from shale rocks deep below the Groningen region, an area that also has around 1.800 natural faults in its porous Rotliegend sandstone subsurface.

Up to 60 per cent of the 60.000 homeowners in the Groningen region have experienced earthquake damage to their homes and NAM is currently dealing with about 6.000 damage claims, 260 from last week alone.

A local anti-drilling activist group, De Groninger Bodem Beweging (GBB), says that many houses have thus become unsellable. They are also considering taking their complaint to the European Court of Human Rights, on the grounds their basic right to live without fear is being violated.

The need for gas

Nevertheless, the Netherlands is for many reasons unable to reduce the drilling. The government has made an estimated 250 billion euros since Groningen gas was discovered in the 1960s, with 14 billion euros in the last year alone. Without this revenue, the Dutch economy would be in serious trouble, with a deficit almost equal to that of Cyprus.

The gas is also vital to daily life in the Netherlands: almost everyone heats their houses and cooks their meals with Groningen gas. Finally, the government also has long-term contracts with other countries and reduction of supply might result in financial penalties.

For all these reasons, the government feels it can do little more than offer compensation to residents, despite some scientific advice and growing local pressure to reduce drilling.

How dangerous might it be?

The tremors of last week’s earthquake were measured by sensors on the Omenlander Dijk around 40 kilometres from the epicentre, which showed that the earthquake's impact was similar to truck loaded with 70 tons of rocks driving over the embankment. Local water authorities have raised fears of a possible flooding disaster if dikes nearer to the epicentre of a tremor are breached.

Last August there was a magnitude 3.4 tremor, which as it was higher than any expert had previously predicted, forced government ministers to commission an inquiry.

NAM spokesman Chiel Seined commented that while they always knew that earthquakes could occur, they are no longer sure what the new maximum magnitude could be. He also said people could count on being compensated by NAM for any damage to their property, but refused to rule out that someone might die as a result of an earthquake, stating "you can never exclude anything."