Quakes force Dutch to face gas-extraction issue

Professor stresses effects of tremors on public health

ZEERIJP, Netherlands — When Nienke Bastiaans fell in love with and bought a 17th-century thatched house in a rural Dutch village, one person warned about possible earthquakes due to natural gas extraction. “Nobody listened to him,” she said.

Now, 20 years later, thousands of homes in the northeastern Groningen province are facing reinforcement or even demolition because of hundreds of small tremors caused by decades of gas extraction. The scope of the problem is forcing the Dutch government to confront the prospect of a future without locally produced gas and lucrative gas tax revenue years earlier than previously expected.

Bastiaans and husband Tom Robinson just had the entire front wall of their home reinforced — paid for by the gas extraction company — and two chimneys replaced because of fears that another tremor could send them crashing through the roof.

The work was completed shortly before a shallow 3.4-magnitude earthquake on Jan. 8 directly under their village jolted the region and rekindled calls for the government to end gas extraction. The quake — the most powerful to hit the region in five years — triggered nearly 3,000 reports of property damage, including a long vertical crack in Zeerijp’s historic church tower.

Thousands marched in Groningen on Jan. 19 to protest the gas extractioncaused earthquakes.

The quakes occur because gas extraction lowers the pressure in a layer of porous sandstone about 2 miles below the Earth’s surface. This causes layers in the sandstone to be squashed together. If this happens along natural fault lines in the rock, it can cause tension and lead to sudden shifts.

“(The January quake) makes crystal clear the deep impact of the downside of gas extraction on Groningen and Groningers. The damage to their houses, the concerns, the feelings of insecurity, but also the lack clarity about when their damage will be dealt with,” said Gerald Schotman, director of the Netherlands Petroleum Co., known by its Dutch acronym NAM.

But the government can’t just order NAM to turn off the gas extraction machinery that dots the flat Groningen landscape. Some 90 percent of Dutch homes use the gas, and the government has long-term contracts to sell gas to neighboring countries.

Professor Tom Postmes of Groningen University says the effects of the quakes on public health are serious. “It revolves around stress,” he said. “We discovered (that people) who have damage to their home initially are not too badly affected. But over time — and especially if they have multiple instances of damage to their home — they tend to get very upset.” He said some 10,000 people have serious health issues caused by the stress.