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Shell Causes Earthquakes in the Netherlands

FROM OUR AUGUST 2005 SHELL NEWS ARCHIVE

BLOOMBERG: Shell Causes Earthquakes in the Netherlands

“Northern Netherlands Trembles as Gas Extraction Triggers Quakes: The entire area is sinking…”

Posted 30 August 2005

Northern Netherlands Trembles as Gas Extraction Triggers Quakes Aug. 29 (Bloomberg) — Arie de Langen says he never thought he’d have to worry about earthquakes in his northern Dutch village of Sappemeer.

Quakes were unheard of and homes in the dozens of towns and villages that dot the region were built with wooden frames and beamed roofs. Then a venture between Royal Dutch Shell Plc, Europe’s No. 2 oil company, and Exxon Mobil Corp. began extracting natural gas in the region, triggering land shifts.

Now de Langen and about 150,000 other people living atop the crumbling 900 square-kilometer (560 square-mile) gas field are concerned quakes could shake loose beams or bring down roofs. An Aug. 5 tremor was the nation’s second-strongest this year. The region had at least 30 quakes this year, putting it on course for the most tremors since records began in 1987.

“If they continue pumping gas, we’ll keep having these quakes,” said de Langen, who is retired. “All of this is a worry. I’m not happy.”

For the Netherlands, Western Europe’s third-largest producer of natural gas, ending the gas extraction may not be an option. About 60 percent of the power consumed in the country comes from gas-fueled generators, according to EnergieNed, the association of Dutch power companies.

“The gas is of enormous economic interest both nationally and in the North, which means the tremors are accepted by the local people,” said Hans Altevogt, a climate and energy campaigner with Greenpeace in Amsterdam.

Gas receipts are expected to net the Dutch state about 7.6 billion euros

($9.4 billion) this year, according to Jan van Diepen, an Economic Affairs Ministry spokesman.

Exploit More

The Shell-Exxon venture Nederlandse Aardolie Maatschappij BV says it plans to exploit the gas fields in the region for at least another 25 years. The Slochteren field, the Netherlands’ largest, originally had 2,700 billion cubic meters (8,900 billion cubic feet) of natural gas. About 1,100 billion cubic meters are untapped.

The venture, based in the northern town of Assen, has had to reinforce canals and dikes, and compensates people for damage to their homes. It has paid about 1 million euros in claims.

Around Groningen, the largest city in the north and the most densely populated area above the gas field, there are about 40 tremors a year that are caused by gas exploitation, said Reinier Treur, a spokesman for Nederlandse Aardolie. Groningen, with 180,000 people, was founded as a settlement in 1040 and has buildings dating back more than 400 years.

Deep Fissures

Four decades of gas extraction at the northern Slochteren field have created fissures as deep as 4 kilometers (2.5 miles) underground, causing the collapse of hundreds of tons of rock and quakes that crack walls.

“I expect it to get worse,” said Cobie Ketelaar, a resident of Sappemeer, site of the Aug. 5 tremor. “When the ground keeps sinking, you’ll keep having quakes.”

The entire area is sinking, says Bernhard Dost, an official at the Dutch meteorological society.

“We have 20 or 30 centimeters’ subsidence from gas pumping,” Pieter van Geel, the Dutch deputy minister for the environment, spatial planning and housing, said in an interview. That equates to an 8-to-12 inch drop in the ground’s surface.

The intensity of earthquakes is “very difficult” to predict, Dost said. A quake measuring 5 on the Richter scale might break walls and beams at the epicenter. Dost doesn’t expect a tremor on a scale that would level buildings.

Thunder and Trembling

“The most typical effects are a sound like thunder, and the shaking of floors and roofs,” he said.

The Netherlands’ most powerful recorded natural earthquake was in 1992, in the southern town of Roermond. It measured 5.8 on the Richter scale. While property was damaged, there were no injuries to people.

Most of the quakes caused by the gas-field extraction measure between 2 and

2.8 on the Richter scale, with the strongest recorded at 3.5, said Nederlandse Aardolie spokesman Treur. The Aug. 5 quake measured 2.2, enough to rattle glass and frighten residents.

“It was short but intense,” said Tineke Damhoff, a shop assistant. She thought an airplane had crashed nearby.

There have been 372 tremors from unnatural causes in the Netherlands since 1987, according to the Dutch Meteorological Society’s Web site.

For Sappemeer resident de Langen, the quakes spell a troubled retirement.

“My house has many cracks in the walls already,” he said.

To contact the reporter on this story:

Dale Crofts in Amsterdam at [email protected]

Last Updated: August 28, 2005 19:10 EDT

COMMENT BY A REGULAR CONTRIBUTOR, A FORMER SHELL EMPLOYEE

I read your article about the earthquakes in the Netherlands that were related to gas extraction.

Although the magnitude of these quakes is small in comparison to ‘natural’ quakes, the important thing to remember is that the damage done by an earthquake is very closely related to the depth at which the earthquake occurs. Shallow quakes, even if they are of low magnitude, can cause very serious damage. Very deep earthquakes, even if they are of high magnitude, often time cause little damage. The reason for this is that the ‘elastic’ energy released by the earthquake is naturally dissipated by rock through which it travels. The deeper the quake the greater the dissipation. Because this elastic energy travels as ‘waves’ this means that the great the dissipation the small the intensity (amplitude) of the wave. Big waves cause lots of shaking, little waves don’t shake all that much.

Because these gas fields in the Netherlands are very shallow even small magnitude earthquakes have the potential for causing damage. Like it or not, these quakes are caused by the withdrawal of the gas from thick rock reservoirs and as the gas pressure in these reservoirs is reduced the rock compresses. When it collapses suddenly the result is an earthquake. The consequence of reservior collapse is the subsidence and ground cracking and collapse seen at the surface.

Sometimes the ground around a gas or oil will collapse significantly, forming a large sinkhole. The term for this phenomenon is ‘cratering’.

Living near a large, shallow oil or gas field is no fun for property owners because the ground subsidence and attendant damage can cause property values to plummet. Of course, this results in economic hardship to the home or business owner. Sometimes it is possible to get compensation for these losses, sometimes not. Whatever the case may be the oil companies always make lots of money.

royaldutchshellplc.com and its sister websites royaldutchshellgroup.com, shellenergy.website, shellnazihistory.com, royaldutchshell.website, johndonovan.website, shellnews.net and shell2004.com are all owned by John Donovan. There is also a Wikipedia article.

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