Last night’s earthquake in the Eleveld gas field is the third in a month. “We have never seen three earthquakes in one month in that field before,” says Cynthia Heijne, spokesperson for the State Supervision of Mines (SodM). The last earthquake before this was in 2014.
Last night there was an earthquake with a magnitude of 2.2 on the Richter scale near Ekehaar. Last Monday’s earthquake near the same village had a magnitude of 1.3. In Hooghalen the ground shook at the beginning of October, with a magnitude of 1.9.
Earthquakes in that area are caused by gas extraction. According to the regulator, NAM is now analyzing how it is possible that three earthquakes occurred in a short time. Since October 15, the extraction of natural gas from the Eleveld has been halted due to planned maintenance.
The regulator believes that the tremors are not so much caused by the actual extraction of gas, but are “probably the result of pressure equalization”. Heijne explains: “The years of gas extraction have caused pressure differences in the Eleveld gas field. This pressure is now equalizing. The natural gas flows from places with high pressure to places with low pressure. This process also causes stresses on fractures. in the deep subsurface, which can lead to earthquakes.”
According to the SodM spokesperson, the earthquakes may be related. “If there is an earthquake in a gas field, tension is released at a fault,” she says. That tension can then ‘disappear’, but can also end up at another break in the field. “Such a fault may already be critically tense, which could cause another earthquake. We think this is related, but we want to wait for the NAM analysis because it is responsible.”
Shocks are regularly felt during Groningen earthquakes, but as far as we know, last night’s quake was barely noticed around Ekehaar. According to the State Supervision of Mines, this has everything to do with the soil type. The area around the Eleveld gas field is sandy soil, while Groningen has predominantly clay. An earthquake is less likely to be felt on sand than on clay.
It is not yet clear whether there is also damage to houses in the area. The Ministry of Economic Affairs calls on people who have suffered damage to report to the Mining Damage Committee.