Induced seismicity

The following documents and links provide access to information on induced seismicity resulting from mining operations. Reports and cover letters provided as part of the production plan procedure for the Groningen field can be found here. This does not include information on natural causes of seismicity occurring in the Netherlands.

Liability for damage is regulated in legislation and regulations and specifically in production and monitoring plans. The supervisory authority uses a risk analysis guideline on induced seismicity resulting from gas production as its assessment framework. The following links also provide information on induced events resulting from gas injection (nitrogen or methane) into the subsurface.

Risk analysis guideline on induced earthquakes resulting from gas production

In response to the Dutch Safety Board (Onderzoeksraad voor Veiligheid = OVV) report: ‘Earthquake risks in Groningen, the cabinet has stipulated that “safety risks should be explicitly analysed in mining companies’ production plans”. The cabinet thus wishes to ensure that safety is fully taken into account in the decision-making process. As a safety risks analysis entails more than just seismic hazards – which has been the focus until now – the Minister of Economic Affairs has asked the State Supervision of Mines (Staatstoezicht op de Mijnen = SodM) to develop a temporary guideline for analysing risks as a result of earthquakes induced by gas production (in Dutch) ahead of a definitive guideline on seismic hazards that is to be developed by operators and research institutes.

Basic principles
The temporary guideline is based on the results of existing studies. Wherever possible, the measures used in the guideline are based on quantifiable parameters found in existing analyses and sources of information. The guideline may be updated or superseded in future in response to new viewpoints and studies.

Delineation
The guideline covers the risk analysis of seismic hazards (=risk x effect), as required in hydrocarbon production plans (Mining Decree, Article 24.1p). It does not cover the broad risk assessment outlined in the proposed amendment to the Mining Act (increased importance and implementation of safety measures). Nor does it include the interpretation of risks (i.e. what the measures in this guideline mean in terms of, for instance, the possible extent and expected nature of the damage caused by ground movement; Mining Decree, Article 24.1q). The operator has to address this aspect separately in the production plan. With regard to measures to prevent or reduce ground movement (Mining Decree, Article 24.1r) or damage caused by ground movement ((Mining Decree 24.1s), the guideline only indicates the basic conditions for monitoring and risk management.

Application
The temporary guideline is documented in detail in a TNO report on the seismic risks of producing onshore gas fields in the Netherlands: Seismicity onshore gas fields in the Netherlands (in Dutch)

Documents on induced seismicity caused by gas production

TNO has carried out a number of studies, in cooperation with the Royal Netherlands Meteorological Institute KNMI, to delineate the seismic hazards of earthquakes resulting from gas production:

 

Documents on seismicity resulting from injection
At the request of NAM, TNO has carried out a literature study focusing on the occurrence of seismicity as a result of injection into the subsurface, the underlying physical mechanisms and their relevance to nitrogen injection. As no case of seismicity resulting from nitrogen injection into depleted fields is known, other similar subsurface injection activities have been studied.


Documents on seismicity resulting from gas storage
These documents relate to the Bergermeer gas storage facility.