Groningen Region Earthquake Risk Assessment

Arup was appointed by Nederlande Ardolie Maatschappij, NAM, in 2013 to carry out consultancy services in relation to the structural upgrading of buildings, as part of the NAM strategy to manage the risk associated with induced seismicity from gas extraction in the Groningen region of the Netherlands. Relatively small earthquakes, linked to the gas extraction, had caused some damage to buildings and were the subject of serious concern to local and Government officials and the public, since more than 150,000 buildings were located in the potentially affected area. Arup were asked to make an assessment of the likely consequences, in building damage and potential casualties, from a scenario earthquake of Magnitude 5 located within the extraction zone.

CAR worked with the Arup team, developing, largely using the data in the Cambridge Earthquake Impact Database, fragility curves for the most significant classes of building found in the area. These were used to develop estimates of the number of buildings which would be seriously damaged by the scenario earthquake, and the consequent likelihood of casualties (both to occupants of buildings and those in nearby public spaces), and to put in place a strategy for upgrading buildings to ensure an acceptably low risk of human casualty.

The results were submitted to NAM in 2015, and helped to inform the Dutch Government’s decision about future gas extraction from the Groningen field. This project is believed to be the first in which an earthquake risk assessment has been used to inform an upgrading strategy to manage risks from induced seismicity.