Unlocking the subsurface through knowledge controversy : how earthquakes induced by deep geothermal drilling have politicized the subsurface environment

The expansion of geothermal energy extraction from new geological contexts in France is prompting the development of ‘enhanced’ geothermal systems (EGS). However, the subsurface is a complex environment in which multiple uncertainties arise because of its confinement, both physical and in terms of access to knowledge and power, and which cannot easily be modified. We analyse how the seismicity induced by geothermal drilling in the Strasbourg region (France) has given rise to a public debate that has brought the subsurface out of its confinement and into political and civic arenas in particular. To attempt to understand how this occurred, we analysed interviews, press reports and grey literature, from which it transpired, firstly, that the cause of the earthquakes can be traced back to negligence and a culture of confidentiality on the part of the operating company, which underestimated certain models and failed to seek any outside opinion. Secondly, failures in the enforcement of subsurface regulations at the central government level were found to be due to a loss of expertise in the relevant government departments as a result of government reforms, which subsequently led to a reform of the mining code to re-establish a measure of control. Thirdly, we found that the earthquakes triggered the involvement of new interested parties, particularly from the civic and political spheres, which brought out issues relating to environmental and risk management through demands for more open access to knowledge about the subsurface. In effect, these earthquakes were the catalyst that enabled subsurface issues to break out of the expert sphere and into political and citizens’ arenas. However, what emerges is a process of politicization of subsurface environments that is still incomplete : the positions of the various players are open to question as regards governance, which, notwithstanding emerging demands, remains in the hands of central government and industrialists with little prospect of broader involvement.