A detailed seismic hazard assessment was carried out by Ove Arup & Partners in 2017 for the United Downs project. The assessment concluded that the seismicity induced during the Hot Dry Rock research programme in the 1980s is probably the best indicator of the seismicity to expect at United Downs; those events never reached a magnitude greater than 2 (see “what does seismic magnitude mean?” section). This was proven at United Downs, where injection testing caused a maximum event magnitude of 1.7 ML. However, production testing caused no seismicity, so no events are expected once the powerplant is operational.