The seismic monitoring network in Northern Switzerland has been considerably densified over the last 15 years (Plenkers 2014). The Nagra network operated by the Swiss Seismological Service (SED) currently includes 24 measurement stations, including three in shallow boreholes and one deep borehole station (Diehl et al. 2023, Spillmann et al. 2022). Using this system, all (micro)-seismic events with magnitude M_w > 1 can be detected and located reliably. Nagra also runs a permanent network of 11 Global Navigation Satellite System (GNSS) stations in and around the siting regions (Studer & Zanini 2013). The horizontal and vertical position of these stations is determined with high accuracy and temporal resolution, providing robust information on recent uplift and deformation. The seismic and geodetic monitoring systems substantially improved the understanding of the seismotectonic situation, providing input for the assessment of future tectonic movements (Section 6.2) and erosion (Section 6.4). In the three boreholes MAR1, STA3 and BOZ1, Nagra installed hydrogeological monitoring systems, adding to the pre-existing monitoring system in the BEN borehole (Longridge et al. 2024). This instrumentation aims to derive robust hydraulic heads in the Opalinus Clay, which cannot be deduced from hydraulic packer testing because of short-term drilling-induced effects and the short duration of the packer tests (see Section 5.6.5).