Spatiotemporal evolution of broadband seismological networks in the Netherlands and the added value of the NARS-DICTUM array

Passive seismic networks play critical roles in both seismicity monitoring and subsurface imaging. The seismic network in the Netherlands has continuously been expanded, both to monitor induced seismicity related to gas exploitation in the north and to monitor natural (tectonic related) earthquakes in the south of the country. Aside monitoring seismicity, the data delivered by the seismological networks is required for imaging the subsurface to improve our knowledge of the composition and structure. This serves as a crucial layer of information for decision-makers in regional planning, locating resources, and risk assessment regarding current and future projects utilising the Dutch subsurface. Over the years, there has been an increase in the number of geophones and accelerometers for monitoring mostly the high frequency seismic signals (induced seismicity) and imaging the near surface structure. However, the network of broadband seismometers for measuring tectonic events (usually lower frequency signals) and imaging deep subsurface is still limited. We describe an overview of previous temporary and permanent broadband seismometer deployments in the Netherlands, with a focus on the latest NARS-DICTUM array of 25 broadband seismometers, underscoring its design, instruments, installation, and some preliminary subsurface information delivered by the network.