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  • KNMI manages and provides access to a metadata inventory which contains information about KNMI seismic networks, stations and their instruments. Such information varies over time, for instance when new stations are deployed in a seismic network, when a new instrument is added to a station, or when orientations of sensors are estimated. The Inventory ChangeLog aims to inform stakeholders and users of the KNMI data about such changes.

  • This dataset represents expected location uncertainty of seismic events, when using sensors from the Netherlands seismic network and sensors just across the boarder in Belgium and Germany. The computation has been done over a grid covering the Netherlands, with a fixed source depth of 3 km. For each scenario event, the location probability density function has been determined, both as function of depth and as function of the horizontal coordinates. The assumption has been made that these probability density functions can be approximated as being (multivariate) normal distributions, such that they can be described with standard deviations. The uncertainty in the horizontal plane is parameterized with σ1 (S1), σ2 (S2) and θ (T). S1 is the standard deviation in the direction with maximum uncertainty, which occurs at a certain angle (T) with north. S2 is the standard deviation in the perpendicular direction with minimum uncertainty. In the vertical direction, the probability density function is computed at the most likely epicenter. The corresponding uncertainty is parameterized with SZ. Additionally, the azimuthal gap (AG) has been computed and is included in the dataset. This parameter describes how well the azimuthal coverage of stations is for event location. Details are described in the following technical report: https://cdn.knmi.nl/knmi/pdf/bibliotheek/knmipubTR/TR405.pdf.

  • The main seismic-network assessment parameter is magnitude of completeness, which has been computed over a grid covering the Netherlands. This parameter describes the spatial variation of the minimum magnitude for which almost every earthquake can be located. The location of an earthquake can be determined if the earthquake signal is detected on at least three sensors. Detection has been modeled using expected signal-to-noise levels. Noise levels are the actually recorded noise levels at stations from the Netherlands seismic network, and stations just across the border in Belgium and Germany. The signal levels have been modeled for sources at 3 km depth, using a newly calibrated P-wave ground-motion prediction equation. Details are described in the following technical report: https://cdn.knmi.nl/knmi/pdf/bibliotheek/knmipubTR/TR405.pdf.

  • ShakeMaps of Peak Ground Acceleration (PGA, in units of %g), Peak Ground Velocity (PGV, in units of cm/s), and Pseudo-Spectral Acceleration (PSA, in units of %g). The KNMI publishes ShakeMaps for induced earthquakes with magnitude bigger than 2.0 in the province of Groningen. A ShakeMap is a representation of the actual ground shaking produced by an earthquake. The ShakeMap represents a combination of automatically recorded strong motion values, in the accelerometer stations around the epicenter of the earthquake, with the Ground Motion Prediction Equations (GMPE), for the places where there are no stations around. This GMPE is specially developed for Groningen (V7). More information about ShakeMaps can be found at: http://www.knmi.nl/kennis-en-datacentrum/achtergrond/shakemaps-voor-groningen

  • Seismic datasets collected by NAM between 2013 and 2018 from downhole geophone arrays and flexible networks deployed in the Groningen area.

  • This dataset contains the seismic site-response zonation map for the Netherlands. The site-response (amplification) zonation map for the Netherlands is designed by transforming geological 3D grid cell models into five classes and an amplification factor (AF) is assigned to most of the classes. This site-response assessment, presented on a nationwide scale is important for a first identification of regions with increased seismic hazard potential, for example at locations with mining or geothermal energy activities. The site-response zonation map enables a prediction of site-response after a local earthquake as recommended in the following. It is very important to note that lithological information from geological voxel models is based on spatial interpolation and aimed at interpretations on regional scale. As a consequence, the presented site-response zonation map is also designed for regional interpretation, and not on individual grid cell scale. Furthermore, at locations with large subsurface heterogeneity, the interpretation should be handled with care. Additional local investigations measurements should be performed at sites of interest in order to assess the site-response in detail. For the map presented, the uncertainties to keep in mind are: first, the AF distribution along the classes, and secondly the uncertainty of the geological model used. The AF is designed to be added to an input seismic signal at a reference horizon with a shear-wave velocity of 500 m/s. This AF is class-dependent and covering only frequencies of 1-10 Hz. Furthermore, the AF does not reflect the maximum amplification that might occur within a smaller frequency band. Moreover, in the country's southern regions, a topographic effect may influence the site-response. It is important to mention that for now these areas are aggregated in Class V and require additional detailed site investigations for site-response assessment. The zonation map is based on digital geological models DGM, NL3D and GeoTOP (www.dinoloket.nl/subsurface-models) resampled to a regular grid (100m by 100m). The AF and associated uncertainty per class are available from the NetCDF metadata.