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Browsing by Author "Bommer, Julian J."

Now showing 1 - 6 of 6
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    Characterisation of ground motion recording stations in the Groningen gas field
    Noorlandt, Rik; Kruiver, Pauline P.; de Kleine, Marco P. E.; Karaoulis, Marios; de Lange, Ger; Di Matteo, Antonio; von Ketelhodt, Julius; Ruigrok, Elmer; Edwards, Benjamin; Rodriguez-Marek, Adrian; Bommer, Julian J.; van Elk, Jan; Doornhof, Dirk (2018-05)
    The seismic hazard and risk analysis for the onshore Groningen gas field requires information about local soil properties, in particular shear-wave velocity (V (S)). A fieldwork campaign was conducted at 18 surface accelerograph stations of the monitoring network. The subsurface in the region consists of unconsolidated sediments and is heterogeneous in composition and properties. A range of different methods was applied to acquire in situ V (S) values to a target depth of at least 30 m. The techniques include seismic cone penetration tests (SCPT) with varying source offsets, multichannel analysis of surface waves (MASW) on Rayleigh waves with different processing approaches, microtremor array, cross-hole tomography and suspension P-S logging. The offset SCPT, cross-hole tomography and common midpoint cross-correlation (CMPcc) processing of MASW data all revealed lateral variations on length scales of several to tens of metres in this geological setting. SCPTs resulted in very detailed V (S) profiles with depth, but represent point measurements in a heterogeneous environment. The MASW results represent V (S) information on a larger spatial scale and smooth some of the heterogeneity encountered at the sites. The combination of MASW and SCPT proved to be a powerful and cost-effective approach in determining representative V (S) profiles at the accelerograph station sites. The measured V (S) profiles correspond well with the modelled profiles and they significantly enhance the ground motion model derivation. The similarity between the theoretical transfer function from the V (S) profile and the observed amplification from vertical array stations is also excellent.
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    A database of ground motion recordings, site profiles, and amplification factors from the Groningen gas field in the Netherlands
    Ntinalexis, Michail; Kruiver, Pauline P.; Bommer, Julian J.; Ruigrok, Elmer; Rodriguez-Marek, Adrian; Edwards, Ben; Pinho, Rui; Spetzler, Jesper; Hernandez, Edwin Obando; Pefkos, Manos; Bahrampouri, Mahdi; van Onselen, Erik P.; Dost, Bernard; van Elk, Jan (Sage Publications, 2023-02)
    A comprehensive database that has been used to develop ground motion models for induced earthquakes in the Groningen gas field is provided in a freely accessible online repository. The database includes more than 8500 processed ground motion recordings from 87 earthquakes of local magnitude M-L between 1.8 and 3.6, obtained from a large network of surface accelerographs and borehole geophones placed at 50 m depth intervals to a depth of 200 m. The 5%-damped pseudo-acceleration spectra and Fourier amplitude spectra of the records are also provided. Measured shear-wave velocity (V-S) profiles, obtained primarily from seismic Cone Penetration Tests (CPTs), are provided for 80 of the similar to 100 recording stations. A model representing the regional dynamic soil properties is presented for the entire gas field plus a 5 km onshore buffer zone, specifying lithology, V-S, and damping for all layers above the reference baserock horizon located at about 800 m depth. Transfer functions and frequency-dependent amplification factors from the reference rock horizon to the surface for the locations of the recording stations are also included. The database provides a valuable resource for further refinement of induced seismic hazard and risk modeling in Groningen as well as for generic research in site response of thick, soft soil deposits and the characteristics of ground motions from small-magnitude, shallow-focus induced earthquakes.
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    Developing a model for the prediction of ground motions due to earthquakes in the Groningen gas field
    Bommer, Julian J.; Dost, Bernard; Edwards, Benjamin; Kruiver, Pauline P.; Ntinalexis, Michail; Rodriguez-Marek, Adrian; Stafford, Peter J.; van Elk, Jan (2017-12)
    Major efforts are being undertaken to quantify seismic hazard and risk due to production-induced earthquakes in the Groningen gas field as the basis for rational decision-making about mitigation measures. An essential element is a model to estimate surface ground motions expected at any location for each earthquake originating within the gas reservoir. Taking advantage of the excellent geological and geophysical characterisation of the field and a growing database of ground-motion recordings, models have been developed for predicting response spectral accelerations, peak ground velocity and ground-motion durations for a wide range of magnitudes. The models reflect the unique source and travel path characteristics of the Groningen earthquakes, and account for the inevitable uncertainty in extrapolating from the small observed magnitudes to potential larger events. The predictions of ground-motion amplitudes include the effects of nonlinear site response of the relatively soft near-surface deposits throughout the field.
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    Ground-motion prediction models for induced earthquakes in the Groningen gas field, the Netherlands
    Bommer, Julian J.; Stafford, Peter J.; Ruigrok, Elmer; Rodriguez-Marek, Adrian; Ntinalexis, Michail; Kruiver, Pauline P.; Edwards, Benjamin; Dost, Bernard; van Elk, Jan (Springer, 2022-12)
    Small-magnitude earthquakes induced by gas production in the Groningen field in the Netherlands have prompted the development of seismic risk models that serve both to estimate the impact of these events and to explore the efficacy of different risk mitigation strategies. A core element of the risk modelling is ground-motion prediction models (GMPM) derived from an extensive database of recordings obtained from a dense network of accelerographs installed in the field. For the verification of damage claims, an empirical GMPM for peak ground velocity (PGV) has been developed, which predicts horizontal PGV as a function of local magnitude, M-L; hypocentral distance, R-hyp; and the time-averaged shear-wave velocity over the upper 30 m, V-S30. For modelling the risk due to potential induced and triggered earthquakes of larger magnitude, a GMPM for response spectral accelerations has been developed from regressions on the outputs from finite-rupture simulations of motions at a deeply buried rock horizon. The GMPM for rock motions is coupled with a zonation map defining frequency-dependent non-linear amplification factors to obtain estimates of surface motions in the region of thick deposits of soft soils. The GMPM for spectral accelerations is formulated within a logic-tree framework to capture the epistemic uncertainty associated with extrapolation from recordings of events of M-L <= 3.6 to much larger magnitudes.
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    Incorporating dwelling mounds into induced seismic risk analysis for the Groningen gas field in the Netherlands
    Kruiver, Pauline P.; Pefkos, Manos; Meijles, Erik; Aalbersberg, Gerard; Campman, Xander; van der Veen, Wim; Martin, Antony; Ooms-Asshoff, Kira; Bommer, Julian J.; Rodriguez-Marek, Adrian; Pinho, Rui; Crowley, Helen; Cavalieri, Francesco; Correia, Antonio A.; van Elk, Jan (2021-09-24)
    In order to inform decision-making regarding measures to mitigate the impact of induced seismicity in the Groningen gas field in the Netherlands, a comprehensive seismic risk model has been developed. Starting with gas production scenarios and the consequent reservoir compaction, the model generates synthetic earthquake catalogues which are deployed in Monte Carlo analyses, predicting ground motions at a buried reference rock horizon that are combined with nonlinear amplification factors to estimate response spectral accelerations at the surface. These motions are combined with fragility functions defined for the exposed buildings throughout the region to estimate damage levels, which in turn are transformed to risk in terms of injury through consequence functions. Several older and potentially vulnerable buildings are located on dwelling mounds that were constructed from soils and organic material as a flood defence. These anthropogenic structures are not included in the soil profile models used to develop the amplification factors and hence their influence has not been included in the risk analyses to date. To address this gap in the model, concerted studies have been identified to characterize the dwelling mounds. These include new shear-wave velocity measurements that have enabled dynamic site response analyses to determine the modification of ground shaking due to the presence of the mound. A scheme has then been developed to incorporate the dwelling mounds into the risk calculations, which included an assessment of whether the soil-structure interaction effects for buildings founded on the mounds required modification of the seismic fragility functions.
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    An integrated shear-wave velocity model for the Groningen gas field, The Netherlands
    Kruiver, Pauline P.; van Dedem, Ewoud; Romijn, Remco; de Lange, Ger; Korff, Mandy; Stafleu, Jan; Gunnink, Jan L.; Rodriguez-Marek, Adrian; Bommer, Julian J.; van Elk, Jan; Doornhof, Dirk (2017-09)
    A regional shear-wave velocity (V-S) model has been developed for the Groningen gas field in the Netherlands as the basis for seismic microzonation of an area of more than 1000 km(2). The V-S model, extending to a depth of almost 1 km, is an essential input to the modelling of hazard and risk due to induced earthquakes in the region. The detailed V-S profiles are constructed from a novel combination of three data sets covering different, partially overlapping depth ranges. The uppermost 50 m of the V-S profiles are obtained from a high-resolution geological model with representative V-S values assigned to the sediments. Field measurements of V-S were used to derive representative V-S values for the different types of sediments. The profiles from 50 to 120 m are obtained from inversion of surface waves recorded (as noise) during deep seismic reflection profiling of the gas reservoir. The deepest part of the profiles is obtained from sonic logging and V-P-V-S relationships based on measurements in deep boreholes. Criteria were established for the splicing of the three portions to generate continuous models over the entire depth range for use in site response calculations, for which an elastic half-space is assumed to exist below a clear stratigraphic boundary and impedance contrast encountered at about 800 m depth. In order to facilitate fully probabilistic site response analyses, a scheme for the randomisation of the V-S profiles is implemented.