Browsing by Author "Stafford, Peter J."

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    Capturing spatial variability in the regional Ground Motion Model of Groningen, the Netherlands
    Kruiver, Pauline P.; Pefkos, Manos; Rodriguez-Marek, Adrian; Campman, Xander; Ooms-Asshoff, Kira; Lavoue, Anais; Stafford, Peter J.; van Elk, Jan; Chmiel, Malgorzata (Cambridge University Press, 2022-08-17)
    Long-term exploration of the Groningen gas field in the Netherlands led to induced seismicity. Over the past nine years, an increasingly sophisticated Ground Motion Model (GMM) has been developed to assess the site response and the related seismic hazard. The GMM output strongly depends on the shear-wave velocity (V ( S )), among other input parameters. To date, V ( S ) model data from soil profiles (Kruiver et al., Bulletin of Earthquake Engineering, 15(9): 3555-3580, 2017; Netherlands Journal of Geosciences, 96(5): s215-s233, 2017) have been used in the GMM. Recently, new V ( S ) profiles above the Groningen gas field were constructed using ambient noise surface wave tomography. These so-called field V ( S ) data, even though spatially limited, provide an independent source of V ( S ) to check whether the level of spatial variability in the GMM is sufficient. Here, we compared amplification factors (AF) for two sites (Borgsweer and Loppersum) calculated with the model V ( S ) and the field V ( S ) (Chmiel et al., Geophysical Journal International, 218(3), 1781-1795, 2019 and new data). Our AF results over periods relevant for seismic risk (0.01-1.0 s) show that model and field V ( S ) profiles agree within the uncertainty range generally accepted in geo-engineering. In addition, we compared modelled spectral accelerations using either field V ( S ) or model V ( S ) in Loppersum to the recordings of an earthquake that occurred during the monitoring period (M-L 3.4 Zeerijp on 8 January 2018). The modelled spectral accelerations at the surface for both field V ( S ) and model V ( S ) are coherent with the earthquake data for the resonance periods representative of most buildings in Groningen (T = 0.2 and 0.3 s). These results confirm that the currently used V ( S ) model in the GMM captures spatial variability in the site response and represents reliable input for the site response calculations.
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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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    Hybrid broadband ground motion simulation validation of small magnitude earthquakes in Canterbury, New Zealand
    Lee, Robin L.; Bradley, Brendon A.; Stafford, Peter J.; Graves, Robert W.; Rodriguez-Marek, Adrian (2020-05)
    Ground motion simulation validation is an important and necessary task toward establishing the efficacy of physics-based ground motion simulations for seismic hazard analysis and earthquake engineering applications. This article presents a comprehensive validation of the commonly used Graves and Pitarka hybrid broadband ground motion simulation methodology with a recently developed three-dimensional (3D) Canterbury Velocity Model. This is done through simulation of 148 small magnitude earthquake events in the Canterbury, New Zealand, region in order to supplement prior validation efforts directed at several larger magnitude events. Recent empirical ground motion models are also considered to benchmark the simulation predictive capability, which is examined by partitioning the prediction residuals into the various components of ground motion variability. Biases identified in source, path, and site components suggest that improvements to the predictive capabilities of the simulation methodology can be made by using a longer high-frequency path duration model, reducing empirical V-s30-based low-frequency site amplification, and utilizing site-specific velocity models in the high-frequency simulations.
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    Liquefaction Hazard in the Groningen Region of the Netherlands due to Induced Seismicity
    Green, Russell A.; Bommer, J. J.; Stafford, Peter J.; Maurer, B. W.; Kruiver, P. P.; Edwards, B.; Rodriguez-Marek, Adrian; de Lange, Ger; Oates, S. J.; Storck, T.; Omidi, P.; Bourne, S. J.; van Elk, J. (2020-08-01)
    The operator of the Groningen gas field is leading an effort to quantify the seismic hazard and risk of the region due to induced earthquakes, including overseeing one of the most comprehensive liquefaction hazard studies performed globally to date. Due to the unique characteristics of the seismic hazard and the geologic deposits in Groningen, efforts first focused on developing relationships for a Groningen-specific liquefaction triggering model. The liquefaction hazard was then assessed using a Monte Carlo method, wherein a range of credible event scenarios were considered in computing liquefaction damage-potential hazard curves. This effort entailed the use of a regional stochastic seismic source model, ground motion prediction equation, site response model, and geologic model that were developed as part of the broader regional seismic hazard assessment. No to minor surficial liquefaction manifestations are predicted for most sites across the study area for a 2475-year return period. The only sites where moderate surficial liquefaction manifestations are predicted are in the town of Zandeweer, with only some of the sites in the town being predicted to experience this severity of liquefaction for this return period. This work is made available under the terms of the Creative Commons Attribution 4.0 International license, https://creativecommons.org/licenses/by/4.0/.