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Browsing by Author "Ntinalexis, Michail"

Now showing 1 - 3 of 3
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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.