Ground-Motion Attenuation, Stress Drop, and Directivity of Induced Events in the Groningen Gas Field by Spectral Inversion of Borehole Records

2020 ◽  
Vol 110 (5) ◽  
pp. 2077-2094 ◽  
Author(s):  
Gabriele Ameri ◽  
Christophe Martin ◽  
Adrien Oth
Keyword(s):  
Ground Motion ◽  
Destructive Interference ◽  
Rupture Directivity ◽  
Induced Earthquakes ◽  
Gas Field ◽  
Small Magnitude ◽  
Ground Motion Variability ◽  
Short Period ◽  
Groningen Gas Field ◽  
The Impact

ABSTRACT Production-induced earthquakes in the Groningen gas field caused damage to buildings and concerns for the population, the gas-field owner, and the local and national authorities and institutions. The largest event (ML=3.6) occurred in 2012 near Huizinge, and, despite the subsequent decision of the Dutch government to reduce the gas production in the following years, similar magnitude events occurred in 2018 and 2019 (ML=3.4). Thanks to the improvement of the local seismic networks in the last years, recent events provide a large number of recordings and an unprecedented opportunity to study the characteristics of induced earthquakes in the Groningen gas field and related ground motions. In this study, we exploit the S-wave Fourier amplitude spectra recorded by the 200 m depth borehole sensors of the G network from 2015 to 2019 to derive source and attenuation parameters for ML≥2 induced earthquakes. The borehole spectra are decomposed into source, attenuation, and site nonparametric functions, and parametric models are then adopted to determine moment magnitudes, corner frequencies, and stress drops of 21 events. Attenuation and source parameters are discussed and compared with previous estimates for the region. The impact of destructive interference of upgoing and downgoing waves at borehole depth on the derived parameters is also discussed and assessed to be minor. The analysis of the apparent source spectra reveals that several events show rupture directivity and provides clear observations of frequency-dependent directivity effects in induced earthquakes. The estimated rupture direction shows a good agreement with orientation of pre-existing faults within the reservoir. Our results confirm that rupture directivity is still an important factor for small-magnitude induced events, affecting the amplitude of recorded short-period response spectra and causing relevant spatial ground-motion variability.

Framework for a Ground-Motion Model for Induced Seismic Hazard and Risk Analysis in the Groningen Gas Field, The Netherlands

2017 ◽  
Vol 33 (2) ◽  
pp. 481-498 ◽  
Author(s):  
Julian J. Bommer ◽  
Peter J. Stafford ◽  
Benjamin Edwards ◽  
Bernard Dost ◽  
Ewoud van Dedem ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Quantitative Estimation ◽  
Epistemic Uncertainty ◽  
Induced Earthquakes ◽  
Gas Field ◽  
Small Magnitude ◽  
Ground Motion Model ◽  
Hazard And Risk ◽  
Groningen Gas Field

The potential for building damage and personal injury due to induced earthquakes in the Groningen gas field is being modeled in order to inform risk management decisions. To facilitate the quantitative estimation of the induced seismic hazard and risk, a ground motion prediction model has been developed for response spectral accelerations and duration due to these earthquakes that originate within the reservoir at 3 km depth. The model is consistent with the motions recorded from small-magnitude events and captures the epistemic uncertainty associated with extrapolation to larger magnitudes. In order to reflect the conditions in the field, the model first predicts accelerations at a rock horizon some 800 m below the surface and then convolves these motions with frequency-dependent nonlinear amplification factors assigned to zones across the study area. The variability of the ground motions is modeled in all of its constituent parts at the rock and surface levels.

scholarly journals Ground-motion networks in the Groningen field: usability and consistency of surface recordings

2019 ◽  
Vol 23 (6) ◽  
pp. 1233-1253 ◽  
Author(s):  
Michail Ntinalexis ◽  
Julian J. Bommer ◽  
Elmer Ruigrok ◽  
Benjamin Edwards ◽  
Rui Pinho ◽  
...  
Keyword(s):  
Ground Motion ◽  
Structural Response ◽  
Strong Motion ◽  
Induced Earthquakes ◽  
Gas Field ◽  
Shake Table Tests ◽  
Motion Models ◽  
General Terms ◽  
Hazard And Risk ◽  
Groningen Gas Field

Abstract Several strong-motion networks have been installed in the Groningen gas field in the Netherlands to record ground motions associated with induced earthquakes. There are now more than 450 permanent surface accelerographs plus a mobile array of 450 instruments, which, in addition to many instrumented boreholes, yield a wealth of data. The database of recordings has been of fundamental importance to the development of ground-motion models that form a key element of the seismic hazard and risk estimations for the field. In order to maximise the benefit that can be derived from these recordings, this study evaluates the usability of the recordings from the different networks, in general terms and specifically with regards to the frequency ranges with acceptable signal-to-noise ratios. The study also explores the consistency among the recordings from the different networks, highlighting in particular how a configuration error was identified and resolved. The largest accelerograph network consists of instruments housed in buildings around the field, frequently installed on the lower parts of walls rather than on the floor. A series of experiments were conducted, using additional instruments installed adjacent to these buildings and replicating the installation configuration in full-scale shake table tests, to identify the degree to which structural response contaminated the recordings. The general finding of these efforts was that for PGV and oscillator periods above 0.1 s, the response spectral ordinates from these recordings can be used with confidence.

scholarly journals Statistical physics models for aftershocks and induced seismicity

2018 ◽  
Vol 377 (2136) ◽  
pp. 20170397 ◽  
Author(s):  
Molly Luginbuhl ◽  
John B. Rundle ◽  
Donald L. Turcotte
Keyword(s):  
Induced Seismicity ◽  
Statistical Physics ◽  
Aftershock Sequence ◽  
Induced Earthquakes ◽  
Aftershock Activity ◽  
Gas Field ◽  
Natural Time ◽  
Parkfield Earthquake ◽  
Groningen Gas Field

A standard approach to quantifying the seismic hazard is the relative intensity (RI) method. It is assumed that the rate of seismicity is constant in time and the rate of occurrence of small earthquakes is extrapolated to large earthquakes using Gutenberg–Richter scaling. We introduce nowcasting to extend RI forecasting to time-dependent seismicity, for example, during an aftershock sequence. Nowcasting uses ‘natural time’; in seismicity natural time is the event count of small earthquakes. The event count for small earthquakes is extrapolated to larger earthquakes using Gutenberg–Richter scaling. We first review the concepts of natural time and nowcasting and then illustrate seismic nowcasting with three examples. We first consider the aftershock sequence of the 2004 Parkfield earthquake on the San Andreas fault in California. Some earthquakes have higher rates of aftershock activity than other earthquakes of the same magnitude. Our approach allows the determination of the rate in real time during the aftershock sequence. We also consider two examples of induced earthquakes. Large injections of waste water from petroleum extraction have generated high rates of induced seismicity in Oklahoma. The extraction of natural gas from the Groningen gas field in The Netherlands has also generated very damaging earthquakes. In order to reduce the seismic activity, rates of injection and withdrawal have been reduced in these two cases. We show how nowcasting can be used to assess the success of these efforts. This article is part of the theme issue ‘Statistical physics of fracture and earthquakes’.

scholarly journals The damaging character of shallow 20th century earthquakes in the Hainaut coal area (Belgium)

2021 ◽  
Author(s):  
Thierry Camelbeeck ◽  
Koen Van Noten ◽  
Thomas Lecocq ◽  
Marc Hendrickx
Keyword(s):  
Ground Motion ◽  
20Th Century ◽  
Focal Depth ◽  
Seismic Events ◽  
Late 20Th Century ◽  
Small Magnitude ◽  
Close Link ◽  
Epicentral Intensity ◽  
The 19Th Century ◽  
The Impact

Abstract. Shallow, light to moderate magnitude earthquakes in stable continental regions can have a damaging impact on vulnerable surface constructions. In the coal area of the Hainaut province in Belgium, a century of shallow seismic activity occurred from the end of the 19th century until the late 20th century. This seismicity is the second largest source of seismic hazard in northwestern Europe, after the Lower Rhine Embayment. The present study synthesises the impact and damage caused by this unique shallow seismicity. Reviewing intensity data provided in official macroseismic surveys held by the Royal Observatory of Belgium, press reports, and contemporary scientific studies resulted in a complete macroseismic intensity dataset. The strong shaking of five seismic events with moment magnitudes Mw around 4.0, which occurred on 3 June 1911, 3 April 1949, 15 December 1965, 16 January 1966, and 28 March 1967, locally caused widespread moderate damage to buildings corresponding to maximum intensity VII in the EMS-98 scale. For 28 earthquakes, detailed macroseismic maps were created. Our study highlights the capability of shallow, small-magnitude earthquakes to generate damage. Subsequently, using the Hainaut intensity dataset, we modelled a new Hainaut intensity attenuation law and created relationships linking magnitude, epicentral intensity and focal depth. Using these relationships, we estimated the location and magnitude of pre-1985 earthquakes that occurred prior to deployment of the modern digital Belgian seismic network. Estimated focal depths allowed discriminating between two different types of earthquakes. Some events were very shallow, only a few hundred metres deep, suggesting a close link to mining activities. Other earthquakes, including the largest and most damaging events, occurred at depths greater than 2 km but no deeper than 6 km, which would exclude a direct relationship with mining, but yet still might imply a triggering causality. This work results in a new updated earthquake catalogue including 123 seismic events. Our attenuation modelling moreover suggests that current hazard maps overestimated ground motion levels in the Hainaut area due to the use of inadequate ground motion prediction equations. Our Hainaut attenuation model is hence useful to evaluate the potential impact of current and future, e.g. geothermal energy, projects in the Hainaut area and other regions with a similar geological configuration.

scholarly journals Incorporating dwelling mounds into induced seismic risk analysis for the Groningen gas field in the Netherlands

2021 ◽  
Author(s):  
Pauline P. Kruiver ◽  
Manos Pefkos ◽  
Erik Meijles ◽  
Gerard Aalbersberg ◽  
Xander Campman ◽  
...  
Keyword(s):  
The Netherlands ◽  
Seismic Risk ◽  
Site Response ◽  
Gas Production ◽  
Fragility Functions ◽  
Gas Field ◽  
Amplification Factors ◽  
Reservoir Compaction ◽  
Groningen Gas Field ◽  
The Impact

AbstractIn 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.

scholarly journals Characterisation of ground motion recording stations in the Groningen gas field

2018 ◽  
Vol 22 (3) ◽  
pp. 605-623 ◽  
Author(s):  
Rik Noorlandt ◽  
Pauline P. Kruiver ◽  
Marco P. E. de Kleine ◽  
Marios Karaoulis ◽  
Ger de Lange ◽  
...  
Keyword(s):  
Ground Motion ◽  
Gas Field ◽  
Groningen Gas Field

scholarly journals Ground motion simulations of Hope fault earthquakes

2019 ◽  
Vol 52 (4) ◽  
pp. 152-171
Author(s):  
Ethan M. Thomson ◽  
Robin L. Lee ◽  
Brendon A. Bradley
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Sedimentary Basins ◽  
Velocity Model ◽  
Small Magnitude ◽  
Simulation Methodology ◽  
Motion Models ◽  
Stress Parameter ◽  
Short Period ◽  
Physics Based Simulation

This paper examines ground motions for a major potential Mw7.51 rupture of the Hope Fault using a physics based simulation methodology and a 3D crustal velocity model of New Zealand. The simulation methodology was validated for use in the region through comparison with observations for a suite of historic small magnitude earthquakes located proximal to the Hope Fault. Simulations are compared with conventionally utilised empirical ground motion models, with simulated peak ground velocities being notably higher in regions with modelled sedimentary basins. A sensitivity analysis was undertaken where the source characteristics of magnitude, stress parameter, hypocentre location and kinematic slip distribution were varied and an analysis of their effect on ground motion intensities is presented. It was found that the magnitude and stress parameter strongly influenced long and short period ground motion amplitudes, respectively. Ground motion intensities for the Hope Fault scenario are compared with the 2016 Kaik¯oura Mw7.8 earthquake, it was found that the Kaikoura earthquake produced stronger motions along the eastern South Island, while the Hope Fault scenario resulted in stronger motions immediately West of the near-fault region and similar levels of ground motion in Canterbury. The simulated ground motions for this scenario complement prior empirically-based estimates and are informative for mitigation and emergency planning purposes.

Statistical mechanics-based forecasting of induced seismicity within the Groningen gas field

2020 ◽  
Author(s):  
Stephen Bourne ◽  
Steve Oates
Keyword(s):  
Size Distribution ◽  
Induced Seismicity ◽  
Gas Production ◽  
Linear Functions ◽  
Fault System ◽  
Induced Earthquakes ◽  
Gas Field ◽  
Hazard And Risk ◽  
Stress Dependent ◽  
Groningen Gas Field

<p>Geological faults may fail and produce earthquakes due to external stresses induced by hydrocarbon recovery, geothermal extraction, CO<sub>2</sub> storage or subsurface energy storage. The associated hazard and risk critically depend on the spatiotemporal and size distribution of any induced seismicity. The observed statistics of induced seismicity within the Groningen gas field evolve as non-linear functions of the poroelastic stresses generated by pore pressure depletion since 1965. The rate of earthquake initiation per unit stress has systematically increased as an exponential-like function of cumulative incremental stress over at least the last 25 years of gas production. The expected size of these earthquakes also increased in a manner consistent with a stress-dependent tapering of the seismic moment power-law distribution. Aftershocks of these induced earthquakes are also observed, although evidence for any stress-dependent aftershock productivity or spatiotemporal clustering is inconclusive.</p><p>These observations are consistent with the reactivation of a mechanically disordered fault system characterized by a large, stochastic prestress distribution. If this prestress variability significantly exceeds the induced stress loads, as well as the earthquake stress drops, then the space-time-size distribution of induced earthquakes may be described by mean field theories within statistical fracture mechanics. A probabilistic seismological model based on these theories matches the history of induced seismicity within the Groningen region and correctly forecasts the seismicity response to reduced gas production rates designed to lower the associated seismic hazard and risk.</p>

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