scholarly journals Hazard and risk assessments for induced seismicity in Groningen

2017 ◽  
Vol 96 (5) ◽  
pp. s259-s269 ◽  
Author(s):  
Jan van Elk ◽  
Dirk Doornhof ◽  
Julian J. Bommer ◽  
Stephen J. Bourne ◽  
Steve J. Oates ◽  
...  

AbstractEarthquakes associated with gas production have been recorded in the northern part of the Netherlands since 1986. The Huizinge earthquake of 16 August 2012, the strongest so far with a magnitude of ML = 3.6, prompted reassessment of the seismicity induced by production from the Groningen gas field. An international research programme was initiated, with the participation of many Dutch and international universities, knowledge institutes and recognised experts.The prime aim of the programme was to assess the hazard and risk resulting from the induced seismicity. Classic probabilistic seismic hazard and risk assessment (PSHA) was implemented using a Monte Carlo method. The scope of the research programme extended from the cause (production of gas from the underground reservoir) to the effects (risk to people and damage to buildings). Data acquisition through field measurements and laboratory experiments was a substantial element of the research programme. The existing geophone and accelerometer monitoring network was extended, a new network of accelerometers in building foundations was installed, geophones were placed at reservoir level in deep wells, GPS stations were installed and a gravity survey was conducted.Results of the probabilistic seismic hazard and risk assessment have been published in production plans submitted to the Minister of Economic Affairs, Winningsplan Groningen 2013 and 2016 and several intermediate updates. The studies and data acquisition further constrained the uncertainties and resulted in a reduction of the initially assessed hazard and risk.

2021 ◽  
Vol 111 (5) ◽  
pp. 2595-2616 ◽  
Author(s):  
Danhua Xin ◽  
Zhenguo Zhang

ABSTRACT The improvement of ground-motion prediction accuracy is crucial for seismic hazard and risk assessment and engineering practices. Empirically regressed ground-motion prediction equations (GMPEs) are widely used for such purposes in decades. However, the inherent drawbacks of GMPEs, such as the ergodic assumption, lack of near-source observation, and insufficiency to deal with the spatial correlation issue, have motivated geophysicists to find better alternatives. Recent studies on well-recorded earthquakes have illustrated that physics-based simulation (PBS) methods can provide predictions that are comparable to or ever superior to GMPE predictions. The increasing interests in applying PBSs also pose the need to statistically compare these simulations against GMPE predictions or actual observations. We notice the limitations in previous studies focusing on the predictive capability check of PBS. This article is to illustrate how more reasonable check of PBS should be conducted. We consider GMPE works in generally judging the reasonability of PBS, but PBS has the advantage in characterizing the heterogeneity of ground motion of a moderate-to-large earthquake, especially when considering the complexities in fault geometry, regional stress fields, rock properties, surface of the Earth, and site effects. We would rather recommend that, in the future, different GMPEs are only used to preliminarily judge the reasonability of PBS scenarios; then the ground motions simulated by those reasonable PBS scenarios (not limited to one) are further used for the following seismic hazard and risk assessment.


2020 ◽  
Author(s):  
Stephen Bourne ◽  
Steve Oates

<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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