Full-waveform event location and moment tensor inversion for induced seismicity

Willacy, C.; Dedem, Ewoud van; Minisini, Sara; Li, Junlun; Blokland, Jan-Willem; Das, Indrajit; Droujinine, Alexander

doi:10.1190/geo2018-0212.1

Cited by 60 publications

(63 citation statements)

References 31 publications

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“…In practice, the depth of the event hypocentre in the Groningen KNMI catalogue is assumed to be 3 km, coinciding with the depth of the Groningen reservoir layer. The extension of the seismic network in 2014 allowed for actual hypocentre locations to be derived Willacy et al 2019). Both studies observe that most induced earthquakes are indeed located within the reservoir layer showing a strong correlation between the earthquake location and the major NNE-SSE trending faults.…”

Section: Observed Seismicitymentioning

confidence: 99%

“…Both studies observe that most induced earthquakes are indeed located within the reservoir layer showing a strong correlation between the earthquake location and the major NNE-SSE trending faults. Willacy et al (2019) also derived focal mechanisms for the 100 events assessed. The results show clear consistent normal faulting mechanisms, in some cases associated with some oblique motion.…”

Section: Observed Seismicitymentioning

confidence: 99%

“…The horizontal resolution of the events in the Groningen catalogue is on the order of 0.5-1 km (see also Section 2.3; Dost et al 2017). However, several relocation studies have shown horizontal shifts of event locations by several kilometres Willacy et al 2019). This could significantly influence the interpretation of the cluster model results.…”

Section: Influence Of Location Errorsmentioning

confidence: 99%

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Clustering characteristics of gas-extraction induced seismicity in the Groningen gas field

Muntendam-Bos

2020

Geophysical Journal International

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SUMMARY The Groningen gas field in the north of the Netherlands is one of the largest gas fields in the world. Since the early 1990s induced seismicity has been recorded. The largest magnitude event observed so far was a Mw = 3.6 event at the town of Huizinge in 2012. The risk posed by the induced events urged the necessity to build comprehensive seismological models capable of explaining the spatial-temporal distribution of the recorded seismicity and evaluating the regional seismic hazard and risk. The link between the occurrence of the seismicity and pressure depletion due to the production of the gas has been firmly established. However, the construction of comprehensive seismological models as well as hazard assessment is complicated by the fact that it is difficult to distinguish between induced and clustered events (events triggered by stress transfer of preceding, neighbouring events). This paper explores the contribution of clustered populations (i.e. aftershocks) to the Groningen induced seismic catalogue based on a statistical methodology in the time–space–magnitude domain. Specifically, the distributions of space–time distances between pairs of nearest-neighbour earthquakes, referred to as cluster style, is analysed. The cluster style of the Groningen induced seismicity is found to be very diffuse and characterized by a very low proportion of fore-/aftershock sequences and swarms (∼5 per cent) and a large proportion of repeater events (∼10 per cent). In contrast to human-induced seismicity in other regions, the background seismicity rate of Groningen is very low. Temporal variations in background seismicity rates can be related to changes in fault loading rates induced by gas production. Furthermore, a significant amount of independent, coincidental events (events occurring very close in time, but long distances apart) are observed. As the large gas field is fully connected, loading of the faults occurs roughly simultaneously throughout the field. Hence, the statistical probability of events occurring very close in time, but spatially far apart is significantly larger than in areas of fluid-injection induced seismicity The significant amount of repeaters and coincidental events cause an overabundance of events at intermediate time- and space-distances. This is further enhanced by the larger location errors in the catalogue increasing the estimated space-distance for non-relocated events. The diffusivity due to this overabundance of events at intermediate time- and space-distances, and the low-proportion of true fore-/aftershocks renders the statistical method used incapable of deriving a proper mode-separation value. However, this is not unique to this method. Any statistical method aimed at resolving two populations will break down if one of the populations analysed is too small. Hence, it is advisable to use caution when distinguishing fore-/aftershocks sequences or swarms for induced seismicity where the relative proportion of clustered events may be significantly lower than for tectonic events. In addition, given the small proportion of clustering and the general uncertainty in earthquake statistics, the results of this paper indicate that a distinction for earthquake risk modelling in Groningen is unnecessary.

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Section: Observed Seismicitymentioning

confidence: 99%

Section: Observed Seismicitymentioning

confidence: 99%

Section: Influence Of Location Errorsmentioning

confidence: 99%

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Clustering characteristics of gas-extraction induced seismicity in the Groningen gas field

Muntendam-Bos

2020

Geophysical Journal International

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“…Error ellipsoid Willacy et al (2019) major milestones of quantitative location methods. With computational infrastructure available, the first practical applications of Geiger's least squares traveltime inversion (Geiger, 1912) became possible, leading to a rapid development of quantitative traveltime-based methods.…”

Section: Gas Extraction Induced Earthquakesmentioning

confidence: 99%

Recent Advances and Challenges of Waveform‐Based Seismic Location Methods at Multiple Scales

Tan

Schwarz

et al. 2020

Reviews of Geophysics

132

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Source locations provide fundamental information on earthquakes and lay the foundation for seismic monitoring at all scales. Seismic source location as a classical inverse problem has experienced significant methodological progress during the past century. Unlike the conventional traveltime‐based location methods that mainly utilize kinematic information, a new category of waveform‐based methods, including partial waveform stacking, time reverse imaging, wavefront tomography, and full waveform inversion, adapted from migration or stacking techniques in exploration seismology has emerged. Waveform‐based methods have shown promising results in characterizing weak seismic events at multiple scales, especially for abundant microearthquakes induced by hydraulic fracturing in unconventional and geothermal reservoirs or foreshock and aftershock activity potentially preceding tectonic earthquakes. This review presents a comprehensive summary of the current status of waveform‐based location methods, through elaboration of the methodological principles, categorization, and connections, as well as illustration of the applications to natural and induced/triggered seismicity, ranging from laboratory acoustic emission to field hydraulic fracturing‐induced seismicity, regional tectonic, and volcanic earthquakes. Taking into account recent developments in instrumentation and the increasing availability of more powerful computational resources, we highlight recent accomplishments and prevailing challenges of different waveform‐based location methods and what they promise to offer in the near future.

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“…This penalty function, used to measure the source image focusing property, is applied as an objective function to optimize the source image and the velocity model [18]. Besides the source location and velocity inversion, FWI is also used to invert for the moment tensor [19], [20]. Most of the work mentioned above is based on the conventional FWI [21].…”

mentioning

confidence: 99%