eprintid: 2051 rev_number: 13 eprint_status: archive userid: 6 dir: disk0/00/00/20/51 datestamp: 2018-04-05 14:36:09 lastmod: 2018-09-10 08:18:57 status_changed: 2018-04-05 14:36:09 type: article metadata_visibility: show creators_name: Jagt, Lisanne creators_name: Ruigrok, Elmer creators_name: Paulssen, Hanneke corp_creators: Department of Earth Sciences, Utrecht University, Heidelberglaan 2, Utrecht, the Netherlands corp_creators: Department of Earth Sciences, Utrecht University, Heidelberglaan 2, Utrecht, the Netherlands; R&D Seismology and Acoustics, Royal Netherlands Meteorological Institute, De Bilt, the Netherlands corp_creators: Department of Earth Sciences, Utrecht University, Heidelberglaan 2, Utrecht, the Netherlands title: Relocation of clustered earthquakes in the Groningen gas field subjects: GN subjects: MP2_3 subjects: SHC subjects: SHU divisions: SHEER-4 full_text_status: none keywords: Groningen, induced seismicity, multiplet analysis, relocation abstract: Previous locations of earthquakes induced by depletion of the Groningen gas field were not accurate enough to infer which faults in the reservoir are reactivated. A multiplet analysis is performed to identify clusters of earthquakes that have similar waveforms, representing repeating rupture on the same or nearby faults. The multiplet analysis is based on the cross-correlation of seismograms to assess the degree of similarity. Using data of a single station, six earthquake clusters within the limits of the Groningen field were identified for the period 2010 to mid-2014. Four of these clusters were suitable for a relocation method that is based on the difference in travel time between the P- and the S-wave. Events within a cluster can be relocated relative to a master event with improved accuracy by cross-correlating first arrivals. By choosing master events located with a new dense seismic network, the relocated events likely not only have better relative, but also improved absolute locations. For a few clusters with sufficient signal-to-noise detections, we show that the relocation method is successful in assigning clusters to specific faults at the reservoir level. Overall, about 90% of the events did not show clustering, despite choosing low correlation thresholds of 0.5 and 0.6. This suggests that different faults and/or fault segments with likely varying source mechanisms are active in reservoir sub-regions of a few square kilometres. date: 2017 date_type: published publication: Netherlands Journal of Geosciences volume: 96 number: 05 publisher: Cambridge University Press pagerange: s163-s173 id_number: doi:10.1017/njg.2017.12 issn: 0016-7746 official_url: http://doi.org/10.1017/njg.2017.12 access_IS-EPOS: limited owner: Publisher acknowledgments2: SHEER_project citation: Jagt, Lisanne and Ruigrok, Elmer and Paulssen, Hanneke (2017) Relocation of clustered earthquakes in the Groningen gas field. Netherlands Journal of Geosciences, 96 (05). s163-s173. DOI: https://doi.org/10.1017/njg.2017.12