eprintid: 2208 rev_number: 9 eprint_status: archive userid: 6 dir: disk0/00/00/22/08 datestamp: 2019-04-08 14:11:00 lastmod: 2019-04-08 14:11:00 status_changed: 2019-04-08 14:11:00 type: article metadata_visibility: show creators_name: Leptokaropoulos, Konstantinos Michail creators_name: Staszek, Monika creators_id: kleptoka@igf.edu.pl creators_id: mstaszek@igf.edu.pl corp_creators: Institute of GeophysicsPolish Academy of SciencesWarsawPoland corp_creators: Institute of GeophysicsPolish Academy of SciencesWarsawPoland title: Temporal response of magnitude distribution to fluid injection rates in The Geysers geothermal field subjects: MP2 subjects: RU1_1 subjects: SG divisions: SHEER divisions: IP13 full_text_status: none keywords: Injection-induced seismicity Magnitude distribution Geothermal fields Statistical seismology abstract: The influence of fluid injection rates on the magnitude distribution of the seismicity which occurred in the NW part of The Geysers geothermal site is studied here. A direct comparison between injection rate changes and b value response is attempted after appropriate selection of data subsets. Due to the relatively small sample (1121 events, corresponding to an average rate of ~ 0.45 events/day), we also aggregated seismic activity into two families corresponding to increasing and decreasing injection rates, respectively. The b values were calculated as a function of time lag related to the injection activity. In agreement with previous studies, we found a statistically significant direct relation between b values and injection rate changes, which occurred at a zero or very short time lag (from 0 to ~ 15 days). However, the b value changes are related to the slope (i.e., the second derivative of injection volume), instead of the absolute values of injection rates. The increasing injection rates correspond to b = 1.18 ± 0.06, whereas the decreasing injection rates correspond to b = 1.10 ± 0.05. The corresponding values estimated by the repeated medians technique are b = 1.97 ± 0.20 and b = 1.50 ± 0.13. Both differences are significant at 0.05 level. date: 2019 date_type: published publication: Acta Geophysica volume: 67 number: 1 publisher: Versita, Warsaw and Springer-Verlag Berlin Heidelberg pagerange: 327-339 id_number: doi:10.1007/s11600-018-0215-1 issn: 1895-6572 official_url: http://doi.org/10.1007/s11600-018-0215-1 access_IS-EPOS: limited owner: Publisher acknowledgments2: IS-EPOS_platform acknowledgments2: SHEER_project citation: Leptokaropoulos, Konstantinos Michail and Staszek, Monika (2019) Temporal response of magnitude distribution to fluid injection rates in The Geysers geothermal field. Acta Geophysica, 67 (1). pp. 327-339. DOI: https://doi.org/10.1007/s11600-018-0215-1