Interplay of large-scale tectonic deformation and local fluid injection investigated through seismicity patterns at the Reykjanes Geothermal Field, Iceland

SUMMARY Occurrence of seismicity sequences as consequence fluid injection or extraction has long been studied and documented. Causal relations between parameters, such pressure, rates, total injected volumes injectivity, with derived rate, cumulative seismic moment, distance (RT-plot), b-values, etc. have derived. In addition, reservoir engineering parameters permeability/porosity flow types play a role together geology knowledge on fault fracture properties, influenced by the stress field different scales. this paper, we study observed related to water at Reykjanes Geothermal Field, Iceland. The region near well did not experience before start injection. However, continued activity during 3 months in 2015, resulting cloud about 700 events ranging magnitude from Mw 0.7 3.3. We re-located these using modified double-difference algorithm determined focal mechanism event subsets. Characteristic for site is that are bound 4 km point, moreover known faults seem act barrier fluids seismicity. Several repeating seismicity, defined bursts hypocenter migration velocities larger than d–1 their dominant direction propagation away point towards depths. within lack events, elevated b-values (∼1.5) consist many multiplets. Except coinciding onset injection, no correlation rates could be identified, neither hydraulic diffusivity models explain patterns. Comparison our results investigations background 1995 2019 swarm 1972 revealed similar patterns burst-like finally present conceptual model where propose represent release area close well, controlled an interplay local pore pressure changes extensional build up Ridge.