Aftershock Triggering and Spatial Aftershock Zones in Fluid‐Driven Settings: Discriminating Induced Seismicity From Natural Swarms

Abstract

Fluid-driven seismicity typically refers to (minor) seismic events that (partially) involve fluid flows. Examples range from natural flows associated with rainfalls and volcanic eruptions to human-made contexts including wastewater injection wells, hydraulic fracturing, and geothermal power plants. Recently, anthropogenic sources have lead to an extraordinary surge of seismic activities in different parts of the United States (Ellsworth, 2013). The most extreme cases are reported in Oklahoma and southern Kansas where most seismic events are potentially linked to large-scale wastewater disposals. In this context, it is essential to distinguish between seismic events that are a direct or primary consequence of the fluid injections due to the associated increase in shear stress and/or pore pressure, for example, and those that are instead triggered from these or other seismic events due to static and/or dynamic stress changes, for example, commonly denoted as aftershocks. Identifying these and the specific underlying event-event triggering mechanisms has important consequences in terms of seismic hazard assessment, earthquake forecasting, and effective mitigation strategies.To what extent fluid-based anthropogenic seismicity bears similarities with its natural analog is an open question. Swarm-like features of induced seismicity associated with wastewater disposal and/or hydraulic

Limited earthquake interaction during a geothermal hydraulic stimulation in Helsinki, Finland

“…Broccardo et al, 2017;Mignan et al, 2017). The variations in seismicity rate are modulated by the hydraulic energy input rate, as expected for induced seismicity (Goebel et al, 2019;Langenbruch et al, 2011), but show no temporal clustering-in contrast to other fluid-driven settings (Karimi & Davidsen, 2021;Maghsoudi et al, 2018) as well as laboratory experiments and natural earthquakes (e.g., Davidsen & Kwiatek, 2013;Davidsen et al, 2021, and references therein). Neither the enhanced stressing rates due to fluid injection nor stress relaxation after the stimulation phases, nor the localization of seismicity within confined zones caused triggering.…”

Limited Earthquake Interaction During a Geothermal Hydraulic Stimulation in Helsinki, Finland

“…Broccardo et al., 2017; Mignan et al., 2017). The variations in seismicity rate are modulated by the hydraulic energy input rate, as expected for induced seismicity (Goebel et al., 2019; Langenbruch et al., 2011), but show no temporal clustering—in contrast to other fluid‐driven settings (Karimi & Davidsen, 2021; Maghsoudi et al., 2018) as well as laboratory experiments and natural earthquakes (e.g., Davidsen & Kwiatek, 2013; Davidsen et al., 2021, and references therein). Neither the enhanced stressing rates due to fluid injection nor stress relaxation after the stimulation phases, nor the localization of seismicity within confined zones caused triggering.…”

Short-term forecasting of Mmax during hydraulic fracturing

“…In the latter case, we remark that a change in S EFF sufficient to produce negative may be representative of a transition in seismic response and thus constitute a risk indicator. The observed cumulative seismic moment of earthquakes can include events that are induced by poroelastic stress, shear stress change due to mass change 8 , or possibly triggered by (dynamic or static) stress changes or afterslip arising from preceding events 43 , 44 . This could lead to a larger than predicted cumulative seismic moment, which only considers fluid induced arrested rupture.…”