On the Behavior of Induced Seismicity

Abstract—The problem of induced seismicity has both practical and theoretical aspects. The practical aspect is related to the danger of induced seismicity. In a number of cases, the potential hazard from strong induced seismicity has prompted the cancellation of significant industrial projects. The theoretical aspect is related to the well-known paradox of seismicity that the earthquakes that rupture by the mechanism of ordinary brittle failure cannot occur at depths greater than a few tens of kilometers. This suggests that the physics of induced, typically shallow earthquakes can differ from the physics of most of the deeper events. Examples of a number of areas of induced seismicity both in the vicinity of large reservoirs and in the regions of extensive hydrocarbon and ore extraction are considered. A set of common trends is identified in all considered regions, with varying degrees of certainty. After the buildup of induced seismicity, even under a continuing strong anthropogenic impact, a declining trend is observed in seismicity rate. Furthermore, the analysis using the generalized vicinity of large earthquakes (GVLE) method revealed the closeness of the intensities of the fore- and aftershock process in the zones of induced seismicity. This contrasts with the patterns of ordinary seismicity, where aftershock activity process is typically much higher. It is hypothesized that the decay of induced seismicity is related to the unloading of the initial tectonic stresses, while the closeness of the intensities of the foreshock and aftershock processes suggests that the physical mechanism of induced shallow earthquakes differs from that of ordinary, deeper earthquakes.