Articles | Volume 23, issue 2
Research article
29 Apr 2016
Research article |  | 29 Apr 2016

Static behaviour of induced seismicity

Arnaud Mignan

Abstract. The standard paradigm to describe seismicity induced by fluid injection is to apply non-linear diffusion dynamics in a poroelastic medium. I show that the spatio-temporal behaviour and rate evolution of induced seismicity can, instead, be expressed by geometric operations on a static stress field produced by volume change at depth. I obtain laws similar in form to the ones derived from poroelasticity while requiring a lower description length. Although fluid flow is known to occur in the ground, it is not pertinent to the geometrical description of the spatio-temporal patterns of induced seismicity. The proposed model is equivalent to the static stress model for tectonic foreshocks generated by the Non-Critical Precursory Accelerating Seismicity Theory. This study hence verifies the explanatory power of this theory outside of its original scope and provides an alternative physical approach to poroelasticity for the modelling of induced seismicity. The applicability of the proposed geometrical approach is illustrated for the case of the 2006, Basel enhanced geothermal system stimulation experiment. Applicability to more problematic cases where the stress field may be spatially heterogeneous is also discussed.

Short summary
Induced seismicity is a concern for the industries relying on fluid injection in the deep parts of the Earth’s crust. At the same time, fluid injection sites provide natural laboratories to study the impact of increased fluid pressure on earthquake generation. In this study, I show that simple geometric operations on a static stress field produced by volume change at depth explains two empirical laws of induced seismicity without having recourse to complex models derived from rock mechanics.