Abstract

Anthropogenic fluid injections at depth induce seismicity which is generally organized as swarms, clustered in time and space, with moderate magnitudes. While some similarities between swarms have already been observed, whether they are driven by the same mechanism is still an open question. Pore fluid pressure or aseismic processes are often proposed to explain observations, while recent models suggest that seismicity is triggered by fluid-induced aseismic slip. Using 22 natural and anthropogenic swarms, we observe that duration, migration velocity and total moment scale similarly for all swarms. This confirms a common driving process for natural and induced swarms and highlights the ubiquity of aseismic slip. We propose a method to estimate the seismic-to-total moment ratio, which is then compared to a theoretical estimation that depends on the migration velocity, the effective stress drop and the slip velocity. Our findings lead to a generic explanation of swarms driving process.