A statistical model for the seismicity rate of fluid‐injection‐induced earthquakes

Abstract

[1] We present a model for explaining the seismicity rate of fluid-injection-induced earthquakes. It is assumed that porepressure diffusion is the main triggering mechanism, and that the criticality of the medium is randomly distributed. Based on these and other poroelastic and stochastic assumptions, we derive equations for the induced seismicity rate during and after fluid injection. On this basis, a method is proposed for estimating hydraulic diffusivity using only the observed seismicity rate and an estimate of the activated seismogenic volume. This approach differs from previous methods in that an accurate hypocentral parameter catalog is not required. Numerical investigation of the proposed method indicates that it is relatively robust with respect to the activated seismogenic volume dimension estimate. Application of the technique to two Hot Dry Rock experiments, Fenton Hill and Soultz, produces diffusivity values that are consistent with independent estimates from prior investigations.

How faults wake up: The Guthrie-Langston, Oklahoma earthquakes

“…The envelope of this spreading zone of quiescence can also be approximated by a diffusion process with D = 0.012 m 2 /s. This back front (Parotidis and Shapiro, 2004) seems to exist also for later activity on other faults. The existence of a back front suggests that seismicity is driven by a stress perturbation that relaxes after it sweeps over the faults.…”

Earthquake Hydrology

“…Some cases of reservoir-induced seismicity, in particular those in which the seismicity lags changes in water level, have been attributed to changes in pore pressure p (e.g., do Nascimento et al, 2005;Ge et al, 2009;Talwani and Acree, 1985). Spatial migration of reservoir-induced seismicity (Talwani and Acree, 1985), seismicity induced by fluid injection (Parotidis and Shapiro, 2004;Shapiro et al, 2006;Tadokoro et al, 2000), and some aftershock sequences (e.g., Bosl and Nur, 2002;Hainzl, 2004;Miller et al, 2004;Nur and Booker, 1972) have been attributed to pore pressure diffusion. Spatial migration of reservoir-induced seismicity (Talwani and Acree, 1985), seismicity induced by fluid injection (Parotidis and Shapiro, 2004;Shapiro et al, 2006;Tadokoro et al, 2000), and some aftershock sequences (e.g., Bosl and Nur, 2002;Hainzl, 2004;Miller et al, 2004;Nur and Booker, 1972) have been attributed to pore pressure diffusion.…”

Control of pore fluid pressure diffusion on fault failure mode: Insights from the 2009 L'Aquila seismic sequence

“…case occurs only toward northwest. Another method for the computation of the hydraulic diffusivity using only the observed seismicity rate and the estimate of the activated seismogenic volume is that by Parotidis and Shapiro [2004]. Beyond a spherical geometry, which is obviously too simple for our case, the simplest approximation that can be used to represent our problem is 1-D, along a northerly direction where the migration of earthquakes is the fastest.…”