Determining the impact of induced seismicity – a fully integrated modeling approach

Abstract:

While the concept of fluid-induced seismic activity has been studied over the last few decades, the increase in felt - and sometimes damaging - events over the last few years has escalated the need to be able to model the ongoing processes and forecast possible seismicity. For a complete estimate of the impact of a proposed fluid injection, it is important to include hazard estimates into the calculations. Here we introduce the combination of the RSQsim earthquake simulator and the RiskCat code.

The physics-based earthquake simulator RSQsim is based on rate-state friction and was originally designed to model large-scale scenarios, such as for example those for UCERF3. The creators recently added the possibility to account for pressure increases due to fluid injections within RSQsim. The knowledge about the pore-pressure distribution is added to the increase in stresses due to tectonic loading. We use the output of the RSQsim simulations as input for the RiskCat calculations in order to determine hazard rates.

Here we present calculations based on a fault set-up with realistic values found in the Southern San Joaquin Valley. The pore-pressure distributions needed for the input into RSQsim are calculated with the TOUGH code framework. Through TOUGH, we obtain complex pore-pressure time histories, based on realistic examples. By having these input values, we create a more realistic scenario of the expected seismic activity and the hazard levels. We propose that methods like this will be used in advance of fluid injections for prospective projects.