Earthquake nucleation characteristics revealed by the effect of short-and-long-term stress variations on induced seismicity.

Mateo Acosta, Jean-Philippe Avouac, Jonathan D. Smith, Krittanon Sirorattanakul, Hojjat Kaveh, & Stephen J. Bourne

Published September 10, 2023, SCEC Contribution #13247, 2023 SCEC Annual Meeting Poster #156

Deterministic earthquake prediction remains elusive, but time-dependent probabilistic seismicity forecasting seems within reach thanks to the development of physics-based models relating seismicity to stress changes. Challenges include constraining the earthquake nucleation model and fault initial stress state. Here, we use the well-documented induced earthquakes from the Groningen gas field, where stress variations show two different characteristic timescales: a long-term trend and a short-term yearly seasonal variation with large amplitudes. Moreover, in this field, seismicity began 3 decades after production started. We first show that the induced seismicity has a strong seasonal component through improved seasonality detection methods (Schuster test & spectrum), and we propose a novel metric to quantify the nucleation model’s ability to capture the damped amplitude and the phase of the seismicity response to short-timescale (seasonal) stress variations. We then use the seismicity response to short-term stress variations to constrain the earthquake nucleation process and calibrate models for time-dependent forecasting of induced earthquakes. Remarkable agreements of modelled and observed seismicity are obtained when we consider (i) the initial strength excess accounting for the delay between the start of production and the start of seismicity, (ii) the finite duration of earthquake nucleation by using Rate-and-State friction, and (iii) the seasonal variations of gas production which constrain the short-timescale variations of seismicity response. Our method allows constraining the nucleation model parameters and initial strength excess, and their associated uncertainties, which are key elements needed for induced seismicity forecasting.

Key Words
Earthquake Nucleation, Seasonal stress change

Citation
Acosta, M., Avouac, J., Smith, J. D., Sirorattanakul, K., Kaveh, H., & Bourne, S. J. (2023, 09). Earthquake nucleation characteristics revealed by the effect of short-and-long-term stress variations on induced seismicity.. Poster Presentation at 2023 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Forecasting and Predictability (EFP)