Stress Evolution Modeling of Multiple Induced Seismicity Sequences
Rosie Ries
Stanford University
- Date & Time
- Location
- In-person and online seminar via Microsoft Teams
- Host
- Rob Skoumal
- Summary
Understanding the behavior of induced earthquake sequences can provide insights into the mechanics of fault activation. Previous induced seismicity studies have suggested an important role for aseismic slip, pore fluid pressure diffusion, stress transfer, poroelastic effects and earthquake-to-earthquake triggering in the evolution of induced earthquake sequences. To gain further insight into the potential role of these mechanisms in driving induced seismicity, we applied stress evolution modeling to 73 induced sequences of >150 earthquakes in Oklahoma and Kansas for which it appears that a single fault is being activated. Across these sequences roughly a third of earthquakes were identified as occurring on portions of the fault that were destressed by previous earthquakes, while roughly a quarter of earthquakes occurred at locations where stress transfer from preceding earthquakes increased stress more than 1 MPa. The remaining earthquakes occurred at locations that are ambiguous in the sense that the stress change that was imparted by previous earthquakes is small. The fraction of each of these categories varies between individual sequences as well. Our analysis suggests that multiple processes are driving seismicity, and the observed variability in behavior suggests that the relative role of different driving mechanisms may vary as well even within a relatively limited geographic area.