Abstract:

Models of induced and triggered seismicity fall into two categories: statistical and physics-based. Among physics-based models, the most widely accepted theory is the Coulomb rate-and-state model, originating from Dieterich's seminal work in 1994. This model's advantage lies in its ability to link stress changes and seismicity rates without making specific assumptions about the underlying processes. It has numerous applications, such as forecasting aftershocks, analyzing injection-induced seismicity, and quantifying the triggering of volcano-tectonic earthquakes. However, direct validation is challenging due to unknown heterogeneity and the necessity of interpreting stress changes through a model, meaning the stress changes are not exactly known.

To address this issue, we conducted small-scale experiments on red felser sandstone with an artificially created saw-cut fault. We applied a complex stress history to each sample and monitored the acoustic emissions, which are often considered representative of seismicity on very small scales. We varied the average loading rate and altered initial conditions, deviating from the assumptions of the original theory. In all cases, we found that the model fits the data with just two free parameters; however, one of these parameters deviates from the predicted theoretical value. These results highlight a correspondence between acoustic emission and natural earthquakes, providing validation for the Coulomb rate-and-state theory where stresses are precisely known. Additionally, they underscore aspects of the model where it may be lacking and not fully understood. Finally, we suggest that this model may be relevant to various engineering applications that use acoustic emissions for monitoring damage.

All are welcome.