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- Title
Different Fault Response to Stress during the Seismic Cycle.
- Authors
Zaccagnino, Davide; Telesca, Luciano; Doglioni, Carlo
- Abstract
Featured Application: This article introduces a method to establish the state of mechanical stability of a fault system by analyzing modulations of seismic activity as a function of known perturbations, i.e., tidal stress. In addition to providing useful information about the physics of fault systems, our method can be applied to evaluate how unstable faults are with respect to additional stress, and therefore forecast their future slip.Mutatis mutandis, our approach can also be adopted in other fields where it is of paramount interest to assess the loading state of a physical system alternating stability to sudden breaking. Seismic prediction was considered impossible, however, there are no reasons in theoretical physics that explicitly prevent this possibility. Therefore, it is quite likely that prediction is made stubbornly complicated by practical difficulties such as the quality of catalogs and data analysis. Earthquakes are sometimes forewarned by precursors, and other times they come unexpectedly; moreover, since no unique mechanism for nucleation was proven to exist, it is unlikely that single classical precursors (e.g., increasing seismicity, geochemical anomalies, geoelectric potentials) may ever be effective in predicting impending earthquakes. For this reason, understanding the physics driving the evolution of fault systems is a crucial task to fine-tune seismic prediction methods and for the mitigation of seismic risk. In this work, an innovative idea is inspected to establish the proximity to the critical breaking point. It is based on the mechanical response of faults to tidal perturbations, which is observed to change during the "seismic cycle". This technique allows to identify different seismic patterns marking the fingerprints of progressive crustal weakening. Destabilization seems to arise from two different possible mechanisms compatible with the so called preslip patch, cascade models and with seismic quiescence. The first is featured by a decreasing susceptibility to stress perturbation, anomalous geodetic deformation, and seismic activity, while on the other hand, the second shows seismic quiescence and increasing responsiveness. The novelty of this article consists in highlighting not only the variations in responsiveness of faults to stress while reaching the critical point, but also how seismic occurrence changes over time as a function of instability. Temporal swings of correlation between tides and nucleated seismic energy reveal a complex mechanism for modulation of energy dissipation driven by stress variations, above all in the upper brittle crust. Some case studies taken from recent Greek seismicity are investigated.
- Subjects
ENERGY dissipation; DATA analysis; PHYSICS; TSUNAMI warning systems; NUCLEATION; DATA quality
- Publication
Applied Sciences (2076-3417), 2021, Vol 11, Issue 20, p9596
- ISSN
2076-3417
- Publication type
Article
- DOI
10.3390/app11209596