Foreshocks and b Value: Bridging Macroscopic Observations to Source Mechanical Considerations

• Published in: Pure and applied geophysics Vol. 171; no. 10; pp. 2569 - 2580
• Main Authors: Avlonitis, M., Papadopoulos, G. A.
• Format: Journal Article
• Language: English
• Published: Basel Springer Basel 01.10.2014; Springer Nature B.V
• Subjects: Cellular; Constitutive relationships; Earth and Environmental Science; Earth Sciences; Earthquakes; Elastic properties; Exact solutions; Geophysics; Geophysics/Geodesy; Heterogeneity; Mathematical analysis; Mathematical models; Plate tectonics; Seismic activity; Seismic phenomena; Seismology; Softening; stochastic heterogeneity; Spring-block models; values; softening
• ISSN: 0033-4553; 1420-9136
• DOI: 10.1007/s00024-014-0799-6

Spring-block models, such as the Olami-Feder-Christensen (OFC) model, were introduced several years ago to describe earthquake dynamics in the context of self-organized criticality. With the aim to address the dependency of the seismicity style on source’s material properties, we present an analytical enrichment of a 2D OFC model. We conclude with an analytical expression which introduces, through an appropriate constitutive equation, an effective dissipation parameter a eff related analytically not only with the elastic properties of the fault plane, but also with stochastic structural heterogeneities and structural processes of the source through a gradient coefficient. Moreover, within the proposed formulation, the low b values experimentally observed in foreshock sequences can be modeled by a process of material softening in the seismogenic volume. To check our analytical findings, a cellular automaton was built-up whereas simulation results have verified the model’s predictions for the evolution of b in macroscopic records.