Friday Seminar (22 November 2024) Alexandre Schubnel (ENS Paris/CNRS)

Title: Nucleation phase of earthquakes: from Mw-3 labquakes to the 700km deep Mw 7.8 Ogasawara earthquake

 

Abstract:
Since the early 1960s, earthquakes have been modeled, theoretically, numerically, and/or analogically, by a « spring-slider” type of system, whose dynamics depends on the friction law. An interesting property of these systems is the emergence of a nucleation phase, during which the mechanical instability (pre-slip) grows and accelerates to reach dynamic equilibrium. We will show that some scaling and statistical properties (premonitory Omori, migration, decreasing b-value, etc…) of this phase can be studied, in detail, at in-situ conditions of the Earth’s crust, on rocks in the laboratory. Finally, using a template matching approach, we will suggest that even (large) deep earthquakes seem to present some sort of nucleation phase.