Our strategy is thus to map seismic activity in space and time as precisely as possible, involving various scale phenomena (the purpose of WP1 & WP2), construct the heterogeneous fault model (WP3) and study the sensibility and predictability (periodical behaviors and randomness) (WP4 & WP5). The episodic or periodic behaviors of tiny earthquakes, and slow slip behind, have been discovered in plate interfaces since two decades (Japan, California, Cascadia, etc.) and analyzed with possible stress perturbation and fault rheology. These events should be taken into account, in relation to the occurrence of the large earthquakes. We aim to 1) bring the synergy to understand better physically and statistically the variation of seismicity and 2) tackle the forecast of seismicity evolution due to small stress perturbations. The latter should play a role in the preparation process to the spontaneous rupture growth (triggering and precursory) before large earthquakes. The fully physical simulations are technically getting possible with continuous efforts. However, multi-scale factors of earthquakes over space and time should be integrated in this project.
We explore the merging points between mathematical model (randomness) and physical model (repeatedness) beyond the state-of-art. The originality, innovation and ambition of this project are first our attempt to reveal seismicity modulation both from field and laboratory data using sophisticated mathematical and seismic signal analysis methods and original laboratory equipment. Then, in numerical simulations (mathematical to fully-elastodynamics), we consider the randomness of heterogeneity and its evolution over various scales in both space and time in order to discuss about the magnitude-frequency relation of the seismicity.