arXiv subjects

Mathilde Radiguet

Publications and source records attributed to Mathilde Radiguet.

3 recordsLinked to original sources

arXiv2024

Seismic swarms unveil the mechanisms driving shallow slow slip dynamics in the Copiap\'o ridge, Northern Chile

Like earthquakes, slow slip events release elastic energy stored on faults. Yet, the mechanisms behind slow slip instability and its relationship with seismicity are debated. Here, we use a seismo-geodetic deployment to document a shallow slow slip event (SSE) in 2023 on the Chile subduction. We observe dense, migrating seismic swarms accompanying the SSE, comprised of interface activity and upper plate splay faulting. Our observations suggest that the slow slip initiation is driven by structurally-confined fluid overpressure in the fluid-rich surroundings of a subducted seamount. This is consistent with an observed acceleration and expansion of the SSE after a $M_L=5.3$ earthquake likely triggering an increase in interface permeability. Historical earthquake swarms highlight the persistent structural control and recurrent nature of such slow slip events. Our observations provide insight into the interactions between slow slip and seismicity, suggesting they are controlled by creep on a fluid-infiltrated fault with fractally distributed asperities.

physics.geo-ph↗

arXiv2023

Slow slip detection with deep learning in multi-station raw geodetic time series validated against tremors in Cascadia

Slow slip events (SSEs) originate from a slow slippage on faults that lasts from a few days to years. A systematic and complete mapping of SSEs is key to characterizing the slip spectrum and understanding its link with coeval seismological signals. Yet, SSE catalogues are sparse and usually remain limited to the largest events, because the deformation transients are often concealed in the noise of the geodetic data. Here we present the first multi-station deep learning SSE detector applied blindly to multiple raw geodetic time series. Its power lies in an ultra-realistic synthetic training set, and in the combination of convolutional and attention-based neural networks. Applied to real data in Cascadia over the period 2007-2022, it detects 78 SSEs, that compare well to existing independent benchmarks: 87.5% of previously catalogued SSEs are retrieved, each detection falling within a peak of tremor activity. Our method also provides useful proxies on the SSE duration and may help illuminate relationships between tremor chatter and the nucleation of the slow rupture. We find an average day-long time lag between the slow deformation and the tremor chatter both at a global- and local-temporal scale, suggesting that slow slip may drive the rupture of nearby small asperities.

physics.geo-ph↗

arXiv2014

Linear elastic fracture mechanics predicts the propagation distance of frictional slip

When a frictional interface is subject to a localized shear load, it is often (experimentally) observed that local slip events initiate at the stress concentration and propagate over parts of the interface by arresting naturally before reaching the edge. We develop a theoretical model based on linear elastic fracture mechanics to describe the propagation of such precursory slip. The model's prediction of precursor lengths as a function of external load is in good quantitative agreement with laboratory experiments as well as with dynamic simulations, and provides thereby evidence to recognize frictional slip as a fracture phenomenon. We show that predicted precursor lengths depend, within given uncertainty ranges, mainly on the kinetic friction coefficient, and only weakly on other interface and material parameters. By simplifying the fracture mechanics model we also reveal sources for the observed non-linearity in the growth of precursor lengths as a function of the applied force. The discrete nature of precursors as well as the shear tractions caused by frustrated Poisson's expansion are found to be the dominant factors. Finally, we apply our model to a different, symmetric set-up and provide a prediction of the propagation distance of frictional slip for future experiments.

cond-mat.mtrl-sci↗