Flagship Research Projects

WIND IconThe WIND projet aims to develop seismic imaging methods which are more specifically devoted to stationary-recording acquisitions involving sparse arrays of autonomous stations (ocean bottom seismometers or land stations). The fact that the receiver layout is fixed gives the necessary versatility to design acquisition geometries involving large source-receiver offsets and wide azimuths such that waves can interact with subsurface heterogeneities in a varied manner by trasmission, reflection and diffraction. The rich angular illumination of the subsurface resulting from these acquisition geometries provides a suitable framework for high-resolution multi-parameter imaging provided the imaging techniques manage to assimilate the information content of the seismic data. In this context, we develop the so-called Full Waveform Inversion (FWI) method that aims to reconstruct the subsurface properties with a wavelength resolution by minimizing a distance between the recorded and the simulated data.

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Slow slip events (SSE) are transient processes releasing stress at faults without significant earthquake. Their discovery about two decades ago in subduction zones demonstrates a complex dynamics of the megathrust controlled by spatially variable friction at the plate interface. While deep SSEs occurring downdip of highly locked areas have been extensively studied, other subduction zones highlight another transient process where slip occurs at the same depths as large earthquakes and is synchronous to intense micro-seismicity. We refer to this type of transient as S5 for Synchronous Slow Slip & Seismic Swarm, which is the focus of our proposal.

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Large subduction earthquakes occur just below densely populated coastal areas and are therefore the source of very high risks for these regions. Among them, South America is one of the most seriously threatened. Its western coast is formed all along by the longest and most active known subduction zone. This project focuses on the northern section of this subduction zone from Northern Ecuador to Northern Peru.
Anticipating the location of the next ruptures and their magnitude is of commensurate importance to properly anticipate the risks and hence to protect the populations. Until recently, the critical questions posed to the scientific community of ‘when, where, and how large will the next earthquakes be?’ have been addressed using characteristics of large past earthquakes as a proxy for the possible future events. In this project, we propose a complementary approach to modern strain and stress monitoring of active tectonic zones.