Missions

As part of the ERC project ABYSS ('Megathrust Faults Monitoring from Abyssal Distributed Acoustic Sensing'), we are looking to recruit a post-doctoral student to work on very low frequency signals recorded by Distributed Acoustic Sensing (DAS).
This project aims to explore the capabilities of DAS to detect transient tectonic deformations, such as slow earthquakes, in order to improve our observation capabilities of the large subduction fault in Chile. Three DAS instruments have continuously recorded the ground movement along more than 450 km of underwater optical fiber of the Chilean GTD network for two years.

Activités

• Detect low frequency transient signals in DAS data.
• Identify more specifically the signals indicating transient but slow deformations (slow earthquakes, co- and post-seismic deformations).
1. Use spatial coherence and advanced methods (PCA...) to separate the numerous low-frequency signals, which largely come from thermal variations at the ocean floor related to the circulation of water masses.
2. Apply fine physical models in order to better understand, characterize and correct signals related to oceanic and atmospheric dynamics, and thus isolate those coming from the solid Earth.
• Carry out a preparatory work consisting of identifying in the seismic catalog the "repeaters" that may indicate slow-moving landslides, too weak to be detected from the coast, as well as certain shallow earthquakes associated with near-surface deformations.

Compétences

• Confirmed experience (several years) in geophysical data analysis and visualization, signal processing, and ideally machine learning.
• Working knowledge of Distributed Acoustic Sensing (DAS) and its applications in seismology (appreciated).
• Aptitude for teamwork and scientific collaboration.
• Excellent communication skills, both oral and written, for writing reports and presenting scientific results.
• Flexibility and versatility, essential in the context of an exploratory project faced with unforeseen challenges and opportunities.

Contexte de travail

This recruitment is done within the framework of the ERC ABYSS project funded by Europe. This project aims to transform the observation capabilities of the giant fault of the Chilean subduction, through the use of three DAS instruments that will provide a continuous and dense measure of ground movement over more than 300km, using the fiber optic network under-marines of the Chilean telecom network GTD. The position to be filled is part of the activities of the SEISMES team at the Géoazur laboratory under the supervision of the CNRS, the Observatoire Côte d'Azur, the Université Côte d'Azur and the IRD. The employer of the recruited agent will be the Observatoire de la Côte d'Azur and the workplace will be located on the site of Valbonne Sophia Antipolis (06). The Observatoire de la Côte d'Azur is a national public institution of higher education and research of an administrative nature (EPA) and carries out scientific research missions through its statutes, of observation and knowledge dissemination services of an Observatory of Universe Sciences (OSU).

The Observatoire de la Côte d'Azur gathers and manages the research activities in Earth and Universe sciences of the Riviera region thanks to its mixed service unit, Galilée, and its 3 multi-disciplinary research units (OCA, CNRS, UNS, IRD): Artemis, Géoazur and Lagrange. The Géoazur laboratory is a multidisciplinary joint research unit composed of geophysicists, geologists, and astronomers who federate around major scientific issues: telluric hazards (seismic, gravity-related, and tsunamigenic) and the associated risks, the dynamics of the lithosphere and the imagery of the Earth, the geodesy-metrology of the Earth and the near Universe. It comprises about 170 people (Researchers, teacher-researchers, engineers, PhD students...). It is spread over 2 sites: the CNRS Azur campus in Valbonne Sophia Antipolis and the Calern – Caussols site of the Côte d'Azur Observatory.

The recruited person will join a dynamic group of scientists working on DAS (members of the Earthquake team), who are experts in using DAS data for multiple applications, particularly for seabed seismology. In addition, the ABYSS project will offer very rich interactions with a group of nine people on a wide range of seismological applications of DAS data.