Post-doctoral researcher in Seismology

The institut de physique du globe de Paris

A world-renowned geosciences organisation, the IPGP is associated with the CNRS and an integrated institute of the Université Paris Cité. Bringing together more than 500 people, the IPGP studies the Earth and the planets from the core to the most superficial fluid envelopes, through observation, experimentation and modelling.

The research aeras are structured through 4 main unifying themes: Interiors of the Earth and Planets, Natural Hazards, Earth System and Origins.

The IPGP is in charge of labelled observation services in volcanology, seismology, magnetism, gravimetry and erosion. And the IPGP’s permanent observatories monitor the four active French overseas volcanoes in Guadeloupe, Martinique, Réunion Island and Mayotte.

The IPGP hosts powerful computing resources and state-of-the-art experimental and analytical facilities and benefits from first-class technical support. The IPGP provides its students with geosciences training that combine observation, quantitative analysis and modelling, and that reflects the quality, richness and thematic diversity of the research conducted by the IPGP teams.

Team Department

The Martinique Volcanological and Seismological Observatory is tasked with monitoring, researching and disseminating knowledge in volcanology and seismology, which has led it to continuously exploit data for over 50 years to understand and prevent earthquake risks in Martinique.

The observatory team comprises 12 people: 2 researchers (geophysics), 4 engineers, 3 technicians, 2 secretaries, 2 technical agents.

The two volcanological and seismological observatories in Martinique and Guadeloupe monitor seismic activity in the West Indies subduction zone. For the past 40 years, they have been producing a seismic catalog with the location and

characterization of earthquakes recorded by their seismometer networks, supplemented by the stations of their Caribbean partners. These two catalogs are then merged to form a validated reference catalog.

The IPGP seismology team, made up of 21 permanent researchers, conducts research activities based on the analysis of seismic data and the development and study of analytical and numerical models. The main research themes are Dynamics of tectonic and volcanic systems, Seismogenesis and seismic rupture mechanisms, Seismic ground motion, hazard and risk, Environmental seismology, Instrumentation and instrumental development.

Missions

Following the work initiated in 2019 by the French Ministry of Environment (MTECT) to upgrade the probabilistic seismic hazard assessment in the French West Indies, a new seismo-tectonic zoning has been drawn up. In 2022, IPGP published a first instrumental catalog for the Antilles for the period 2014 to 2019 (Saurel et al., 2022), with updates up to 2022 in preparation. However, to be usable for probabilistic hazard studies, the magnitudes in this instrumental catalog need to be homogenized and converted into moment magnitudes.

The aim of this study is to produce an instrumental catalog of moment magnitudes (Mw) by analyzing the waveforms of seismic events listed in the 2014-2022 catalog. To do this, the researcher recruited will use the SourceSpec code (Satriano, 2023), which, by analyzing S and/or P wave spectra, enables the calculation of seismic source parameters such as seismic moment, corner frequency, radiated energy and stress drop.

Earthquakes with a magnitude greater than around 4.5 can also be analyzed using the ISOLA code (Zahradnik and Sokos, 2018), which calculates the complete moment tensor.

By comparing the seismic moment values obtained by these two approaches, we can mutually validate their results.

Analysis of the resulting catalog will enable us to :

    – Establish a regression relationship between the magnitudes commonly calculated by observatories in the West Indies (Ml, Md) and the moment magnitude Mw.

    – Study the variability of the stress drop as a function of tectonic context: crustal seismicity, subduction interface, deep seismicity.

The results of the work will be presented in a scientific report for MTECT, and will be promoted by one or more scientific articles.

References

Satriano, C. (2022). SourceSpec – Earthquake source parameters from P- or S-wave displacement spectra (v1.7). https://doi.org/10.5281/ZENODO.3688587

Saurel, J.-M., Bouin, M.-P., Satriano, C., Lemarchand, A., OVSG Team, & OVSM Team. (2022). 2014-2019 Antilles IPGP merged seismic catalog. IPGP Research Collection. https://doi.org/10.18715/IPGP.2022.L3YLHAAL

Zahradník, J. & Sokos, E. (2018). ISOLA code for multiple-point source modeling –review. in Moment Tensor Solutions – A Useful Tool for Seismotectonics 1–28 (Springer Natural Hazards, 2018). https://doi.org/10.1007/978-3-319-77359-9

Activities

Research activities will take place at the Observatoire volcanologique et sismologique de Martinique (OVSM), after a two-week initial period at the Institut de physique du globe in Paris. Main contacts will be Claudio Satriano (assistant physicist at IPGP), Jordane Corbeau (assistant physicist at OVSM) and Jean-Marie Saurel (research engineer at IPGP).

In addition to research activities, the person recruited will also be involved in day-to-day OVSM tasks, such as daily seismicity monitoring, on-call duty and field missions.

Expected Skills

• A solid knowledge of seismology of the seismic source is essential.
• Programming skills, preferably in Python, are desirable.
• A positive aptitude for teamwork and writing scientific reports and articles is required.

Obligations and risks

• The observatory is open Monday to Friday, 8:30am to 6pm.
• The person recruited will be assigned to the Martinique Volcanological and Seismological Observatory, where the work is varied and multidisciplinary, both in the laboratory and in the natural environment.
• This position requires interpersonal skills adapted to working in a small team, often confronted with crisis situations (earthquake felt, volcanic activity), and in relation with the authorities and the media under the supervision of the observatory manager.
• Participation in the life of the observatory will be desirable: routines, voluntary scientific and technical monitoring shared between several team members.
• Travel is expected, particularly to the IPGP seismology team in Paris, Guadeloupe and the Caribbean region.

Training and experience required

0 to 3 years of experience

Diploma : phD

How to apply

Send CV and cover letter to , and

Deadlines for applications : 2023 October 1st