Les missions du poste
Closure date for receipt of applications : 19/05/2025
Who are we?
The Marine Hazards team (ALMA) of the Geo-Ocean Laboratory in Plouzané, France observes, characterizes, and models marine geohazards in 4 areas : seismicity and crustal structures, tsunami sources, instabilities and deformation, and fluids and hydrates. The ALMA team spans both Ifremer and Western Brittany University (UBO) and consists of international members. Within ALMA, we have several large-scale research initiatives to address major scientific challenges such as characterizing tectonics and seismic sources from the past to the present, monitoring active volcanism, installing long-term seafloor observatories, characterizing landslides, modeling soil behaviors, and even understanding the pathways of methane gas as IT exits sediments and enters the hydrosphere and atmosphere. With these efforts, we engage communities at both the international and national level.
What is the subject of the thesis ?
The Enriquillo-Plantain Garden Fault Zone (EPGFZ), proposed to BE the southern boundary of the Gonâve microplate in the Caribbean SEA, is a seismically active strike-slip fault branch from the Cayman Trough that is expected to BE passive, such that IT should not generate seismicity. However, earthquake activity along this strike-slip fault since the 1700s indicates that earthquakes can produce vertical uplift along the seemingly transversal fault system and, consequently, tsunamis. To better understand the nature of the EPGFZ, wide-angle seismic data and reflection seismic data were collected during the Haiti-TWiST oceanographic campaign in June and July of 2024 along a 200-km long profile that crossed the center of the Gonâve microplate and the EPGFZ near the Jamaica Passage. During the same SEA campaign, 5 broadband ocean-bottom seismometers were deployed at the 200-km profile's fault crossing to monitor present-day seismicity. The 5 broadband ocean-bottom seismometers were recovered in February 2025, and 4 seismometers were redeployed for an additional year of recording. These active and passive data will BE analyzed to determine the origin and nature of the EPGFZ and image its complex structure. In addition, the identification of the depth of the seismogenic zone is also of interest, as the seismogenic depth is useful for characterizing seismic and tsunami risks. The information gained from this thesis is intended to help complete databases for Caribbean seismic hazard models.
What will your mission BE?
The thesis will address 2 major scientific questions about the EPGFZ using data collected from the Haiti-TWiST oceanographic campaigns :
- How is seismicity linked to the EPGFZ structure and how does the fault release its stress seismically, slow and/or fast? You will use passive broadband seismometer data to 1) detect and locate seismicity (earthquakes and/or tectonic tremor), 2) determine how this segment of the fault releases its stress, and 3) link this seismicity directly to fault structures so that the depth of the seismogenic zone can BE elucidated.
- What is the nature of the crustal blocks surrounding the fault, how is IT related to the history of the Cayman Trough, and what does its nature tell us about the fault's origin? You will use wide-angle seismic and reflection seismic data along a 200-km profile crossing the EPGFZ to unravel the faults tectonic history and determine its crustal nature.
What will your activities BE?
- Detection, location, magnitude estimation, and mechanism determination of earthquakes and/or tremor activity using passive seismological recordings.
- Integration of newly detected seismicity with known earthquake catalogs for interpretation of the seismogenic zone.
- Forward modelling of wide-angle seismic data along a 2-D profile.
- Integrating wide-angle seismic results with reflection seismic data for interpretation of the fault's nature, origin, and structure from shallow to deep.
Key words
Caribbean, plate boundary, geodynamics, deep structures, seismicity
How are your activities organised?
- Research will BE largely conducted at Ifremer's Centre de Bretagne in Plouzané, France.
- A period of 6 months will BE spent at Sorbonne University in Paris to integrate reflection seismic data with wide-angle seismic modelling results.
- Participation in at least 1 international conference (e.g. EGU) is envisioned.
- Depending on fleet scheduling, there could BE an embarkation in 2026 for the final recovery of the passive broadband seismometers.
Le profil recherché
Who are you?
You have the following skills, knowledge and experience :
- Master 2 in geophysics, physics, or geology
- Modelling experience
- Event detection, location, and magnitude determination
- Python programming
You have the following qualities :
- Interested in seismology
- Think critically
- Hard working
- Good time management
- Good communication skills (written and oral), particularly in English
Bienvenue chez Ifremer
Join Ifremer, an ally of planetary well-being, to gain a better understanding of and better protection for the ocean.
From the abyss to the surface, from the coast to the open SEA, Ifremer is the French research institute that is wholly dedicated to the Ocean. Its teams carry out research, innovate and produce expert reports to protect the ocean, exploit its resources in a responsible manner and shares marine data.
Ifremer contributes its scientific expertise to throw light on public policies and develops solutions drawn from the ocean to meet the challenges of the ecological transition. Ifremer is the operator of France's oceanographic fleet with its shipbuilding subsidiary Genavir, and imagines, designs and deploys leading edge technological means to solve the ocean's mysteries.
Join our teams, made up of 1500 scientists and research support staff, present all along the coastal areas of France and French overseas territories.
www.ifremer.fr
Infos complémentaires
What are your benefits?
- The PhD is a real opportunity to work on Ifremer's scientific and technological priority themes. IT entitles the holder to a gross monthly salary of 2300 Euros gross for a period of 3 years, which cannot BE combined with other scholarships.
- We have a teleworking agreement and our staff have 12 comp time days and supra statutory leave.
- We allocate a significant budget to developing skills, through individual or collective training actions.
- We have a CSR policy inspired by the purposes of the institute (sustainable mobility allowance, etc.)
- This PhD grants the rare opportunity to combine active seismic data with passive seismological data in the same study area for analysis and interpretation.
- This PhD offers a collaborative scientific network within and outside of Ifremer as well as outside of France.
- This PhD offers the occasion to improve your English and/or French language skills.
How to apply for this position?
Your application file must include :
- A curriculum vitae
- A cover letter
- A reference letter
- An academic transcript (Bachelor + Master 1 and first semester Master 2)
Your application must BE compiled into 2 PDF files, up to 2 Mo for each file.
The deadline for applications is May 19th, 2025. Nevertheless, we strongly urge you to let us know as soon as possible of your intention to apply, by contacting the subject supervisor : Chastity AIKEN.
In parallel, please submit your application to the Sciences de la Mer et du Littoral (SML) doctoral school of the Western Brittany University (UBO) : https://amethis.doctorat.org/amethis-client/prd/consulter/offre/1030.
Doctoral students' contracts will start as of October 6th, 2025, subject to the submission of administrative documents authorizing Ifremer to recruit the doctoral student (certificate of completion of the Master 2 or engineering degree + visa for foreign doctoral students outside the EU).
What are the next steps?
All applications will BE reviewed following the application closure date. If selected, you will BE contacted for an interview. Depending on the number of applicants or persons interviewed, IT is possible that you may not BE notified about your status, for example if you are not selected for interviews. Interviews will take place from June 2025, and an offer will BE made before the start of the contract (envisioned for October 2025).
