Missions

While seafloor spreading appears like a continuous process on geological time scales, on human time scales it manifests as discrete events of tectonic (fault slip) or/and magmatic (diking) extension. The goal of this 2.5-year postdoctoral position is to investigate the mechanical interaction between dike intrusion and normal fault slip events, by means of quasi-dynamic boundary element modeling.

The postdoctoral researcher will implement dike intrusion events in a rate-and-state friction-based seismic cycle simulator. As an initial step, the timing and evolution of each dike intrusion will be prescribed, and the effect of diking on an adjacent normal fault will be systematically investigated. The postdoctoral researcher will then work to implement magmatic intrusions that initiate and grow in accordance with the dynamically-evolving ambient stress field.
Simulation results will be compared to seismological and geodetic data compiled across the global mid-ocean ridge system. The end-goal of this project is to design a novel modeling framework where dikes and normal faults can trigger and/or inhibit each other, providing insight into how tectonic and magmatic strain self-consistently partition on decadal time scales during seafloor spreading.

Activités

- Designing parsimonious models of dike intrusions, including: triggering criterion, simplified propagation dynamics (accounting for viscous magma flow), and arrest criterion.
- Implementation of diking in the quasi-dynamic seismic cycle simulator FASTDASH (Python/C++), which relies on a boundary element approach accelerated by the hierarchical matrix method.
- Running a large number of simulations to investigate a wide parameter space of dike / fault geometries and rheological properties
- Interpreting simulation results in light of observations from the global mid-ocean ridge system
- Writing and documenting code for open distribution
- Communicating the results at international conferences and publishing them in international, open-access journals

Compétences

- Background in computational seismology, geodynamics, tectonics, geophysics, solid mechanics
- Knowledge of solid mechanics including basic elasticity theory and elastodynamics, fluid mechanics
- Experience with numerical modeling of seismic cycles, such as (quasi-)dynamic rate-and-state fault rupture models
- Programming in C / python / Julia or equivalent, and ideally some experience with high-performance computing
- Familiarity with the following topics is a plus: boundary element techniques and underlying mathematical theory, including acceleration methods (e.g., Hierarchical matrices), physical volcanology, rifting and seafloor spreading
- Strong scientific writing and oral communication skills, and proficiency in English are required. French is optional

Contexte de travail

The postdoctoral researcher will be employed by CNRS (Délégation Paris Centre), and carry out their research within Ecole Normale Supérieure's Geology Laboratory, a joint research unit bringing together CNRS researchers and ENS-PSL faculty members. The successful candidate will join the Deformation and Structures team, which specializes in the observation and modeling of tectonic processes, from grain to lithospheric scale, and from seismic cycles to the growth of major geological structures. The research will be conducted under the supervision of Jean-Arthur Olive, in collaboration with Harsha Bhat. This research is part of ERC project SeaSALT (Seafloor Spreading on Short And Long time scales, PI: J.-A. Olive), which will involve a team of PhD students and post-docs working on different aspects of seafloor spreading (magmatism, tectonics, hydrothermalism) on a range of time scales, with observational and modeling approaches. The postdoctoral researcher will also benefit from a network of national and international collaborations to support the development of numerical models, and their comparison with observations of active deformation at mid-ocean ridges.