Project #2

Combining InSAR and seismo-thermo-mechanical models to understand earthquake sequences in complex fault system: application to Central Apennines (Italy)

Main Supervisor: Erwan Pathier (UGA)
Co-Supervisor: Ylona Van Dinther (UU), Anne Socquet (UGA)

Location: Université Grenoble-Alpes (France) –

Duration of the PhD: 3 years

The doctoral candidate will be enrolled in a PhD program at the Université Grenoble-Alpes.

Objectives: Earthquake sequences within complex fault systems are difficult to study because geodetic and seismological observations are too short in time to accurately sample different phases of the earthquake cycle. Developments in InSAR technology provide unprecedented spatially dense geodetic measurements complementing the GNSS permanent network. Recent results in the Central Apennines raise first-order questions about the tectonic mechanisms explaining the uplift and horizontal strain distribution in the Apennines. It also offers new opportunities to incorporate geodetic data into seismic hazard assessment in such complex and distributed fault systems. However, when using InSAR data for hazard purposes we face several challenges, including (1) separating the strain accumulation signal from other sources of deformation, (2) limited knowledge of the fault geometry and rheology, and (3) uncertainty about the stationarity of the interseismic signal over several cycles. This project addresses these challenges using seismo-thermo-mechanical (STM) numerical models with realistic rheology and loading, which simulate both earthquake sequences and long-term deformation (Myr). STM models will be used to test and form hypotheses about fault geometry, rheology and strain accumulation in close connection to geodetic observations (inter-, co- and post-seismic signals), seismological catalogues and long-term topography and geological constraints. Synthetic interseismic surface displacement and earthquake sequence catalogues will be used to assess accuracy of geodetic inversion for slip rate assessment on individual faults and to evaluate the temporal variability of surface displacements and earthquake catalogues. These are important steps to improve slip rate and hazard estimates in the Central Apennines and after this project to many other places in the world.

Expected Results:

  1. Surface displacements in the Apennines combining InSAR and GNSS isolating the interseismic deformation signal;
  2. Improved geodetic inversion procedures for complex fault system settings;
  3. 2D and 3D earthquake sequence simulations using a visco-elasto-plastic rheology, realistic tectonic loading and fault systems for the Central Apennines;
  4. Statistical analysis of the simulation and comparison with geodetic observations and seismic catalogues.

Planned secondments: UU (9 months, Y. van Dinther, M18-21, M34-38, 2D and 3D STM models in the Central Apennines focusing on (1) the interseismic period and (2) earthquake sequence statistics); TRE-Altamira, (3 months, M. Bianchi, M12-14, Compilation of InSAR time series over Apennines and using InSAR for induced seismicity target).