Project #4

Linking fault damage zone mechanical and geometrical characteristics with fault seismic history

Main Supervisor: Lucilla Benedetti (CEREGE – CNRS)
Co-Supervisor: Giulio Di Toro (UNIPD)

Location: CEREGE – CNRS (France) –

Duration of the PhD: 3 years

The doctoral candidate will be enrolled in a PhD program at the Aix-Marseille Université.

Objectives: The objective of this project is to study the links between coseismic slip distribution, fault segmentation and associated damage zones. Indeed, recent studies suggest that such large variations in slip are possibly due to the presence of barrier zones that stop the rupture. The knowledge accumulated by UNIPD on damage zones distribution and their mechanical properties on one hand, and the experience in mapping active faults and acquiring their seismic history gained by CEREGE over the last 10 years, will allow the PhD student to study those links. In particular, the surface expression of the fault based on the quantification of cumulative displacement (e.g. faceted spurs, fault scarps, geological displacement) along with the accurate mapping of the active portions of the fault will allow him/her to relate slip distribution with fault segmentation, damage and their link with inherited structures. Several sites will be selected on faults displaying different damage zone characteristics and fault cumulative displacement (e.g. the Vado di Corno fault, the Roccapreturo fault) in the Apennines, to quantify geometrical characteristics such as fault length, specific geometrical features in the fault surface expression such as bends, steps of a few km, maximum cumulative displacement, thickness of damage zone, degree of fracturation, specific mechanical properties, using high resolution topography based on digital elevation model acquired from Lidar drone or photogrammetry. Moreover, the fault slip-rate and, if the sites are suitable, its seismic history, will be estimated with 36Cl fault scarp dating and dating of offset markers. Those data will allow the PhD student to unravel how fault maturity, coseismic rupture extent and clustering (coefficient of variation between slip rate and earthquake occurrence) are linked. Seismic ruptures scenarios could be proposed for each target areas on the base of those results and adapted to numerical modelling.

Expected Results:

  1. Relations between fault maturity, coseismic rupture extent and fault slip rate vs. earthquake occurrence;
  2. Relations between fault damage zone distribution and fault rupture segmentation.

Planned secondments: UNIPD (6 months, G. Di Toro, M12-15, Fault zone characterization, field and lab measurements, M29-30, Fault data interpretation, linking with fault maturity); EDF (4 months, K. Manchuel, M19-22, Testing various fault geometry and segmentation of the studied systems into seismic hazard modelling).