PhD position - Active tectonics - What is tectonic fault damage ?

The PhD work is part of a large proposal, FAULTS_R_GEMS[1] (PI: I. Manighetti, Géoazur), that has been funded by the French Research Agency (ANR) for the period 2018-2021, and that includes 15 national and international (USA, Italy) laboratories. The ANR funding guaranties that the PhD student will have all the necessary means to conduct his/her work in the best conditions. This PhD will be advised by I. Manighetti [2] and F. Leclerc [3], in collaboration with F. Cappa [4] and J-P. Ampuero [5].

As they grow over repeated earthquake ruptures, seismogenic faults damage the embedding rocks in the form of permanent secondary faults and fractures off the master fault. These secondary "damage faults" alter the mechanical properties of the embedding rocks (i.e., increase their compliance), and these changes in turn modify the behavior of the subsequent earthquakes on the master fault. In particular, available observations (see Perrin et al., 2016) suggest that earthquake slip and rupture speed increase on the fault sections surrounded with greater, hence more compliant damage.

The objective of the thesis work is to document tectonic damage off a large number of natural faults worldwide having different lengths, ages, slip modes and hence degrees of structural maturity (see Manighetti et al., 2007), so as to address critical questions such as: which types of deformation are involved in the damage zones, and how are these deformation organized? How large are the damage zones? Are damage extent and compliance related to master fault size, age, slip mode, and maturity? Do damage extent and compliance vary spatially along and across the master fault? Is damage related to lateral fault segmentation?

To address these questions, the PhD student will analyze natural faults of different scales in several sites worldwide where damage zones have been exhumed from crustal depths, exposing the damage fault/fracture traces at the ground surface. The analysis will be mainly based on optical images of different types and resolutions, and field measurements, allowing faults and their damage zones to be studied over a broad range of scales from kilometers to millimeters.

The core of the PhD work is thus active tectonics, but the research strongly relates to fault and rock mechanics and to earthquake physics. It is thus expected that the PhD student has a very strong motivation for research, a solid training in active tectonics, geology, remote sensing, rock mechanics and seismology, motivation and capabilities to work on the field (most sites in Western USA), and facilities to handle quantitative fault measurements. The candidate is also expected to have a good level of English.

More details available upon request.

More information on how to apply here :

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posted: 01 March 2019     Please mention EARTHWORKS when responding to this advertisement.