PhD Projects

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

Location: Université Grenoble-Alpes (France) – www.univ-grenoble-alpes.fr

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).

Main Supervisor: Men-Andrin Meier (ETH Zurich)
Co-Supervisor: David Marsan (UGA)

Location: Swiss Federal Institute of Technology (Switzerland) – ethz.ch

Duration of the PhD: 3 years

The doctoral candidate will be enrolled in a PhD program at the Swiss Federal Institute of Technology

Objectives: Aseismic processes can play a first-order role in the build-up to large earthquakes, but they are hard to detect and monitor. The strong recent advances in seismic monitoring with deep learning (DL) techniques is an opportunity to improve the detection and characterisation of the subtle seismic signatures that aseismic processes leave behind. The doctoral candidate will i) develop new DL methods that are tailored to characterise the seismic signatures of aseismic slip during earthquake sequences. This may include stress migration and rotation, strain acceleration as captured by repeating earthquakes, and fluid pressure build-up as evidenced by seismic swarms; and ii) study the predictive value of aseismic observations for anticipating large earthquakes. We will use some of the recent, exceptionally well recorded earthquake sequences (natural or stimulated) to constrain transient aseismic deformation, including deformation caused by underground fluid flow. From this observational basis we will develop mixture seismicity models that account for the observed triggering of earthquakes by aseismic transients and previous shocks. This will allow us to study how the total deformation is partitioned into seismic and aseismic contributions, in space and in time. The goal is to understand the physics of the hard-to-observe aseismic deformation, and to design a seismicity model that provides substantially improved probability gain, compared to state-of-the-art models.

Expected Results:

1. Development and implementation of DL monitoring method to generate next-level, deep seismicity catalogues;
2. Monitoring and inference of aseismic deformation, and their underlying driving mechanisms such as fluid flow;
3. Operational seismicity model for predicting the evolution of earthquake sequences;
4. Improved understanding of the interactions between seismic and aseismic deformation mechanisms;
5. Data-driven, objective inference of fault structures and geometries at small, decametre scale.

Planned secondments: UGA (12 months, D. Marsan, M19-30, Developing the mixture seismicity model, and its physical interpretation in terms of seismic and aseismic deformation processes).

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

Location: CEREGE – CNRS (France) – www.cerege.fr

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).

Main Supervisor: André Niemeijer (UU), Giulio Di Toro (UNIPD)
Co-Supervisor: Hans de Bresser (UU), Telemaco Tesei (UNIPD)

Location:Universiteit Utrecht (Netherlands) – www.uu.nl

Duration of the PhD: 3 years

The doctoral candidate will be enrolled in a PhD program at the Universiteit Utrecht

Objectives: The rheology of carbonates during the seismic cycle, especially in the presence of pressurized fluids and at the viscous-plastic to elasto-frictional transition, remains poorly understood. In the project, we will perform experiments on both intact carbonate rocks as well as fault gouges under conditions where the transition from crystal-plastic flow to frictional behaviour might be activated.  Detailed microstructural analyses down to the nanoscale (UU & UNIPD) of the experimental products and comparison with natural fault rocks from the deep roots of fault zones exposed in the Apuane Alps (Italy) and Western Alps (Switzerland) (UNIPD) will allow us to 1) test whether the deformation mechanisms activated in the experiments occur in natural faults, 2) test and update existing calcite paleo-piezometers to estimate the state of stress at earthquake nucleation depths and beyond, 3) define the conditions under which the transition from volume-conservative crystal-plastic deformation to volume-dependent frictional deformation occurs (i.e., viscous-plastic to elasto-frictional transition). Additionally, existing flow laws for creep in fine-grained calcite aggregates that have been used to predict shear strength during seismic sliding will be tested and updated, also for their utilization in other fellow projects on the modelling of the seismic cycle proposed in TREAD.

Expected Results:

1. Identification of the dominant deformation mechanisms across the transition from friction to flow behaviour in experimental and natural carbonate fault rocks;
2. Updated and tested microphysical models (laws) for the full range of velocities encountered in the seismic cycle;
3. Critical assessment of existing paleopiezometers for wet calcite rocks.

Planned secondments: UNIPD (12 months, G. Di Toro, M13-18 & M25-30, Collection of natural fault rocks and experiments at low effective normal stress).

Main Supervisor: Giulio Di Toro (UNIPD), Alice Gabriel (LMU)
Co-Supervisor: Faccenda (UNIPD)

Location: Università degli Studi di Padova (Italy) – www.unipd.it

Duration of the PhD: 3 years

The doctoral candidate will be enrolled in a PhD program at the Università degli Studi di Padova

Objectives: The doctoral candidate will exploit the rich dataset already available at UNIPD of field studies regarding the spatial distribution of fault damage zones in active faults of the Italian Central Apennines and perform other few selected studies. By means of dynamic rupture earthquake as well as seismic sequence modelling simulations, the mechanism of formation and spatial distribution of fault damage zones will be discussed with respect to (1) the maximum magnitude of the earthquake associated to the studied fault, (2) fault geometry (length, presence of step overs, etc.), (3) lithology of the wall rocks. The earthquake modelling simulations will exploit powerful computational facilities and numerical models (e.g., the discontinuous Galerkin method) which will integrate frictional constitutive laws obtained from the laboratory with realistic fault zone geometries. This approach will result in the identification of the physical, geological and loading conditions which control the propagation of seismic ruptures and the formation and distribution of fault damage zones. Computational facilities are available at UNIPD and LMU both for development, benchmarking and testing of the methodology. This PhD position will provide a young researcher with a quite unique background spanning from field geology to sophisticated numerical modelling. Additional research stays at the Scripps Institution of Oceanography, UC San Diego, are possible.

Expected Results:

1. Mechanism of formation of fault damage zones;
2. How the presence of damage zones affects individual seismic ruptures and the evolution of seismic sequences;
3. How the presence of damage zones affects the near field seismic wave radiation and associated strong ground motions.

Planned secondments: LMU (12 months, Alice Gabriel, M13-18 M25-30, physically-based 3D fully dynamic simulations of individual earthquakes and of the seismic cycle with the discontinuous Galerkin method (this code allow treating complex 3D geological structures, nonlinear rheologies (including off-fault plastic yielding) and high-order accurate propagation of seismic waves: https://github.com/SeisSol/SeisSol and https://tear-erc.github.io/tandem-egu21/).

Main Supervisor: Ylona van Dinther (UU)
Co-Supervisor: Taras Gerya (ETH), Alice Gabriel (LMU)

Location: Universiteit Utrecht (Netherlands) – www.uu.nl

Duration of the PhD: 4 years

The doctoral candidate will be enrolled in a PhD program at the Universiteit Utrecht

Objectives: Recent 2D tectonic earthquake sequence modelling of the Northern Apennines reveals that realistic tectonic loading and deep structures and rheology have a major impact on earthquake sequences in the upper continental crust. Specifically, the stress field and the type, distribution and rate of earthquakes in Northern Apennines are significantly affected by slab pull and lower crustal rheology, although these are not taken into account in earthquake sequence modelling or seismic hazard assessment. To understand these key features this doctoral candidate will first extend 2D visco-elasto-plastic, seismo-thermo-mechanical models, simulating earthquake sequences following millions of years tectonic, topography and fault evolution, down to milliseconds of earthquakes from strike slip to complex continental settings. To computationally efficiently simulate wave-mediated stress transfer in 3D, faults stress states will be coupled to the dynamic rupture model following recent achievements. Second, these new state-of-the-art models will be applied to spontaneously simulate and understand seismic hazard parameters (i.e., Mmax and b-value) as a function of important tectonic and rheological parameters (e.g., loading by mantle and lower crust, carbonate rheology, fluid flow). Third, a scenario in the Betics (Spain) will be constrained by observations from field studies, geodesy, seismology and fault geometries, and microphysical friction laws, using instantaneous modelling to assess its seismic hazard and compare those outcomes to more traditional PSHA approaches to converge towards a more physics-inspired PSHA methods.

Expected Results:

1. 2D cross-scale / 3D coupled visco-elasto-plastic tectonic earthquake sequence models for complex continental settings;
2. Improved understanding of how key tectonic and rheological parameters affect seismic hazard parameters in complex continental settings;
3. Data-constrained physics-based scenario for seismic hazard assessment in the Betics.

Planned secondments: LMU (9 months, A. Gabriel, M18-22 & M34-37, Couple tectonic earthquake sequence models to dynamic rupture models in 3D complex continental settings for ground motion and hazard assessment); TNO (3 months, J.-D. van Wees, Loes Buijze, M27-29, model Mmax for induced seismicity in geothermal reservoirs using Linear Elastic Fracture Mechanics).

Main Supervisor: Alice-Agnes Gabriel (LMU)
Co-Supervisor: Sebastien Hok and Oona Scotti (IRSN), Yann Klinger (IPGP)

Location:Ludwig-Maximilians-Universität München (Germany) – www.lmu.de

Duration of the PhD: 3 years

The doctoral candidate will be enrolled in a PhD program at the Ludwig-Maximilians-Universität München

Objectives: Recent, well recorded earthquakes reveal complex fault-ruptures involving many different fault sections. Evaluating the possibility of future complex ruptures in any given fault system remains to this day a major challenge for seismic and surface fault displacement hazard assessments. This project will develop 3D dynamic earthquake rupture scenarios across complex fault systems combining nonlinear frictional failure and seismic wave propagation. Empowered by supercomputing, such models will produce physics-based forecasts of ground motions and surface fault displacement as well as fault interaction, thus providing insight into fundamental processes of earthquake physics. The rich amount of data available in the Central Apennines, Italy, will be used among others to first validate dynamic rupture simulations for chosen recent events integrating data from field work, geodesy, seismology and laboratory data. A special focus will be the characteristics of surface rupture that can shed light on shallow fault rupture processes during earthquakes, which in turn open the way to a better assessment of earthquake surface rupture hazards. This work will use an approach similar to that developed for the modelling of the 2016 Mw7.8 Kaikôura earthquake, New Zealand and the 2016 Norcia, Italy earthquake. In a second step, the doctoral candidate will extract all mechanically viable earthquake rupture scenarios, compute physics-based ground motion models accounting for source/site and path effects, and use this information to construct a range of plausible fault models for hazard assessment using tools such as SHERIFS to explore epistemic uncertainties and OpenQuake Engine to compute seismic hazard at selected sites. Additional research stays at the Scripps Institution of Oceanography, UC San Diego, are possible.

Expected Results:

1. Physically constrained ground motions and surface ruptures including the exploration of non-linear source-path-site effects in complex dynamic earthquake ruptures;
2. Physically viable multi fault rupture scenarios constrained by and validated against available data;
3. Integration of physics-based complex fault rupture scenarios in fault-based seismic and surface fault displacement hazard assessments.

Planned secondments: IPGP (3 months, Y. Klinger, M12-14, Inference of 3D fault geometry from field and geodetic data), IRSN (4 months, S. Hok & O. Scotti, M24-27, Assimilation and validation of 3D models with observations), GEM (1 month, M. Pagani, M30, Integration in operational hazard assessment), Munich-Re (1 month, M. Kaser, M38, Implications for risk models with GeoRisk section).

Main Supervisor: Bruno Pace (Ud’A)
Co-Supervisor: Alessandro Verdecchia (RUB), Laura Peruzza (OGS), Francesco Visini (INGV)

Location:Università degli Studi di Chieti-Pescara (Italy) – www.unich.it

Duration of the PhD: 3 years

The doctoral candidate will be enrolled in a PhD program at the Università degli Studi di Chieti-Pescara

Objectives: The doctoral candidate project will investigate the recurrence times, their variability and probability of occurrences of moderate-to-large magnitude earthquakes in a fault-based 3D model, including coseismic Coulomb stress changes, and time-dependent fluid migration and viscoelasticity. The 3D fault model will mimic complex networks of active faults (e.g. central Apennines or lower Rhine graben). The objective is to build a workflow, computational resources and realistic benchmarks that can be tuned to include alternative inputs. These will simulate synthetic catalogues of earthquake ruptures, including multi-fault ruptures, useful to study how inputs affect the resulting space-time evolution of earthquake series and their epistemic uncertainties. The available earthquake catalogues (instrumental, historical and paleoseismological catalogues) will be used to rank the modelled space-time earthquake series.

Expected Results:

1. Synthetic catalogues of earthquake ruptures;
2. Sensitivity analysis on input variability and uncertainties.

Planned secondments: RUHR (6 months, A. Verdecchia, M13-18, modelling coseismic Coulomb stress changes, fluid migration and viscoelasticity); OGS (4 months, L. Peruzza, M35-38, sensitivity analysis on input variability and uncertainties).

Main Supervisor: Marco Pagani (GEM)
Co-Supervisor: C. Beauval, A. Soquet, D. Marsan (UGA), F. Agliardi (UNIMIB)

Location:Fondazione GEM, Pavia (Italy) – www.globalquakemodel.org

Duration of the PhD: 3 years

The doctoral candidate will be enrolled in a PhD program at the Università degli studi di Milano Bicocca, Italy

Objectives: In this PhD we aim to address two aspects related to the modelling of distributed seismicity sources. We will test methods that define earthquake occurrence by considering deformation transients (e.g., changes in long-term background rates/coupling or fluid intrusions and related swarms). For example, we will test the definition of time-varying seismicity rates inverted from geodetic data and examine the definition of a strain-dependent corner-magnitude in a tapered Gutenberg-Richter distribution. We will test the methodologies proposed using seismicity models based on ETAS or MISD. In a second part, we will address the problem of combing distributed and fault sources within active areas. Firstly, the doctoral candidate will study the scaling of seismicity occurring in the proximity of faults. In the following phase, they will test various criteria for combing faults and distributed seismicity models and analyze the impact that different approaches have on the spatial pattern of earthquake occurrence and seismic hazard. Overall, the expected results will have an impact on the way in which we model seismic hazard in various tectonic regions and will help to improve the hazard and risk forecasts based on probabilistic methods.

Expected Results:

1. New approaches to define distributed seismicity sources, relying on geological and geodetic information;
2. New methods for combining distributed seismicity and fault sources.

Planned secondments: UGA (9 months, C. Beauval, A. Soquet, D. Marsan, M12-18 and M23-29, Developing distributed seismicity models by considering deformation transients); IRSN (3 months, O. Scotti, M30-33, Testing the methods in a real case study).

Main Supervisor: Vitor Silva (GEM)
Co-Supervisor: Bruno Pace (Ud’A)

Location:Fondazione GEM, Pavia (Italy) – www.globalquakemodel.org

Duration of the PhD: 3 years

The doctoral candidate will be enrolled in a PhD program at the Università degli Studi di Chieti-Pescara

Objectives: Aseismic processes can play a first-order role in the build-up to large earthquakes, but they are hard to detect and monitor. The strong recent advances in seismic monitoring with deep learning (DL) techniques is an opportunity to improve the detection and characterisation of the subtle seismic signatures that aseismic processes leave behind. The doctoral candidate will i) develop new DL methods that are tailored to characterise the seismic signatures of aseismic slip during earthquake sequences. This may include stress migration and rotation, strain acceleration as captured by repeating earthquakes, and fluid pressure build-up as evidenced by seismic swarms; and ii) study the predictive value of aseismic observations for anticipating large earthquakes. We will use some of the recent, exceptionally well recorded earthquake sequences (natural or stimulated) to constrain transient aseismic deformation, including deformation caused by underground fluid flow. From this observational basis we will develop mixture seismicity models that account for the observed triggering of earthquakes by aseismic transients and previous shocks. This will allow us to study how the total deformation is partitioned into seismic and aseismic contributions, in space and in time. The goal is to understand the physics of the hard-to-observe aseismic deformation, and to design a seismicity model that provides substantially improved probability gain, compared to state-of-the-art models.

Expected Results:

1. A suite of case studies and openly accessible tools for assessing the impact of different hazard modelling techniques on the earthquake risk. These tools will be incorporated into the existing OpenQuake framework;
2. A set of recommendations to perform earthquake scenarios and probabilistic seismic risk analyses using advanced hazard modelling approaches.

Planned secondments: Ud’A (4 months, B. Pace, M24-27, Exploring time-dependent and fault-based seismic hazard models in seismic risk assessment). Willis Limited (4 months, C. Petrone, M36-39, Assessing the impact of different hazard modelling techniques in probabilistic risk metrics).