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2 PhD Positions in Seismology (starting spring 2021)

29. Sep 2020

The SPIN project (more information and www links to follow) is a 4-year EU Training Network that starts March 1, 2021. Beneficiary Partner Institutions are University of Hamburg (coordinator), GFZ Potsdam, IPG Paris, ETH Zurich, ISTERRE Grenoble, University of Edinburgh and British Geological Survey, and the Dublin Institute of Advanced Studies. The project also involves industrial partners. Secondments to other universities and industry are obligatory.

Scope : If you would look at a seismic wavefield in detail, you would notice that it carries the imprint of materials that it has crossed. We now understand that seismic wavefields alter the material when they pass through it and that these changes are measurable. This is important, because dynamic material behaviour affects our societies: geomaterial alterations are associated with many natural hazards, such as volcanic eruptions, landslides, earthquakes, and the changing health status of civil structures such as bridges and buildings. Traditional seismic sensors - seismometer networks - provide us with high time resolution, but sparse spatial resolution. Right now, new sensing technologies (DAS, large N arrays, rotation sensors) are emerging that can give us much more detailed spatial information about how the seismic wavefield behaves. This means that we can study changes in local material properties, and investigate complex behavior of materials as they deform under small strain. These sensing technologies are reaching a level of maturity where they can be incorporated into common seismological observation practice, and it opens a new era of observations for which new skills need to be developed. In SPIN, we will train a new generation of scientists to develop novel views about the dynamic behaviour of Earth materials, and in particular how to observe them with the revolutionary new sensing systems at hand. It is currently enigmatic how to combine these sensor types to optimize resolution power. This research and training will impact the way we understand solid Earth processes, how we interrogate the Earth’s geomechanical behavior, and the way we forecast natural hazards.

PhD Project 1:

High quality 6 Degrees of Freedom point measurement - towards absolute amplitude measurements

Supervisors: H. Igel, A. Gabriel External supervisor: C. Schmelzbach (ETH) Intersectoral supervisor: F. Guattari (iXBlue)

Objectives: The wave propagation physics we study requires the highest possible quality of seismic ground motion observations. Several partners of SPIN (LMU, ETH, UHH, iXblue) have pioneered the concepts of 6 DoF ground motion observations in combination with emerging technologies to measure rotational ground motions. This project aims at developing (automated) data analysis tools for ingle station and networks of 6 DoF ground motion observations to increase the resolving power of seismic inverse problems for both structure and source. This shall involve both probabilistic approaches as well as deep learning strategies that will be trained with synthetic data. In addition, the highly successful noise-based cross-correlation methodology shall be extended to the new rotation observations, with the aim to further constrain time-dependent structural and nonlinear effects. The methodology shall be applied to field data at 1) active seismic faults, 2) volcanoes, 3) ocean-bottom observations, 4) teleseismic observations using ring lasers, and 5) laboratory data (tilt correction). This project is tightly linked to other SPIN work packages developing wave simulation techniques and through the non-academic partner (iXBlue) who develops rotation sensors.

Expected results:
- Open source synthetic 6 DoF benchmark data for processing, data analysis, and inverse problems
- Processing toolbox (Full 6 DoF ) with documentation, embedded in Jupyter notebooks
- Case studies on field and laboratory data, demonstrate improvement in inverse problem resolution

Planned secondments: Host, supervisor, timing, length and purpose
- iXblue - F. Guattari - 1M/yr - Adaptation of data processing to hardware developments
- CNRS-LSBB - S. Gaffet, O. Sebe - 1M in Y1 - test deployment 6DOF measurement
- ETH - C. Schmelzbach - 2M in Y2 - Integration of wavefield separation and polarization analysis into processing toolbox

PhD Project 2 :

Numerical models across the scales

Supervisors: A. Gabriel, H. Igel External supervisor: Y. Capdeville (CNRS-Nantes)
Intersectoral supervisor: F. Guattari (iXBlue)

Objectives: The observations indicative of nonlinear wave propagation as well as experimental concepts involving all motion components recorded by new sensors types (displacement, strain, and rotation) are currently not fully supported by classic 3C modelling schemes. We build on our decades-long experience in developing forward and inverse solutions in computational seismology to adapt computer programs serving the scientific tasks of all work packages in SPIN. In particular we 1) include nonlinear models for wave propagation, 2) provide test data sets to explore sensitivities of various nonlinear rheologies, 3) provide wave simulation scenarios across the scales from laboratory (rock), to local (crust), to global scales (incl. mantle), and 4) use scenario calculations to optimize the experimental design. This project transfers simulation technology to all other work packages and builds on the EU project ExaHyPE, that has developed a new scalable solver for large-scale supercomputers, and it links to ongoing collaboration on waves in strongly heterogeneous media (homogenization, CNRS-Nantes).

Expected results:
- Improved physical model for material response to stress and dynamic strain, resulting wave propagation
- Benchmark synthetic data set for multi-component large-N experiment at LSBB
- Multi-scale open source solver for nonlinear seismic wave propagation problems

Planned secondments: Host, supervisor, timing, length and purpose
- CNRS-Nantes - Y. Capdeville - 1M/yr - adapting and testing waves in heterogeneous media, homogenization
- DIAS - C. Bean - 1M/yr - application of solver to specific hazard-related forward and inverse problems
- BAM -E. Niederleithinger - 1M in Y2 - application to damage estimation models on civil engineering scale

How to apply?
Applications are accepted until the positions are filled. Please send a complete application with CV, a statement of research interests in response to the scope of the project (one page), names of two references, preferably in PDF format to: Prof. Dr. Heiner Igel (e-mail: heiner.igel@lmu.de).

by Heiner Igel last modified 30. Sep 2020 12:08
Printed 22. Oct 2020 23:35