Research interests in a nutshell:

I am a postdoc in Jeroen Tromp's group and interested in full-wave seismology, forward and inverse modeling, and seismic tomography at local to global scales.

Any progress on seismic hazard assessment, earthquake rupture processes, nuclear test ban monitoring, tsunami modeling, predicting volcano eruptions, carbon sequestration, oil exploration, Earth's energy budget, past plate motions, and geomagnetism necessitates reasonable models of ambient medium properties in space and time. Seismic waves emanating from earthquakes or active explosions lend themselves very well to illuminating the earth's interior due to their weak attenuation over large distances and modern instruments capable of detecting small ground motions at a large range of frequencies. My work is underpinned by numerical methods for realistic simulations of seismic-wave propagation which is paramount to any imaging procedure, and thus, together with appropriate inversion techniques, the crux of obtaining realistic models of the subsurface.

Global wave propagation and tomography
Distinguishing the base of the thermally convecting mantle from the chemically convecting fluid core that generates the magnetic field, the core-mantle boundary region represents one of the structurally and dynamically most fascinating regions of the Earth. Unfortunately, tomographic models suffer from their limited deep-mantle resolution, and waveform modeling or array studies cannot deliver a contiguous global map. I have developed a dedicated spectral-element method to propagate seismic waves through spherically symmetric Earth models. Exploiting symmetries in the radiation patterns for moment-tensor earthquake sources, the resultant 2-D computational domain allows for efficient storage of entire wavefields at the scale of the Earth. These spatio-temporal fields constitute the basis of "exact", arbitrary-resolution (e.g., 1 Hz signals) 3-D Fréchet sensitivity kernels for any fraction of a broadband seismogram. Large-scale tomographic inversions based on e.g. core-diffracted waves, the incorporation of discontinuity undulations, the extent to which the Born approximation is valid and other global-scale topics related to sensitivity of seismic waves are a natural application of this idea and work-in-progress.

This work is done in collaboration with Tony Dahlen, Alexandre Fournier, Guust Nolet, and Karin Sigloch. The spectral-element method will be released on an open-source basis after some more cross-platform, high-resolution benchmarking and thorough code commenting.

Wave propagation and adjoint methods in complex crustal structures
At local scales, 1D models are insufficient as an approximation to the real Earth such that the above collapsed-dimension strategy is not applicable. These shallow depths are not only the most accessible and well-resolved, but also the most complex and important for societal issues ranging from anthropogenic warming mitigation to natural hazards and resources. The major challenge lies not within using more previously unappreciated data such as in the global case, but accounting for complexities in the model space. The new spectral-element solver (SESAME, geodynamics.org) I am co-developing will simulate anisotropic, visco- and poro-elastic waves through such geometries. Typical exploration-industry practices take crude approximations to the forward (e.g. 2D acoustic media) and inverse problem (ray theory, no multiple reflections). We discretized 2D models including strong surface topography, overthrusting faults, salt bodies, wedges, thin layers and lenses. To obtain images, our full-wave strategy culminates in an adjoint method as popularized in the atmospheric sciences. This opens the door to joint interface inversions and volumetric wavespeed tomography, a fundamental trade-off that is central to global and exploration seismology. Our results show compelling evidence for significantly crisper images of these complex structures. This work is in collaboration with Jeroen Tromp, Yang Luo, Hejun Zhu, and Christina Morency (Princeton), Andreas Plesch and John Shaw (Harvard).

Other research topics
Other topics of interest include spectral-element dispersion analysis, high-order time extrapolation schemes (e.g., symplectic), 3-D elastic wave propagation through subduction zones, and helioseismology. Ultimately, I am always partial to careful interpretation of seismic images in terms of structural, mineralogical and geodynamic implications.

If you are interested in collaborating, contributing, or potential Ph.D./M.Sc./postdoc projects at ETH Zurich, please contact me.