A5017764759- Seismic Imaging and Inversion Techniques
- Seismic Waves and Analysis
- Seismology and Earthquake Studies
- earthquake and tectonic studies
- High-pressure geophysics and materials
- Geophysics and Sensor Technology
- Geological and Geochemical Analysis
- Reservoir Engineering and Simulation Methods
- Geophysical Methods and Applications
- Landslides and related hazards
- Cryospheric studies and observations
- Hydraulic Fracturing and Reservoir Analysis
- Underwater Acoustics Research
- Medical Imaging Techniques and Applications
- Advanced Fiber Optic Sensors
- Ultrasonics and Acoustic Wave Propagation
- Earthquake Detection and Analysis
- Methane Hydrates and Related Phenomena
- Geological Modeling and Analysis
- Drilling and Well Engineering
- Geophysics and Gravity Measurements
- Hydrocarbon exploration and reservoir analysis
- Speech and Audio Processing
- Structural Health Monitoring Techniques
- Geophysical and Geoelectrical Methods
ETH Zurich
2016-2025
Czech Academy of Sciences, Institute of Geophysics
2018-2025
University of Texas Institute for Geophysics
2020-2025
Board of the Swiss Federal Institutes of Technology
2019-2024
Institute of Seismology
2022
University at Buffalo, State University of New York
2021
Utrecht University
2009-2018
École Polytechnique Fédérale de Lausanne
2013-2018
Charles River Laboratories (Netherlands)
2018
John Wiley & Sons (United States)
2018
To evaluate the efficacy and safety of certolizumab pegol (CZP) after 24 weeks in RAPID-axSpA (NCT01087762), an ongoing Phase 3 trial patients with axial spondyloarthritis (axSpA), including ankylosing spondylitis (AS) non-radiographic axSpA (nr-axSpA).Patients active were randomised 1:1:1 to placebo, CZP 200 mg every 2 (Q2W) or 400 4 (Q4W). In total 325 randomised. Primary endpoint was ASAS20 (Assessment SpondyloArthritis international Society 20) response at week 12. Secondary outcomes...
We present a full seismic waveform tomography for upper-mantle structure in the Australasian region. Our method is based on spectral-element simulations of wave propagation 3-D heterogeneous earth models. The accurate solution forward problem ensures that misfits are solely due to as yet undiscovered Earth and imprecise source descriptions, thus leading more realistic tomographic images parameter estimates. To reduce computational costs, we implement long-wavelength equivalent crustal model....
We present a high-resolution S-velocity model of the North Atlantic region, revealing structural features in unprecedented detail down to depth 1300 km. The is derived using full-waveform tomography. More specifically, we minimise instantaneous phase misfit between synthetic and observed body- as well surface-waveforms iteratively full three-dimensional, adjoint inversion. Highlights upper mantle include well-resolved Mid-Atlantic Ridge two distinguishable strong low-velocity regions beneath...
We develop and apply a full waveform inversion method that incorporates seismic data on wide range of spatio-temporal scales, thereby constraining the details both crustal upper-mantle structure. This is intended to further our understanding crust–mantle interactions shape nature plate tectonics, be step towards improved tomographic models strongly scale-dependent earth properties, such as attenuation anisotropy. The for detailed regional structure consistently embedded within large-scale...
Abstract Records of Alpine microseismicity are a powerful tool to study landscape-shaping processes and warn against hazardous mass movements. Unfortunately, seismic sensor coverage in regions is typically insufficient. Here we show that distributed acoustic sensing (DAS) bridges critical observational gaps seismogenic terrain. Dynamic strain measurements 1 km long fiber optic cable on glacier surface produce high-quality seismograms related flow nearby rock falls. The nearly 500 channels...
In this paper, we present a series of mathematical abstractions for seismologically relevant wave equations discretized using finite-element methods, and demonstrate how these can be implemented efficiently in computer code. Our motivation is to mitigate the combinatorial complexity when considering geophysical waveform modelling inversion, where variety spatial discretizations, material models, boundary conditions must considered simultaneously. We accomplish goal by first three distinct...
ABSTRACT We present REVEAL, a global-scale, transversely isotropic full-waveform inversion model. REVEAL builds upon the earlier construction of long-wavelength Earth (LOWE) model by lowering minimum period from 100 to 33 s and more than doubling number included earthquakes 2366. In course 305 quasi-Newton iterations, assimilated total 6,005,727 unique three-component waveforms. The method rests on combination stochastic mini-batch optimization wavefield-adapted spectral-element meshes....
We propose a new approach to full seismic waveform inversion on continental and global scales. This is based the time–frequency transform of both data synthetic seismograms with use time- frequency-dependent phase envelope misfits. These misfits allow us provide complete quantification differences between synthetics while separating amplitude information. The result an efficient exploitation information that robust quasi-linearly related Earth's structure. Thus, are usable for continental-...
We present an extension of the adjoint method that allows us to compute second derivatives seismic data functionals with respect Earth model parameters. This work is intended serve as a technical prelude implementation Newton-like optimization schemes and development quantitative resolution analyses in time-domain full waveform inversion.
We propose a new method for the quantitative resolution analysis in full seismic waveform inversion that overcomes limitations of classical synthetic inversions while being computationally more efficient and applicable to any misfit measure. The rests on (1) local quadratic approximation functional vicinity an optimal earth model, (2) parametrization Hessian terms parent function its successive derivatives (3) computation space-dependent parameters via Fourier transforms Hessian, calculated...
SUMMARY We present the theory for and applications of Hamiltonian Monte Carlo (HMC) solutions linear nonlinear tomographic problems. HMC rests on construction an artificial system where a model is treated as high-dimensional particle moving along trajectory in extended space. Using derivatives forward equations, able to make long-distance moves from current towards new independent model, thereby promoting independence, while maintaining high acceptance rates. Following brief introduction...
The mantle component of the Australian Seismological Reference Model (AuSREM) has been constructed from Australian-specific sources, primarily exploiting wealth seismic sources at regional distances around Australia recorded portable and permanent stations on continent. AuSREM is designed to bring together existing information Australia, both body wave surface studies provide a synthesis in form 3-D model that can basis for future refinement. grid based with 0.5° sampling latitude longitude,...
We present a general concept for evolutionary, collaborative, multiscale inversion of geophysical data, specifically applied to the construction first-generation Collaborative Seismic Earth Model. This is intended address limited resources individual researchers and often use previously accumulated knowledge. Model evolution rests on Bayesian updating scheme, simplified into deterministic method that honors today's computational restrictions. The scheme able harness distributed human...
Abstract We present a proof of concept for Bayesian elastic full‐waveform inversion in 2‐D. This is based on (1) Hamiltonian Monte Carlo sampling the posterior distribution, (2) computation misfit derivatives using adjoint techniques, and (3) mass matrix tuning algorithm that accounts different sensitivities seismic velocities density. apply our method to two synthetic end‐member scenarios with dimension are particularly relevant context inversion: low‐dimensional models ( ) potentially...
ABSTRACT With the potential of high temporal and spatial sampling capability utilizing existing fiber-optic infrastructure, distributed acoustic sensing (DAS) is in process revolutionizing geophysical ground-motion measurements, especially remote urban areas, where conventional seismic networks may be difficult to deploy. Yet, for DAS become an established method, we must ensure that accurate amplitude phase information can obtained. Furthermore, as spreading into many different application...
Abstract We develop and apply methods for resolution analysis in tomography, based on stochastic probing of the Hessian or operators. Key properties our are (i) low algorithmic complexity easy implementation, (ii) applicability to any tomographic technique, including full‐waveform inversion linearized ray (iii) spatial dimension inversions with a large number model parameters, (iv) computational costs that mostly fraction those required synthetic recovery tests, (v) ability quantify both...