Target-oriented least-squares reverse-time migration with Marchenko redatuming and double-focusing: Field data application

Recently, the focus of reflection seismologists has shifted to applications where a high-resolution image of the subsurface is required. Least-Squares Reverse-Time Migration (LSRTM) is a common tool used to compute such images. Still, its high computational costs have led seismologists to use target-oriented LSRTM for imaging only a small target...

Reciprocity and Representations for Wave Fields in 3D Inhomogeneous Parity-Time Symmetric Materials

Inspired by recent developments in wave propagation and scattering experiments with parity-time (PT) symmetric materials, we discuss reciprocity and representation theorems for 3D inhomogeneous PT-symmetric materials and indicate some applications. We start with a unified matrix-vector wave equation which accounts for acoustic, quantum...

An Algorithm to Minimize the Zero-Flow Error in Transit-Time Ultrasonic Flow Meters

Transit-time ultrasonic flow meters are widely used in industry to measure fluid flow. In practice ultrasonic flow meters either show a zero-flow error or suffer from a significant random error due to a limited signal-to-noise ratio, requiring a significant amount of averaging to achieve good precision. This work presents a method that minimizes...

Velocity-independent Marchenko focusing in time- and depth-imaging domains for media with mild lateral heterogeneity

The Marchenko method retrieves Green's functions between the acquisition surface and any arbitrary point in the medium. The process generally involves solving an inversion starting with an initial focusing function, e.g., a direct-wave Green's function from the desired subsurface position, typically obtained using an approximate velocity...

Marchenko method for monitoring induced seismicity with virtual receivers

The Marchenko method can be used to retrieve Green’s functions (including multiple scattering) between virtual sources in the subsurface and physical receivers at the surface or virtual receivers in the subsurface. Here we discuss a variant of the Marchenko method which retrieves the response between physical sources and virtual receivers in the...

Marchenko imaging: Imaging with primaries, internal multiples, and free-surface multiples

Recent work on retrieving the Green’s function with the Marchenko equation shows how these functions for a virtual source in the subsurface can be obtained from reflection data. The response to the virtual source is the Green’s function from the location of the virtual source to the surface. The Green’s function is retrieved using only the...

Mandatory volunteer work as fair reciprocity for unemployment and social benefits

Modern welfare policies are increasingly based on notions of reciprocity. Citizens on welfare benefits have to do something in return, e.g. volunteer work. Notwithstanding general public support, social philosophers have been critical on ‘mandatory’ activities in community programmes. So far, the participants themselves have scarcely been asked...

Marchenko imaging

Traditionally, the Marchenko equation forms a basis for 1D inverse scattering problems. A 3D extension of the Marchenko equation enables the retrieval of the Green’s response to a virtual source in the subsurface from reflection measurements at the earth’s surface. This constitutes an important step beyond seismic interferometry. Whereas seismic...

Data-driven wavefield focusing and imaging with multidimensional deconvolution: Numerical examples for reflection data with internal multiples

Standard imaging techniques rely on the single scattering assumption. This requires that the recorded data do not include internal multiples, i.e., waves that have bounced multiple times between reflectors before reaching the receivers at the acquisition surface. When multiple reflections are present in the data, standard imaging algorithms...

Three-dimensional Marchenko equation for Green's function retrieval “beyond seismic interferometry”

In recent work we showed with heuristic arguments that the Green's response to a virtual source in the subsurface can be obtained from reflection data at the surface. This method is called “Green's function retrieval beyond seismic interferometry”, because, unlike in seismic interferometry, no receiver is needed at the position of the virtual...

Granularity in reciprocity

Witnessing in merging biological, social and algorithmic realities is crucial to trust, as modelled in the YUTPA framework. Being witness and bearing witness is fundamental to human interaction. System participation in human communities of practice challenges the notion of witnessing and therefore the ability to build trust. Nevertheless,...

Rigorous simulations of emitting and non-emitting nano-optical structures

In the next decade, several applications of nanotechnology will change our lives. LED lighting is about to replace the common light bulb. The main advantages are its energy efficiency and long lifetime. LEDs can be much more efficient, when part of the emitted light that is currently trapped in the device, could be radiated out of the device....

Seismic and electromagnetic interferometry: Retrieval of the earth's reflection response using crosscorrelation

One of the goals of exploration geophysics is to obtain an image of the subsurface. In petroleum exploration and near-surface geophysics, this is best achieved using reflected waves. For this, a controlled seismic or electromagnetic source is placed at the surface, activated, and the wavefields that it creates are recorded at the surface after...

Removing Love waves from shallow seismic SH-wave data

Geophysical exploration measurements are used to obtain an image of the geological structures of the subsurface, as detailed as possible. To this end, a wavefield is generated by a seismic source. This wavefield propagates through the subsurface, and will partly reflect on boundaries between layers with contrasting properties, and it will partly...

Wavefields and reciprocity: Proceedings of a symposium held in honour of Professor dr. A.T. de Hoop, November 20-21, 1996, Delft, the Netherlands