Searched for: subject:"seismology"
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Wapenaar, C.P.A. (author)
The matrix-vector wave equation is a compact first-order differential equation. It was originally used for the analysis of elastodynamic plane waves in laterally invariant media. It has been extended by various authors for laterally varying media. Other authors derived a similar formalism for other wave phenomena. This paper starts with a...
journal article 2019
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Visser, Adriaan (author)
This work determines whether the amount of frequency components present in the data can be reduced, whilst still retaining image quality, whereas most efforts in seismological research are done in reducing spatial sampling. It is shown using a PCA on the frequency spectra of several data sets that indeed a large redundancy in frequency content...
master thesis 2018
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Meles, G.A. (author), Wapenaar, C.P.A. (author), Thorbecke, J.W. (author)
Marchenko redatuming is a novel scheme used to retrieve up- and downgoing Green's functions in an unknown medium.Marchenko equations are based on reciprocity theorems and are derived on the assumption of the existence of functions exhibiting space-time focusing properties once injected in the subsurface. In contrast to interferometry but...
journal article 2018
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Spetzler, J. (author), Dost, Bernard (author)
Induced earthquakes due to gas production have taken place in the province of Groningen in the northeast of The Netherlands since 1986. In the first years of seismicity, a sparse seismological network with large station distances from the seismogenic area in Groningen was used. The location of induced earthquakes was limited by the few and...
journal article 2017
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Ball, Justin S. (author), Godin, Oleg A. (author), Evers, L.G. (author), Lv, Cheng (author)
We investigate the spatial coherence of underwater ambient noise using a yearlong time-series measured off Ascension Island. Qualitative agreement with observed cross-correlations is achieved using a simple range-dependent model, constrained by earlier, active tomographic studies in the area. In particular, the model correctly predicts the...
journal article 2016
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Gan, S. (author), Wang, S. (author), Chen, Y. (author), Qu, S. (author), Zu, S. (author)
Direct imaging of simultaneous-source (or blended) data, without the need of deblending, requires a precise subsurface velocity model. In this paper, we focus on the velocity analysis of simultaneous-source data using the normal moveout-based velocity picking approach.We demonstrate that it is possible to obtain a precise velocity model directly...
journal article 2016
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Mulder, W.A. (author), Shamasundara, R. (author)
We consider isotropic elastic wave propagation with continuous mass-lumped finite elements on tetrahedra with explicit time stepping. These elements require higher-order polynomials in their interior to preserve accuracy after mass lumping and are only known up to degree 3. Global assembly of the symmetric stiffness matrix is a natural approach...
journal article 2016
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Wapenaar, C.P.A. (author), Thorbecke, J.W. (author), van der Neut, J.R. (author)
Green's theorem plays a fundamental role in a diverse range of wavefield imaging applications, such as holographic imaging, inverse scattering, time-reversal acoustics and interferometric Green's function retrieval. In many of those applications, the homogeneous Green's function (i.e. the Green's function of the wave equation without a...
journal article 2016
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Grobbe, N. (author), Slob, E.C. (author), Thorbecke, J.W. (author)
We study the accuracy and numerical stability of three eigenvector sets for modelling the coupled poroelastic and electromagnetic layered-Earth response. We use a known eigenvector set, its flux-normalized version and a newly derived flux-normalized set. The new set is chosen such that the system is properly uncoupled when the coupling between...
journal article 2016
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Van der Neut, J.R. (author), Vasconcelos, I. (author), Wapenaar, C.P.A. (author)
Iterative substitution of the coupled Marchenko equations is a novel methodology to retrieve the Green's functions from a source or receiver array at an acquisition surface to an arbitrary location in an acoustic medium. The methodology requires as input the single-sided reflection response at the acquisition surface and an initial focusing...
journal article 2015
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Wapenaar, C.P.A. (author), Slob, E.C. (author)
Recent work on the Marchenko equation has shown that the scalar 3-D Green’s function for a virtual source in the subsurface can be retrieved from the single-sided reflection response at the surface and an estimate of the direct arrival. Here, we discuss the first steps towards extending this result to multicomponent data. After introducing a...
journal article 2014
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Evers, L.G. (author), Brown, D. (author), Heaney, K.D. (author), Assink, J.D. (author), Smets, P.S.M. (author), Snellen, M. (author)
Atmospheric low-frequency sound, i.e., infrasound, from underwater events has not been considered thus far, due to the high impedance contrast of the water-air interface making it almost fully reflective. Here we report for the first time on atmospheric infrasound from a large underwater earthquake (Mw 8.1) near the Macquarie Ridge, which was...
journal article 2014
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Nishitsuji, Y. (author), Mori, J. (author)
We estimated source parameters of 216 intermediate-depth (65–150 km) earthquakes (Mw 4.0–7.0) in the Pacific slab beneath Japan along using Hi-net data. We made determinations of static stress drop, radiated energy and radiation efficiency, along with estimates of the whole path attenuation, to study the source scaling as a function of...
journal article 2013
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Mulder, W.A. (author), Zhebel, E. (author), Minisini, S. (author)
We analyse the time-stepping stability for the 3-D acoustic wave equation, discretized on tetrahedral meshes. Two types of methods are considered: mass-lumped continuous finite elements and the symmetric interior-penalty discontinuous Galerkin method. Combining the spatial discretization with the leap-frog time-stepping scheme, which is second...
journal article 2013
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Frank, J.G. (author)
Green's function retrieval by seismic interferometry (SI) exists in a variety of forms. Many of the applications of SI allow the creation of new seismic traces by crosscorrelating a wavefield recorded at two separate locations. The sum of this operation over multiple sources results in the creation of a new signal such that one of the recording...
master thesis 2013
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Draganov, D.S. (author), Ghose, R. (author), Heller, K. (author), Ruigrok, E.N. (author)
Application of seismic interferometry to records from receivers at the Earth’s surface from sources in wells retrieves the reflection response measured at the receivers as if from virtual sources located also at the surface. When the wavefields experience intrinsic losses during propagation, non-physical arrivals (ghosts) would appear in the...
journal article 2012
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Van der Neut, J. (author), Herrmann, F.J. (author)
Assuming that transmission responses are known between the surface and a particular depth level in the subsurface, seismic sources can be effectively mapped to this level by a process called interferometric redatuming. After redatuming, the obtained wavefields can be used for imaging below this particular depth level. Interferometric redatuming...
journal article 2012
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Van der Neut, J.R. (author), Frijlink, M. (author), Borselen, R. (author)
A common strategy for surface-related multiple elimination of seismic data is to predict multiples by a convolutional model and subtract these adaptively from the input gathers. Problems can be posed by interfering multiples and primaries. Removing multiples by multidimensional deconvolution (MDD) (inversion) does not suffer from these problems....
journal article 2012
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Ruigrok, E.N. (author)
Seismology is the study of the vibration of the Earth. Seismologists pay much attention to the main source of Earth vibration: earthquakes. But also other seismic sources, like mining blasts, ocean storms and windmills, are studied. All these sources induce seismic waves, which can eventually be recorded as ground vibrations. These seismic...
doctoral thesis 2012
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Schakel, M.D. (author), Smeulders, D.M.J. (author), Slob, E.C. (author), Heller, H.K.J. (author)
Understanding the seismoelectric interface response is important for developing seismoelectric field methods for oil exploration and environmental/engineering geophysics. The existing seismoelectric theory has never been validated systematically by controlled experiments. We have designed and developed an experimental setup in which acoustic-to...
journal article 2011
Searched for: subject:"seismology"
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