Zobrazeno 1 - 10
of 177
pro vyhledávání: '"Lasse Amundsen"'
The viscoacoustic Green's function for the Helmholtz equation in a velocity gradient interface model
Autor:
Lasse Amundsen, Bjørn Ursin
Publikováno v:
Geophysical Journal International. 233:1531-1545
SUMMARY In viscoacoustically stratified media where the density is constant, 3-D wave propagation in the frequency–radial wavenumber domain is governed by the Helmholtz equation. In the case that the model is a velocity gradient interface where the
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::1372aeacfa264552964490a072811f5e
https://doi.org/10.1093/gji/ggad007
https://doi.org/10.1093/gji/ggad007
Autor:
Lasse Amundsen, Bjørn Ursin
Publikováno v:
GEOPHYSICS. 88:WA1-WA12
For 1D acoustic wave propagation in the frequency domain, the complex nonlinear Riccati differential equation describes the dependence of the plane-wave reflection response in depth, defined as the upgoing part of the wavefield divided by the downgoi
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::9cf400a2b8a9fd6e3e29920d30de5707
https://doi.org/10.1190/geo2022-0186.1
https://doi.org/10.1190/geo2022-0186.1
Publikováno v:
The Journal of the Acoustical Society of America. 152:659-666
A weak scattering model that allows prediction of the one-dimensional acoustic plane wave primary reflection response from an impedance gradient interface is described. The velocity and density gradient profiles are represented by a smooth approximat
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::395eaa35b89c98a40246574babac176d
https://doi.org/10.1121/10.0012885
https://doi.org/10.1121/10.0012885
Autor:
Lasse Amundsen, Bjørn Ursin
Publikováno v:
GEOPHYSICS. 87:R231-R244
An amplitude variation with angle (AVA) inversion method is presented for estimating density and velocities of a stratified elastic medium from reflection seismograms in the intercept time-horizontal slowness domain. The elastic medium parameters are
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::738fb231a6cbb7bcd54274444766deb3
https://doi.org/10.1190/geo2021-0338.1
https://doi.org/10.1190/geo2021-0338.1
Autor:
Lasse Amundsen, Bjørn Ursin
Publikováno v:
GEOPHYSICS. 87:T15-T28
Many modeling techniques have been developed to find the acoustic and elastic responses of a stack of plane layers to a plane spectral wave. For an elastic medium bounded above by an acoustic half-space, the acoustic wave propagator matrix modeling m
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::494ad7799742d99ba3c45809a035a33c
https://doi.org/10.1190/geo2021-0305.1
https://doi.org/10.1190/geo2021-0305.1
Autor:
Lasse Amundsen
Publikováno v:
GEOPHYSICS. 86:R849-R864
A theory is presented for estimating the background velocity and density of an acoustic stratified medium by iterative least-squares waveform inversion in the frequency-horizontal slowness domain of low-frequency precritical reflection incidence seis
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::1c5f77c036b9c5f2c3bc9dbe0f3e7e9f
https://doi.org/10.1190/geo2021-0165.1
https://doi.org/10.1190/geo2021-0165.1
Autor:
Lasse Amundsen
Publikováno v:
GEOPHYSICS. 86:R351-R368
Least-squares full-waveform inversion (FWI) is considered in the frequency domain for a set of noise-free observations of time length [Formula: see text] at the surface obeying the 1D wave equation, with a known source. The initial model is of consta
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::08427e9cffea46c8c5716676ef3e0584
https://doi.org/10.1190/geo2020-0257.1
https://doi.org/10.1190/geo2020-0257.1
Autor:
Lasse Amundsen
Publikováno v:
First International Meeting for Applied Geoscience & Energy Expanded Abstracts.
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::cde425b656f6cfca3beef9f06d1c0717
https://doi.org/10.1190/segam2021-3581182.1
https://doi.org/10.1190/segam2021-3581182.1
Publikováno v:
P61-P71
Geophysics
Geophysics
In marine seismic acquisition, the enhancement of frequency amplitudes below 5 Hz is of special interest because it improves imaging of the subsurface. The frequency content of the air gun, the most commonly used marine seismic source, is mainly cont
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::6fcb9af0df73455b8a3c6a54c7ab53aa
https://doi.org/10.1190/geo2018-0687.1
https://doi.org/10.1190/geo2018-0687.1
Autor:
Lasse Amundsen, Ørjan Pedersen
Publikováno v:
GEOPHYSICS. 84:T47-T58
Time integration of wave equations can be carried out with explicit time stepping using a finite-difference (FD) approximation. The wave equation is the partial differential equation that governs the wavefield that is solved for. The FD approximation
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::972b0ed42b5c2735a7eb03f351f2f58c
https://doi.org/10.1190/geo2018-0281.1
https://doi.org/10.1190/geo2018-0281.1