On spectral and amplitude properties of first‐ and zeroth‐ order head waves, and implications for geoacoustic inversion

2005 ◽  
Vol 118 (3) ◽  
pp. 1969-1969 ◽  
Author(s):  
Jee Woong Choi ◽  
Peter H. Dahl
Keyword(s):  
Zeroth Order ◽  
Geoacoustic Inversion ◽  
Head Waves

Observations of zeroth‐order head waves in the Yellow Sea

2005 ◽  
Vol 118 (3) ◽  
pp. 1969-1970
Author(s):  
Peter H. Dahl ◽  
Jee Woong Choi
Keyword(s):  
Yellow Sea ◽  
The Yellow Sea ◽  
Zeroth Order ◽  
Head Waves

scholarly journals Geoacoustic Estimation of the Seafloor Sound Speed Profile in Deep Passive Margin Setting Using Standard Multichannel Seismic Data

2021 ◽  
Vol 9 (12) ◽  
pp. 1423
Author(s):  
Ernst Uzhansky ◽  
Omri Gadol ◽  
Guy Lang ◽  
Boris Katsnelson ◽  
Shelly Copel ◽  
...  
Keyword(s):  
Deep Water ◽  
Seismic Data ◽  
Sound Speed ◽  
Sound Propagation ◽  
Passive Margin ◽  
Seismic Profiles ◽  
Geoacoustic Inversion ◽  
Margin Setting ◽  
Receiver Array ◽  
Head Waves

Seafloor geoacoustic properties are important in determining sound propagation in the marine environment, which broadly affects sub-sea activities. However, geoacoustic investigation of the deep seafloor, which is required by the recent expansion of deep-water operations, is challenging. This paper presents a methodology for estimating the seafloor sound speed, c0, and a sub-bottom velocity gradient, K, in a relatively deep-water-compacting (~1000 m) passive-margin setting, based on standard commercial 2D seismic data. Here we study the seafloor of the southeastern Mediterranean margin based on data from three commercial seismic profiles, which were acquired using a 7.2 km-long horizontal receiver array. The estimation applies a geoacoustic inversion of the wide-angle reflections and the travel times of the head waves of bending rays. Under the assumption of a constant positive K, the geoacoustic inversion converges to a unique set of parameters that best satisfy the data. The analysis of 24 measurement locations revealed an increase in the average estimates of c0 from 1537 ± 13 m s−1 to 1613 ± 12 m s−1 for seafloor depths between ~1150 m and ~1350 m. K ranged between 0.75 and 0.85 m s−1 with an average of 0.80 ± 0.035 s−1. The parameters were consistent across the different locations and seismic lines and they match the values that were obtained through depth-migration-velocity analysis and empiric relations, thereby validating our estimation methodology.

Oblique-incidence Reflectivity Difference (OI-RD) and Leed Studies of Adsorption and Growth of Xe on Nb(110)

2003 ◽  
Vol 780 ◽  
Author(s):  
P. Thomas ◽  
E. Nabighian ◽  
M.C. Bartelt ◽  
C.Y. Fong ◽  
X.D. Zhu
Keyword(s):  
Transition Layer ◽  
Layer Growth ◽  
Flow Mode ◽  
Layer By Layer ◽  
Zeroth Order ◽  
Step Flow ◽  
Low Energy Electron Diffraction ◽  
Oriented Film ◽  
Low Energy Electron

AbstractWe studied adsorption, growth and desorption of Xe on Nb(110) using an in-situ obliqueincidence reflectivity difference (OI-RD) technique and low energy electron diffraction (LEED) from 32 K to 100 K. The results show that Xe grows a (111)-oriented film after a transition layer is formed on Nb(110). The transition layer consists of three layers. The first two layers are disordered with Xe-Xe separation significantly larger than the bulk value. The third monolayer forms a close packed (111) structure on top of the tensile-strained double layer and serves as a template for subsequent homoepitaxy. The adsorption of the first and the second layers are zeroth order with sticking coefficient close to one. Growth of the Xe(111) film on the transition layer proceeds in a step flow mode from 54K to 40K. At 40K, an incomplete layer-by-layer growth is observed while below 35K the growth proceeds in a multilayer mode.

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