Full Wavefield Inversion of Ocean Bottom Node Data

2013 ◽  
Author(s):  
R. Bansal ◽  
P. Routh ◽  
J. Krebs ◽  
S. Lee ◽  
A. Baumstein ◽  
...  
Keyword(s):  
Ocean Bottom ◽  
Wavefield Inversion

scholarly journals A reflection-based efficient wavefield inversion

Geophysics ◽  
2021 ◽  
pp. 1-53
Author(s):  
Chao Song ◽  
Tariq Alkhalifah
Keyword(s):  
High Resolution ◽  
Initial Velocity ◽  
Waveform Inversion ◽  
Synthetic Data ◽  
Velocity Model ◽  
Background Model ◽  
Ocean Bottom ◽  
Velocity Inversion ◽  
Velocity Models ◽  
Wavefield Inversion

Full-waveform inversion (FWI) is popularly used to obtain a high-resolution subsurface velocity model. However, it requires either a good initial velocity model or low-frequency data to mitigate the cycle-skipping issue. Reflection-waveform inversion (RWI) uses a migration/demigration process to retrieve a background model that can be used as a good initial velocity in FWI. The drawback of the conventional RWI is that it requires the use of a least-squares migration, which is often computationally expensive, and is still prone to cycle skipping at far offsets. To improve the computational efficiency and overcome the cycle skipping in the original RWI, we incorporate it into a recently introduced method called efficient wavefield inversion (EWI) by inverting for the Born scattered wavefield instead of the wavefield itself. In this case, we use perturbation-related secondary sources in the modified source function. Unlike conventional RWI, the perturbations are calculated naturally as part of the calculation of the scattered wavefield in an efficient way. As the sources in the reflection-based EWI (REWI) are located in the subsurface, we are able to update the background model along the reflection wave path. In the background velocity inversion, we calculate the background perturbation by a deconvolution process at each frequency. After obtaining the REWI inverted velocity model, a sequential FWI or EWI is needed to obtain a high-resolution model. We demonstrate the validity of the proposed approach using synthetic data generated from a section of the Sigsbee2A model. To further demonstrate the effectiveness of the proposed approach, we test it on an ocean bottom cable (OBC) dataset from the North Sea. We find that the proposed methodology leads to improved velocity models as evidenced by flatter angle gathers.

Ocean-bottom-node full-wavefield inversion for subsalt imaging: A case study from Gulf of Mexico

2021 ◽  
Author(s):  
Yaxun Tang ◽  
Xu Li ◽  
Young Ho Cha ◽  
Sunwoong Lee ◽  
Spyros Lazaratos ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Ocean Bottom ◽  
Subsalt Imaging ◽  
Wavefield Inversion

BIO-OCEANOGRAPHER, ZOOLOGIST LEV IVANOVICH MOSKALEV (04.01.1935–04.12.2020)

2020 ◽  
Vol 48 (4) ◽  
pp. 168-171
Author(s):  
E. M. Krylova ◽  
A. N. Mironov ◽  
A. V. Gebruk
Keyword(s):  
Deep Sea ◽  
Bottom Fauna ◽  
Ocean Bottom ◽  
Scientific Career ◽  
Shirshov Institute ◽  
Popular Book ◽  
Scientific Papers

The article is dedicated to the memory of L.I. Moskalev – renowned bio-oceanographer, zoologist who spent his entire scientific career at the Laboratory of Ocean Bottom Fauna. L.I. Moskalev participated in more than 30 deep-sea voyages, spent 200 hours diving in manned submersibles “Pisces” and “Mir”, published about 100 scientific papers and a popular book «Masters of the Deep» (2005). Colleagues will remember Lev Moskalev – an extraordinary and deep person and a true patriot of the Laboratory and P.P. Shirshov Institute of Oceanology

scholarly journals Analysis of Ocean Bottom Pressure Anomalies and Seismic Activities in the MedRidge Zone

2021 ◽  
Vol 13 (7) ◽  
pp. 1242
Author(s):  
Hakan S. Kutoglu ◽  
Kazimierz Becek
Keyword(s):  
Time Series ◽  
Mass Change ◽  
Ocean Bottom ◽  
Bottom Pressure ◽  
Vertical Movements ◽  
Ocean Bottom Pressure ◽  
Continuous Mass ◽  
Mediterranean Ridge Accretionary Complex ◽  
Gravity Recovery ◽  
Periodic Components

The Mediterranean Ridge accretionary complex (MAC) is a product of the convergence of Africa–Europe–Aegean plates. As a result, the region exhibits a continuous mass change (horizontal/vertical movements) that generates earthquakes. Over the last 50 years, approximately 430 earthquakes with M ≥ 5, including 36 M ≥ 6 earthquakes, have been recorded in the region. This study aims to link the ocean bottom deformations manifested through ocean bottom pressure variations with the earthquakes’ time series. To this end, we investigated the time series of the ocean bottom pressure (OBP) anomalies derived from the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) satellite missions. The OBP time series comprises a decreasing trend in addition to 1.02, 1.52, 4.27, and 10.66-year periodic components, which can be explained by atmosphere, oceans, and hydrosphere (AOH) processes, the Earth’s pole movement, solar activity, and core–mantle coupling. It can be inferred from the results that the OBP anomalies time series/mass change is linked to a rising trend and periods in the earthquakes’ energy time series. Based on this preliminary work, ocean-bottom pressure variation appears to be a promising lead for further research.

Typhoon-Induced Microseisms around the South China Sea

2020 ◽  
Vol 91 (6) ◽  
pp. 3454-3468
Author(s):  
Seongjun Park ◽  
Tae-Kyung Hong
Keyword(s):  
South China Sea ◽  
South China ◽  
Bottom Topography ◽  
Pressure Change ◽  
Ocean Waves ◽  
The South China Sea ◽  
Ocean Bottom ◽  
The South ◽  
China Sea ◽  
Regional Factors

Abstract Microseisms in frequencies of 0.05–0.5 Hz are a presentation of solid earth response to the ocean waves that are developed by atmospheric pressure change. The South China Sea provides a natural laboratory with a closed ocean environment to examine the influence of regional factors on microseism development as well as the nature of microseisms. The microseisms induced by typhoons crossing over the South China Sea are investigated. Typhoons are typical transient sources of varying strengths and locations. Primary microseisms develop nearly stationary in the northeastern South China Sea for most typhoons, suggesting effective environment for excitation of primary microseisms. Typhoon-induced secondary microseisms develop around the typhoon paths with time delays varying up to one day. Typhoon-induced microseism amplitudes are proportional to the ocean-wave amplitudes in the source regions, decaying with distance. Ocean waves develop following the typhoons for days. The dominant frequency of typhoon-induced microseisms increases with time due to the influence of dispersive ocean waves. The microseisms are affected by regional factors including crustal structures, coastal geometry, ocean depth, and ocean-bottom topography.

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