Geophysical observations at the ocean bottom

2005 ◽  
Author(s):  
J. Kasahara
Keyword(s):  
Ocean Bottom

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.

The shape of things to come — Development and testing of a new marine vibrator source

2019 ◽  
Vol 38 (9) ◽  
pp. 680-690 ◽  
Author(s):  
Benoît Teyssandier ◽  
John J. Sallas
Keyword(s):  
Seismic Source ◽  
Test Facility ◽  
Data Sets ◽  
Far Field ◽  
Ocean Bottom ◽  
Air Gun ◽  
Seismic Image ◽  
Field Radiation ◽  
Technical Issues ◽  
To Come

Ten years ago, CGG launched a project to develop a new concept of marine vibrator (MV) technology. We present our work, concluding with the successful acquisition of a seismic image using an ocean-bottom-node 2D survey. The expectation for MV technology is that it could reduce ocean exposure to seismic source sound, enable new acquisition solutions, and improve seismic data quality. After consideration of our objectives in terms of imaging, productivity, acoustic efficiency, and operational risk, we developed two spectrally complementary prototypes to cover the seismic bandwidth. In practice, an array composed of several MV units is needed for images of comparable quality to those produced from air-gun data sets. Because coupling to the water is invariant, MV signals tend to be repeatable. Since far-field pressure is directly proportional to piston volumetric acceleration, the far-field radiation can be well controlled through accurate piston motion control. These features allow us to shape signals to match precisely a desired spectrum while observing equipment constraints. Over the last few years, an intensive validation process was conducted at our dedicated test facility. The MV units were exposed to 2000 hours of in-sea testing with only minor technical issues.

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