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Dissertations / Theses on the topic 'Ocean bottom'

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Published: 4 June 2021

Last updated: 30 July 2024

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1

Dougherty, Martin Eugene. "Ocean bottom seismic scattering." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/52938.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, and Woods Hole Oceanographic Institution, 1990.
GRSN 589503
Includes bibliographical references (p. 299-301).
by Martin Eugene Dougherty.
Ph.D.

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2

Jones, Trevor N. "Ocean bottom modeling for ray acoustics." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/26660.

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3

Robertson, Candace Joanne. "Ocean bottom simulation using fractal geometry." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/26661.

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4

Gontz, Allen M. "Evolution of Seabed Pockmarks in Penobscot Bay, Maine." Fogler Library, University of Maine, 2002. http://www.library.umaine.edu/theses/pdf/GontzAM2002.pdf.

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5

Reiter, Edmund. "Imaging of large offset ocean bottom seismic data." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/54967.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1991.
Includes bibliographical references (leaves 139-146).
by Edmund C. Reiter.
Ph.D.

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6

Tang, Dajun. "Acoustic wave scattering from a random ocean bottom." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/13908.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, and Woods Hole Oceanographic Institution, 1991.
Includes bibliographical references (leaves 123-130).
Dajun Tang.
Ph.D.

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7

Howze, Sarah C. "A Birdhouse at the Bottom of the Ocean." ScholarWorks@UNO, 2013. http://scholarworks.uno.edu/td/1637.

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8

Quijano, Jorge. "Radiative Transfer Theory Applied to Ocean Bottom Modeling." PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/516.

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Research on the propagation of acoustic waves in ocean bottom sediment is of interest for active sonar applications such as target detection and remote sensing. Currently, all seabed scattering models available in the literature are based on the full solution of the wave equation, which sometimes leads to mathematically intractable problems. In the electromagnetics community, an alternative formulation that overcomes some of this complexity is radiative transfer theory, which has established itself as an important technique for remote sensing. In this work, radiative transfer (RT) theory is proposed for the first time as a tool for the study of seabed acoustic scattering. The focus of this work is the development of a complete model for the interaction of acoustic energy with water-saturated sediments. The general geometry considered in this study consists of multiple elastic layers containing random distributions of inhomogeneities. The accuracy of the proposed model is assessed by rigorous experimental work, with data collected from random media in which acoustic properties such as the concentration and size of scatterers, background material, and the presence of elastic boundaries are controlled parameters. First, the ultrasound RT model is implemented for layers of finite thickness. The range of applicability of the proposed model is then illustrated using scaled experiments conducted at the Northwest Electromagnetics and Acoustics Research Laboratory (NEAR-Lab). Next, the model is applied to field data collected in a region with gassy sediments and compared to the formulation originally used to explain these data. Finally, insight into the emerging area of study of the time-dependent RT formulation is presented, and its role in the representation of finite broadband pulses is discussed.

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9

Susanto, Raden Dwi 1963. "Spatial coherence and rough bottom scattering in shallow water." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/36003.

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10

Dorfman, Yevgeniy Yakov 1967. "Bistatic scattering of acoustic waves from a rough ocean bottom." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/49618.

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11

Li, Dan 1969. "Low-frequency bottom backscattering data analysis using multiple constraints beamforming." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36060.

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12

Adcock, Susan T. "A parameterisation of geostrophic eddies over variable bottom topography." Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314318.

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13

Salstrand, Daniel Koewing. "A mathematical model for magma-hydrothermal systems in the oceanic crust." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/25700.

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14

Rodriguez, Suarez Carlos. "Advanced marine seismic methods, ocean-bottom and vertical-cable analyses." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0023/NQ49533.pdf.

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15

Makowski, Jessica. "Understanding Transport Variability of the Antarctic Circumpolar Current Using Ocean Bottom Pressure." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4915.

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Previous studies have suggested that ocean bottom pressure (OBP) can be used to measure the transport variability of the Antarctic Circumpolar Current (ACC). The OBP observations from the Gravity Recovery and Climate Experiment (GRACE) are used to calculate transport along the choke point between Antarctica and Australia. Statistical analysis will be conducted to determine the uncertainty of the GRACE observations using a simulated data set. There has been some evidence to suggest that Southern Hemisphere winds and the Southern Annular Mode (SAM) or the Antarctic Oscillation (AAO) play a significant role in accelerating/decelerating ACC transport, along with some contribution from buoyancy forcing. We will examine whether average zonal wind stress, wind stress curl, local zonal winds, or the SAM are representative of the low frequency zonal mass transport variability. Preliminary studies suggest that seasonal variation in transport across the Australia-Antarctica choke point is driven by winds along and north of the northern front of the ACC, the Sub Tropical front (STF). It also appears that interannual variations in transport are related to wind variations centered south of the Sub Antarctic Front (SAF). We have observed a strong negative correlation/positive correlation across the STF of the ACC in the Indian Ocean, which suggests wind stress curl may also be responsible for transport variations.

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16

Bowers, Colleen Marie. "Seafloor ripples created by waves from hurricane Ivan on the West Florida Shelf." Thesis, Online version of original thesis, 2006. http://handle.dtic.mil/100.2/ADA471865.

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Thesis (M.S.)--Joint Program in Oceanography/ Applied Ocean Science and Engineering, Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution, 2006.
"September 2006." Description based on title screen as viewed on June 8, 2010. DTIC Descriptor(s): Ocean Waves, Water Waves, Ripples, Side Looking Sonar, Ocean Bottom, Frequency, Detection, Sites, Theses, Depth, Buried Objects, Mines(Ordnance), Secondary Waves, Scientists, Offshore, Sediments, Acoustic Data, Data Acquisition, Storms, Sand, Motion, Models, Surface Waves, Angles Includes bibliographical references (leaves 94-96). Also available in print.

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17

Sidler, Rolf. "Reflection of seismic waves from attenuating and anisotropic ocean bottom sediments /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17891.

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18

Miller, Thomas Edward S. M. Massachusetts Institute of Technology. "Real time bottom reverberation simulation in deep and shallow ocean environments." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/103576.

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Thesis: S.M., Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (page 77).
Due to the costs involved and time required to perform experiments at sea, it is important to provide accurate simulations of the ocean environment. Using the ray tracing code, BELLHOP, the Mission Oriented Operating Suite (MOOS), methods outlined by the Naval Research Laboratory (NRL) for bottom reverberation, and MATLAB, a model will be developed to incorporate the effects of bottom reverberation into the BELLHOP suite of code. This will be accomplished by using BELLHOP to generate a ray trace and eigen ray file. Then a MATLAB script will take the BELLHOP information and calculate the reverberation level using the NRL model by measuring the amplitude and reverberation at a receiver array simulated on the ocean floor. These reverberation values will then be used to determine the reverberation level at the source due to these bottom interactions. Testing of the simulation will include deep and shallow ocean profiles and multiple sound speed profiles (SSP). Following this testing, the goal is to implement the model in existing C++ code used for the testing of AUV systems. The ability to accurately model the ocean will not only allow for testing of autonomy code in the laboratory, but also make it possible to refine and calibrate code making ship time more efficient.
by Thomas Edward Miller.
S.M.

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19

Golden, Charles Edward. "Investigation of oceanic spreading center hydrothermal processes using ocean bottom seismometers /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2000. http://wwwlib.umi.com/cr/ucsd/fullcit?p3035910.

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20

Ward, Nikole S. "Investigation of Near-Bottom Current Characteristics Along an Open-Ocean Coast." UNF Digital Commons, 2018. https://digitalcommons.unf.edu/etd/827.

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Near-bottom current data was collected over a period of 8 years at the U.S. Army Corps of Engineers Field Research Facility in Duck, North Carolina. This data set consisted of currents measured up to three elevations above the bottom at deployment depths of 5 meters, 8 meters and 13 meters, as well as continuous real-time wind and wave data collected at the pier. The data was collated, quality checked and analyzed to define a climatology of near bottom currents along the study area using current moments. This data set had previously never been available for analysis due to the large amount of effort required to take old computer files and subject them to rigorous processing and quality control. The analyses conducted in this thesis represent the first ever attempt to analyze this type of data on this scale. An initial monthly investigation was conducted at the 8-meter site to determine driving forces of mean currents, and a more in depth seasonal investigation was subsequently completed to quantify the relationships between the cross-shore currents and different forcing mechanisms. Once seasonal trends were established relating mean current to incident wave height, wave steepness and wind speed, an examination of some significant historical events within the study was completed to help link cross-shore current behavior to storm events. Three separate nor’easter events and three significant hurricanes (Bonnie, Dennis and Floyd) were found to produce significant cross-shore currents at the study site. Similar to previous nearshore studies, it was found that the occurrence of onshore winds and wave heights greater than about 1.5 meters produce near-bottom mean currents moving in the offshore direction. Alternatively, when winds are blowing in the offshore direction, waves are still propagating onshore, but mean near-bottom currents tend to be directed in the onshore direction. The importance of vertical current structure within the water column was apparent, even though the instruments’ measurement elevations were all located within the bottom boundary layer. In contrast to the assumption of zero cross-shore velocity at near-coast sites implicit in two-dimensional depth averaged models used in most coastal engineering studies today, it was found that cross-shore near-bottom currents are rarely ever zero. Depth-averaged models inherently assume that currents move as a single block of water throughout the water column. The physical impacts of this misrepresentation of nearshore currents become very significant in predictions of many coastal phenomena, such as storm surge, sediment transport and wave conditions at the coast. When wave heights exceed 2 meters, mean currents tend to be between 0.2-0.5 meters per second in both the onshore and offshore direction, in the opposite direction of the primary forcing at the surface. In some instances, wave heights are low with strong mean currents while wind speeds are high, indicating the driving force in this situation is wind speed. However, there are cases where wave heights are large and mean current values are relatively low, which requires further investigation. Future work will include investigating phenomena that are related to higher-order odd moments of the current statistics, since they are expected to play a critical role in improved understanding of the physics within the nearshore and are very much needed for predictions of coastal evolution under future sea level rise and potential climate change.

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21

Casanovas, Revilla Clara Ines. "Experimental investigation of the interaction of bottom towed fishing gears and the seabed." Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=238973.

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22

Martinho, Antonio S. "Sensitivity studies using multi-region and open boundary conditions for terrain bottom following ocean models." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Mar%5FMartinho.PhD.pdf.

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23

Frank, Donya P. "Wave-Current Bottom Boundary Layer Interactions." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1229087949.

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24

Ainslie, Michael Anthony. "The sound pressure field in the ocean due to bottom interacting paths." Thesis, University of Southampton, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314950.

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25

Sears, Timothy John. "Elastic full waveform inversion of multi-component ocean-bottom cable seismic data." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613186.

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26

Li, Dan 1969. "Modeling of monostatic bottom backscattering from three-dimensional volume inhomogeneities and comparisons with experimental data." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/43542.

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27

Tempera, Fernando. "Benthic habitats of the extended Faial Island Shelf and their relationship to geologic, oceanographic and infralittoral biologic features /." St Andrews, 2008. http://hdl.handle.net/10023/726.

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28

Gosnell, Sawyer Ross. "Numerical modeling of induced diffuse flow in seafloor hydrothermal system." Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-08252006-125256/.

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29

Hankins, Jeremy R. "A study of the vertical component of ocean floor vibrations in two geographical chokepoints." Thesis, Monterey, California: Naval Postgraduate School, 2017. http://hdl.handle.net/10945/52985.

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Reissued 30 May 2017 with Second Reader’s non-NPS affiliation added to title page.
Approved for public release; distribution is unlimited
The purpose of this thesis is to characterize typical levels of vibrational noise on the ocean floor to ascertain the vibration's effect on possible future bottom mounted sensors. The data used for this thesis was obtained from publicly available recorded information from four ocean bottom seismometers (OBS). The OBSs were located in two geographical choke points: the Luzon Strait and west of the Strait of Juan de Fuca. These highly trafficked choke points were considered to be a good representation of where these experimental bottom mounted sensors might be located should they be built. Unix-based seismic processing software available from the Incorporated Research Institutions for Seismology (IRIS) proved essential to obtaining calibrated data, and the methodology used to get the calibrated data is discussed in detail. The results showed that one OBS out of the four was highly variable, with decibel levels varying widely from day to day. The other OBSs remained fairly consistent. In addition, there were no common discrete frequencies between sensors that were in the same geographic area. Recommended future research involves the study of environmental effects on the OBSs, additional research to correlate the results observed in the Luzon Strait, and a look into the electronic noise floors of the OBSs used.
Lieutenant Commander, United States Navy

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30

Pruis, Matthew J. "Energy and volume flux into the deep ocean : examining diffuse hydrothermal systems /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/10990.

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31

Chandana, K. R., Ravi Bhushan, and A. J. T. Jull. "Evidence of Poor Bottom Water Ventilation during LGM in the Equatorial Indian Ocean." FRONTIERS MEDIA SA, 2017. http://hdl.handle.net/10150/626606.

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Multi-proxy approach for the reconstruction of paleo-redox conditions is attempted on a radiocarbon (C-14) dated sediment core near the equatorial Indian Ocean. Based on the behavior and distribution of redox sensitive and productivity proxies, study demonstrates prevalence of anoxic bottom water conditions during LGM due to poorly ventilated bottom waters augmented by high surface productivity resulting in better preservation of organic carbon (OC). During early Holocene, the equatorial Indian Ocean witnessed high sedimentation rates resulting in high organic carbon (OC) with depleted redox sensitive elements thereby causing better preservation of OC. The study underscores poor bottom water ventilation during LGM and preservation of OC as a result of high sedimentation rate in early Holocene.

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32

Paliatsos, Demetrios. "Computer studies of sound propagation in a wedge-shaped ocean with penetrable bottom." Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/25777.

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Approved for public release; distribution is unlimited.
The sound distribution everywhere within a wedge-shaped fluid overlying either a slow or a fast bottom was studied. Collecting all the results of the previous works in this area and overviewing them has been the primary purpose. All the cases reported earlier have been studied, and some new ones have been added. The variation of the transition point distance with the shore distance as a variable was observed. In addition, the isopressure patterns were verified by calculating the pressure amplitudes in axial direction. Keywords: Underwater acoustics; Three-dimensional underwater sound transmission; Ocean bottom slope; Acoustic fields; Computerized simulation; Shallow water. Theses

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33

Steele, Edward C. C. "Three-dimensional turbulence characteristics of the bottom boundary layer of the coastal ocean." Thesis, University of Plymouth, 2015. http://hdl.handle.net/10026.1/3459.

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The form and dynamics of ocean turbulence are critical to all marine processes; biological, chemical and physical. The three-dimensional turbulence characteristics of the bottom boundary layer of the coastal ocean are examined using a series of 29,991 instantaneous velocity distributions. These data, recorded by a submersible 3D-PTV system at an elevation of 0.64 m above the seabed, represent conditions typical of moderate tidal flows in the coastal ocean. A complexity associated with submersible 3D-PTV in the coastal ocean is that gaps and noise affect the accuracy of the data collected. To accommodate this, a new Physics-Enabled Flow Restoration Algorithm has been tested for the restoration of gappy and noisy velocity measurements where a standard PTV or PIV laboratory set-up (e.g. concentration / size of the particles tracked) is not possible and the boundary and initial conditions are not known a priori. This is able to restore the physical structure of the flow from gappy and noisy data, in accordance with its hydrodynamical basis. In addition to the restoration of the velocity flow field, PEFRA also estimates the maximum possible deviation of the output from the true flow. 3D-PTV measurements show coherent structures, with the hairpin-like vortices highlighted in laboratory measurements and numerical modelling, were frequently present within the logarithmic layer. These exhibit a modal alignment of 8 degrees from the mean flow and a modal elevation of 27 degrees from the seabed, with a mean period of occurrence of 4.3 sec. These appear to straddle sections of zero-mean along-stream velocity, consistent with an interpretation as packets. From these measurements, it is clear that data collected through both laboratory and numerical experiments are directly applicable to geophysical scales – a finding that will enable the fine-scale details of particle transport and pollutant dispersion to be studied in future. Conditional sampling of the Reynolds shear stress (without using Taylor’s hypothesis) reveals that these coherent structures are responsible for the vertical exchange of momentum and, as such, are the key areas where energy is extracted from the mean flow and into turbulence. The present study offers the first assessment of the magnitude of the errors associated with assuming isotropy on shear-based sensors of the TKE dissipation rate and its consequential effect on the Kolmogorov microscale using 3D-PTV data from the bottom boundary layer of the coastal ocean. The results indicate a high degree of spatial variability associated with the low conditions. The averaged data supports the validity of measurements obtained by horizontal and vertical profilers, however along-stream velocity derivatives underestimate the TKE dissipation rate by more than 40% – a factor of two higher than for the equivalent cross-stream and vertical estimates. This has important implications for the deployment of these sensors and the subsequent interpretation of higher-order statistics. Finally, the data have been processed to test four popular sub-grid scale (SGS) stress models and SGS dissipation rate estimates for Large-Eddy Simulations using these in situ experimental data. When the correlation and SGS model coefficients are assessed, the nonlinear model represents the best stress models to use for the present data, consistent with the substantial anisotropy and inhomogeneity associated with these flows. The detailed measurement and analysis of coherent structures in the coastal ocean undertaken therefore supports the development of numerical models and assists with the understanding of all marine processes.

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34

Kjelldorff, Maria. "Water Current Measurements using Oceanographic Bottom LanderLoTUS?" Thesis, KTH, Marina system, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-261697.

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oTUS is a Long Term Underwater Sensing, bottom landing, node for observations of ocean water temperatures. LoTUS measures temperature (moored to the seaﬂoor) according to a spec-iﬁed time schedule until, at the end of the mission, it surfaces to transmit the collected data to on shore recipients using an Iridium link. The paper presents an extension of the sensing capability to include water current velocity (speed and direction) using a robust, reliable and inexpensive Eulerian method. The method is based on the "tilting stick" principle where a combination of inertia measurement data and magnetic sensor data is used. The paper discusses the principal technique, the modeling of the system, practical considerations, and optimization of the setup for speciﬁc ﬂow conditions along with verifying experimental data.

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35

Lin, Zaibin. "Integrated numerical model for wave induced seabed response around offshore structures." Thesis, University of Aberdeen, 2017. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=232272.

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Seabed stability in the vicinity of those offshore structure, which has been one of the particular concerns in engineering practice, can be compromised by the action of energetic waves. This project investigates the mechanisms of wave-induced soil response and liquefaction in a porous seabed near offshore structures. For this purpose both 2-Dimensional (2-D) and 3-Dimensional (3-D) integrated Wave-Seabed-Structure Interaction (WSSI) models have been developed within the project. They were used to simulate the effect of nonlinear wave-structure interaction on dynamic soil response in the neighbourhood of offshore pipelines, mono-pile structures, and multi-cylinder structures. Prior to applying the proposed WSSI models to practical engineering cases, several validations, mainly including wave and soil validations, were conducted. Excellent agreements between numerical and experimental results indicate the capacity of proposed WSSI models to simulate nonlinear wave-induced seabed response around offshore structures. Hereafter, the verified WSSI models are adopted to explore the mechanism of storm wave-induced soil response near offshore structures. The study of the offshore pipeline partially or fully buried in the seabed has shown that the leewake vortex can be sufficiently avoided with enough embedment, which also leads to lower possibility of the onset of scour in adjacent area of pipeline and the reduction of possible momentary liquefaction depth under pipeline bottom. Nonlinear wave-induced seabed response around a mono-pile structure, was investigated using the 3-D WSSI model developed in OpenFOAM, which allows to run numerical WSSI simulations in parallel. It was shown that, for waves propagating in a given longitudinal direction, the liquefaction occurs with greater depth at the lateral sides of mono-pile structure than at the front and back sides of mono-pile structure. Increasing penetration depth of the mono-pile structure slightly reduces the adjacent liquefaction depth. By adopting the same 3-D WSSI model, the numerical investigation of wave-induced soil response in the proximity of a multi-cylinder structure has been conducted. As found in the analysis by using same wave parameters in the case of a mono-pile structure, the nonlinear interaction between waves and multi-cylinder structure may significantly alter the distribution of liquefaction depth around each cylinder, compared to that for a single cylinder. Moreover, considering the effect of incident wave angles, such as 0° and 45° wave headings, it can be noted that the downstream cylinders are better protected from liquefaction threat due to the presence of upstream cylinders.

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36

Farmer, Andrew Scott. "Bottom albedo derivations using hyperspectral spectrometry and multispectral video." [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001054.

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37

Morrison, Archie Todd. "Development of the BASS rake acoustic current sensor : measuring velocity in the continental shelf wave bottom boundary layer." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/43470.

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38

Palinkas, Cynthia. "Temporal and spatial patterns of modern shelf sedimentation in the Adriatic Sea /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/10986.

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39

Duncan, Catherine Schuur. "Latest Quaternary stratigraphy and seafloor morphology of the New Jersey continental shelf /." Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3008320.

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40

Gilbert, Lisa A. "Shallow crustal structure of Axial Seamount : geophysical inversion of sea surface and near seafloor gravity observations /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/11025.

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41

Grant, Hazel Christine. "The role of Weddell Sea deep and bottom waters in ventilating the deep ocean." Thesis, University of East Anglia, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492970.

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42

Howe, John Alexander. "Bottom currents, contourites and related sedimentation in the Northern Rockall Trough, North Atlantic Ocean." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261216.

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43

Zheng, York Yao. "Time-lapse seismic imaging using elastic full waveform inversion of ocean-bottom cable data." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648657.

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44

Turgeon, Jocelyn. "An analysis of hull damage without fracture in single-bottom transversally framed ships subjected to grounding." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/38095.

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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1995, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1995.
by Jocelyn S.J. Turgeon.
M.S.

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45

Poropat, Lea [Verfasser]. "Importance of numerical ocean modelling and in situ ocean bottom pressure observations for satellite gravimetry from GRACE and GRACE-FO / Lea Poropat." Berlin : Freie Universität Berlin, 2020. http://d-nb.info/1215571895/34.

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46

Rajan, Subramaniam D. "An inverse method for obtaining the attenuation profile and small variations in the sound speed and density profiles of the ocean bottom." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15132.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1985.
MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.
Includes bibliographies.
by Subramaniam D. Rajan.
Ph.D.

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47

Dande, Suresh. "ESTIMATION OF DOWN-DIP LIMIT OF THE TONGA SEISMOGENIC ZONE FROM OCEAN BOTTOM SEISMOGRAPH DATA." OpenSIUC, 2013. https://opensiuc.lib.siu.edu/theses/1239.

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The largest earthquakes occur along the subduction thrust interface known as the seismogenic zone. Until recently, erosive margins like Tonga and Honshu have been thought to be unable to support earthquakes with magnitudes higher than 8.5. However, Mw 9, 2011 Tohoku-oki earthquake in Honshu requires a reevaluation of this notion. The seismic potential of Tonga is likely affected by the vertical spatial extent of the up-dip and down-dip limits, which confines the seismogenic zone. The larger the area of the seismogenic zone, the higher the potential for larger earthquakes. Some models suggest that down-dip limit coincides with the fore-arc Moho while others suggest that they are coincident with thermally controlled mineralogical phase changes during slab descent. Tonga is an ideal place to discriminate between these possibilities, as the incoming Pacific plate is cold and thick with rapid convergence, extending cool isotherms deep into the system. In contrast, the fore-arc Moho is only ~16 km deep. This study tests the hypothesis that the down-dip limit of the Tonga seismogenic zone coincides with the fore-arc Moho and thus ceases the seismicity by initiating a stable sliding between the mantle and the subducting crust. We determine the depth of the down-dip limit in Tonga by mapping the distribution of earthquakes recorded for a six-month period from January 1, 2010 to June 30, 2010 by a deployment of ocean bottom seismographs above the Tonga subduction zone. The earthquakes are located by a combination of grid-search method and least-square inversion of the observed arrival times. We identified a down-dip limit at a minimum depth of about 40 km below the sea level suggesting that the hypothesis is failed. Therefore, the commonly held idea that down-dip limit is coincides with the fore-arc Moho is not true in the Tonga case. It is likely controlled by the degree of serpentinization in the mantle wedge controlling the transition from stick-slip to stable sliding.

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48

Dolman, Richard. "Physical properties derived from seismic modelling at the toe of the Barbados accretionary complex." Thesis, University of Birmingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364522.

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49

Kim, Jong Rok. "Comparison of sound pressure in a wedge-shaped ocean as predicted by an image method and a PE model." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA234191.

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Thesis (M.S. in Engineering Acoustics)--Naval Postgraduate School, December 1990.
Thesis Advisor(s): Coppens, Alan B. ; Sanders, James V. "December 1990." Description based on title screen as viewed on March 31, 2010. DTIC Identifier(s): Sound Pressure, Sound Transmission, Transmission Loss, Parabolic Equation Models, Computerized Simulation, Underwater Acoustics, Acoustic Velocity, Ocean Bottom, Ocean Models, Theses. Author(s) subject terms: Image Method, Parabolic Equation Model, Wedge-shaped Ocean. Includes bibliographical references (p. 37). Also available in print.

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50

Williams, Sally Jayne. "Wave-seabed interaction in a stratified coastal environment." Thesis, The University of Sydney, 2010. https://hdl.handle.net/2123/28910.

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The attenuation of non—breaking waves in shallow waters can be dominated by soft seabed effects as opposed to water viscosity. Due to the complexity of natural systems, rheological approaches can provide useful parameter constraints on natural behaviours. In part I of this thesis a layered rheological model of the seabed is adopted. The upper part of the seabed is considered to be in a state of dynamic liquefaction, whilst the lower portion of the bed is more consolidated. It is demonstrated that in the absence of wave-induced turbulence the magnitude of the surface wave damping due to the presence of the porous bed is greater than that due to shear at the interface between the two fluids. For the case of a shallow layer of fluidised bed material, it is shown that the maximum damping effect of the porous elastic bed coincides with the maximum damping rates due to boundary layer shear effects, thus accentuating wave damping when the dimensionless lower layer depth is approximately 30—50% greater than the non—dimensionalised boundary—layer thickness. In part II of this thesis a model for the interaction between interfacial waves with the seabed is considered. A new wave dispersion equation is derived for waves on a two-layer stratification above a porous seabed including free surface effects. Numerical results indicate that the wavelength and wave amplitude are attenuated faster by a coarse seabed material as opposed to a fine sandy bed. It is shown that the profile of an interfacial wave exhibits properties similar to that of an interfacial wave propagating above a rigid bed and agrees qualitatively with observations of interfacial waves in littoral waters. The effect of a porous elastic bed is to increase the wave steepness, causing a narrower crest and a Wider trough. Comparison of the numerical results with experimental results on the different mechanisms for interfacial wave decay show that, in water of intermediate depth, the energy attenuation caused by a coarse—grained sandy seabed is greater than that due to bottom boundary layer damping, interfacial wave shear or interior Viscous damping.

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