Thesis (Ph. D.)--University of Hawaii at Manoa, 2000. / Includes bibliographical references (leaves 102-106). Also available on microfiche.

Thesis (M.S.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references (leaves 47-49). Also available by World Wide Web.

Thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2005. / Bibliography: p. 119-129.

Thesis (M.C.E.)--University of Delaware, 2008. / Principal faculty advisor: James T. Kirby, Dept. of Civil & Environmental Engineering. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 379-383). Available also in a digital version from Dissertation Abstracts.

Knowledge of water depth is a crucial for planning military amphibious operations. Bathymetry from remote sensing with multispectral or hyperspectral imagery provides an opportunity to acquire water depth data faster than traditional hydrographic survey methods without the need to deploy a hydrographic survey vessel. It also provides a means of collecting bathymetric data covertly. This research explores two techniques for deriving bathymetry and assesses them for use by those involved in providing support to military operations. To support this aim a fieldwork campaign was undertaken in May, 2000, in northern Queensland. The fieldwork collected various inherent and apparent water optical properties and was concurrent with airborne hyperspectral imagery collection, space-based multispectral imagery collection and a hydrographic survey. The water optical properties were used to characterise the water and to understand how they affect deriving bathymetry from imagery. The hydrographic data was used to assess the performance of the bathymetric techniques. Two methods for deriving bathymetry were trialled. One uses a ratio of subsurface irradiance reflectance at two wavelengths and then tunes the result with known water depths. The other inverts the radiative transfer equation utilising the optical properties of the water to derive water depth. Both techniques derived water depth down to approximately six to seven metres. At that point the Cowley Beach waters became optically deep. Sensitivity analysis of the inversion method found that it was most sensitive to errors in vertical attenuation Kd and to errors in transforming the imagery into subsurface irradiance reflectance, R(0-) units. Both techniques require a priori knowledge to derive depth and a more sophisticated approach would be required to determine water depth without prior knowledge of the area of interest. This research demonstrates that water depth can be accurately mapped with optical techniques in less than ideal optical conditions. It also demonstrates that the collection of inherent and apparent optical properties is important for validating remotely sensed imagery.

The overall objective of this study is to address questions concerning the long-term mechanical strength of the lithosphere across the equatorial margin of Brazil. The approach used in this study consists of calculating the frequency response function estimates, also called admittance, using gravity and bathymetry data. These experimental estimates are then compared to theoretical admittance curves for Airy and thin elastic plate models for which estimates on the flexural rigidity or, equivalently, effective elastic thickness may be made. Twelve profiles, each 256 km long, were extracted from gridded gravity and bathymetry data (data sources: project EQUANT, Defense Mapping Agency, National Geophysical Data Center files and GEOS 3/SEASAT altimeter data). Three profiles were specifically used for testing truncation errors introduced by four different data treatment procedures (before Fourier transforming the data) : detrending, applying 10% cosine tapering, mirror imaging and the use of the first derivatives. The method I adopted is similar to the one used by McNutt (1983) and consists of testing how reliably a given admittance estimate can be recovered as a function of the data treatment procedure. A "predicted" gravity anomaly was obtained by convolving each bathymetric profile with a theoretical admittance filter. The edges of this anomaly are then submitted to the same treatment as the corresponding bathymetric profile before Fourier transforming both profiles and calculating admittance. The stability of the long-wavelength admittance estimates, in the presence of noise, was also investigated by introducing Gaussian noise, in the range of -50 to +50 mGals, in the "predicted" gravity signal. The results indicate that relatively unbiased long-wavelength admittance estimates can be obtained by using the first derivative of the data sets. In addition, it is shown that the mirroring technique, used in previous admittance studies across Atlantic-type margins, leads to overestimated admittance values and, therefore, overestimated flexural rigidities. Neither the theoretical curves for the Airy model nor the plate flexure model can explain the experimental admittance estimates. Not only are the experimental admittance estimates higher than the predicted values but they also have a narrower peak than the theoretical curves. This raises the question of the applicability of highly simplified isostatic models for tectonic provinces such as Atlantic-type continental margins. The following reasons may explain the discrepancies between the experimental and theoretical admittance estimates: (1) The abrupt nature of the transition between oceanic and continental crust controlled by the Romanche Fracture Zone - Unlike the eastern North American continental margin which was formed as a result of extensive rifling and pulling apart, the obliquely-rifled equatorial margin of Brazil has undergone a complex tectonic evolutionary process, where additional components such as shear and right-lateral wrenching were present. Therefore, representing the margin as a thin homogeneous elastic plate might be reasonable when the transition is gradual (for which the uniform flexural rigidity assumption seems reasonable) but is probably not a good approximation when it is as abrupt as the equatorial margin of Brazil (2) Presence of subsurface loads - Previous studies have shown that estimates of the average flexural rigidity of continental lithosphere using the admittance approach are biased when subsurface loads are present. In principle, the proximity of the Romanche Fracture Zone and associated volcanism suggest that shallow buried loads, caused by intrusive bodies, might be present in the area. This could partially account for the mismatch between theoretical curves and experimental admittance estimates. (3) "Masked" estimates - The admittance estimates presented here are likely to reflect the combination of two different signals: one related to the compensation of the Barreirinhas/Piaui-Camocim sub-basin which has no topographic/bathymetric expression and the other one related to the topography/bathymetry and its compensation which is of interest in the admittance studies. Since the wavelengths of these signals do not differ by much (around 80-100 km for the basin) it is possible that in the averaging process some overlapping occurs. The combination of these signals could yield anomalous results masking the admittance estimates in the diagnostic waveband. In addition, I present a two-dimensional cross section obtained by forward modelling the gravity anomaly along a profile using the line integral method. The uniform sedimentary infill of the Barreirinhas/Piaui-Camocim basin is enough to account for the gravity low over the inner shelf and no Moho topography is required. A plausible explanation for this "rootless" basin structure is that the lithosphere is capable of supporting the sediment infill load, and thus, has finite flexural rigidity (basin is locally uncompensated). / Graduation date: 1990

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: David R. Maidment. Vita. Includes bibliographical references. Also available from UMI.

Seafloor sedimentary depositional and erosional processes create a record of near and far-field climatic and tectonic signals adjacent to continental margins and within oceanic basins worldwide. In this dissertation I study both modern and paleo-seafloor surface processes at three separate and distinct study sites; Cascadia offshore Oregon, U.S.A., the Eastern North American Margin from south Georgia in the south to Massachusetts in the north, and the Deep Galicia Margin offshore Spain. I have the advantage of using modern geophysical methods and high power computing resources, however the study of seafloor processes at Columbia University's Lamont-Doherty Earth Observatory (LDEO) stretches back over ~80 yrs. Specifically I use data collected during a variety of geophysical research cruises spanning the past ~50 yrs.-the majority of which can be directly attributed to seagoing programs managed by LDEO. The modern seafloor is the integrated result of all previous near and far field processes. As such, I look below the seafloor using multi-channel seismic reflection data, which is the result of innumerable soundings stacked together to create an image of the sub-seafloor (paleo) horizons. I map, analyze and interpret the sub-seafloor sedimentary horizons using a variety of both novel and established methods. In turn, I use multi-beam sonar data, which is also the result of innumerable soundings to map, analyze, and interpret the modern seafloor topography (bathymetry). Additionally, I look to the results from academic ocean drilling programs, which can provide information on both the composition and physical properties of sediments. The sediment composition alone can provide important information about both near and far-field processes, however when supplemented with physical properties (e.g., density/porosity) the results become invaluable. In my second chapter, I use a compilation of multi-beam sonar bathymetry data to identify and evaluate 86 seafloor morphological features interpreted to represent large-scale erosional scours not previously recognized on the Astoria Fan offshore Oregon, U.S.A. The Astoria Fan is primarily composed of sediments transported from the margin to the deep ocean during Late Pleistocene interglacial periods. A significant portion of the sediments have been found to be associated with Late Pleistocene outburst flood events attributed to glacial lakes Bonneville and Missoula. The erosional scours provide a record of the flow path of the scouring event(s), which if well understood can provide important information for the study of past earthquakes as the sedimentary record remains intact outside of the erosional force created by the massive flood events. I design and implement a Monte Carlo inversion to calculate the event(s) flow path at each individual scour location, which results in a comprehensive map of Late Pleistocene erosion on the Astoria Fan. The results indicate that at least 4 outburst flood events are recorded by the scour marks. In my third chapter, I build a stratigraphic framework of the Eastern North American margin using a compilation of multi-channel seismic data. Horizon Au is a primary horizon within the stratigraphic framework and is thought to represent a significant margin wide bottom-water erosional event associated with subsidence of the Greenland-Scotland Ridge and opening of Fram Strait in the late Eocene/early Oligocene. A recent study found that the bottom-water was enriched in fossil carbon, leading us to hypothesize that the bottom-water erosion recorded by horizon Au may have been facilitated by chemical weathering of the carbonate sediments. I use sediment isopach(s) to build a margin-wide model of the late Eocene/early Oligocene continental margin in order to estimate the volume of sediments eroded/dissolved during the event marked by horizon Au. The results indicate that ~170,000 km3 of sediments were removed with a carbonate fraction of 42,500 km³, resulting in 1.15e18 mol CaCO₃ going into solution. An influx of this magnitude likely played a role in significant climatic changes identified at the Eocene-Oligocene transition (EOT). In my fourth chapter, I use a combination of 3D multi-channel seismic and multi-beam sonar bathymetry data collected during the Galicia 3D Seismic Experiment in 2013. The Galicia Bank is the largest of many crustal blocks and is located 120 km west of the coast on the Iberian Margin. The crustal blocks have been attributed to the opening of the North Atlantic Ocean in the Late Triassic/Middle Jurassic. The Galicia Bank is the source for the majority of sediments delivered to the Deep Galicia Margin, the focus of this study. I map the seafloor and 5 paleo-seafloor surfaces in order to study controls on sediment delivery provided by the crustal blocks. The results show that the crustal blocks begin as a barrier to and remain a primary control on sediment delivery pathways to the Deep Galicia basin. Additionally, the paleo-seafloor surfaces record morphological structures that can inform us on both near and far field past climatic and tectonic events e.g., the Alpine Orogeny and Pleistocene inter-glacial periods.

Thesis (Ph. D.)--Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Ocean Engineering; and the Woods Hole Oceanographic Institution), 2005. / Bibliography: p. 119-129. / Obtaining accurate and repeatable navigation for robotic vehicles in the deep ocean is difficult and consequently a limiting factor when constructing vehicle-based bathymetric maps. This thesis presents a methodology to produce self-consistent maps and simultaneously improve vehicle position estimation by exploiting accurate local navigation and utilizing terrain relative Measurements. It is common for errors in the vehicle position estimate to far exceed the errors associated with the acoustic range sensor. This disparity creates inconsistency when an area is imaged multiple times and causes artifacts that distort map integrity. Our technique utilizes small terrain "sub-maps" that can be pairwise registered and used to additionally constrain the vehicle position estimates in accordance with actual bottom topography. A delayed state Kalman filter is used to incorporate these sub-map registrations as relative position measurements between previously visited vehicle locations. The archiving of previous positions in a filter state vector allows for continual adjustment of the sub-map locations. The terrain registration is accomplished using a two dimensional correlation and a six degree of freedom point cloud alignment method tailored for bathymetric data. / (cont.) The complete bathymetric map is then created from the union of all sub-maps that have been aligned in a consistent manner. Experimental results from the fully automated processing of a multibeamn survey over the TAG hydrothermal structure at the Mid-Atlantic ridge are presented to validate the proposed method. / by Christopher N. Roman. / Ph.D.