The Compact Airborne Spectrographic Imager (CASI) and the satellite Moderate Resolution Imaging Spectroradiometer (MODIS) provide detailed information about the environment U.S. Naval forces choose to operate in. In recent years environmental conditions have been a driving factor in preventing the detection of underwater objects like mines. Suspended sediments are an environmental condition of interest. Remote sensors provide an opportunity to detect suspended sediments in a region prior to the commencement of operations and better prepare the force while reducing time required to complete operations. Monthly data sets collected using MODIS, from February 2005 to February 2006 show variations in weather patterns in the Mississippi Bight that cause the persistent presence of suspended sediments in certain areas of the Mississippi Bight. Major storm events such as hurricanes alter the location that suspended sediments persist in this region during the hurricane season. MODIS with 250m-pixel resolution is capable of detecting large-scale suspended sediment plumes while CASI with 1m-pixel resolution is capable of detecting very fine suspended sediment filaments as well as providing early warning of possible mine locations. As the mine warfare fleet diminishes in size, CASI and MODIS coupled with current sensors may provide an increase in detection capability while reducing the workload of mine detection ships. Continued research and study of suspended sediment transport during hurricane seasons may provide more information about how the environment changes.

The military threat of hostile submarines is increasing and the need for effective Anti-Submarine Warfare (ASW) operations is also increasing. In response, the ROK government and military have improved their ASW capabilities. In this thesis, the recommended track spacing for an Archimedes spiral search in a datum search problem was studied. To find a recommended track spacing, three analytical approaches were explored. Each of three analytical approaches has its own strengths and weaknesses. This analysis combined three analytical functions into a single parameterized expression. To find the best-fit parameters maximizing probability of detection, a simulation experiment with a NOLH (Nearly Orthogonal Latin Hypercube) design was used. / Korean Army author.

The work presented in this dissertation depicts past and present signatures of melt distribution at fast and intermediate spreading centers. The primary goal of the studies included in this thesis is to provide better understanding of melt distribution and variation in melt physical properties within and at the base of oceanic crust formed at these spreading centers. Furthermore, this work examines effects that melt presence might have on formation and structural characteristics of oceanic crust. To explore the above we use geophysical data collected during two expeditions conducted along the Juan de Fuca Ridge (intermediate) and the East Pacific Rise (fast). The major part of the thesis is based on the work conducted on high resolution reflection seismic data that investigate present day intracrustal melt distribution along the East Pacific Rise (EPR) axis extending between 8º20’ and 10º10’N. Here, the character of the melt reservoir is examined from different aspects and by using different seismic data analysis methods. By systematic analysis of the seismic reflection data, we show that the axial melt lens (AML) is segmented at different segment scales. Locations of the mapped disruptions in the AML correspond to previously identified tectonic discontinuities well expressed in the seafloor bathymetry. The above result corroborates genetic relationship between tectonic and magmatic segmentation. To examine melt distribution along the EPR, here for the first time we use amplitude variation with angle of incidence (AVA) crossplotting technique that was developed by oil and gas industry experts to look for presence of hydrocarbons. Further data examination for the first time for the mid-ocean ridges show presence of deeper lenses (lenses that are present below the AML). Presence of gaps in these sub-events and their collocation with what is believed to be the location of origin of the last documented eruption occurred in 2005-06, may shed light on the mechanisms behind the mid-ocean ridges volcanic processes. To explore variation in crustal structure and melt distribution at present day along the Juan de Fuca Ridge and relicts of past melt presence near ridge propagators wakes, a combination of gravity and multi-channel seismic data was used. Gravity modeling, constrained by seismic data, showed that robust topography (shallow axial depth and wide axial high) and thicker crust observed for the southern portion of this ridge system originate from enhanced melt supply at the base of the crust. In addition, prominent crustal thickening on the younger crust side of the inner propagators wakes (now on the ridge flanks) is brought into relationship with collocated frozen magma lenses imaged at the base of the crust. Spatial relationship of the two argues for their causal relationship at the time of the crustal formation on the axis. Our study suggests that these frozen lenses represent the record of once molten reservoir that most probably actively participated in the formation of the thicker crust.

Two thirds of the Earth's lithosphere is covered by the ocean. The oceanic lithosphere is formed at mid-ocean ridges, evolves and interacts with the overlying ocean for millions of years, and is eventually consumed at subduction zones. In this thesis, I use 2D and 3D multichannel seismic (MCS) data to investigate the accretionary and hydrothermal process on the ridge flank of the fast-spreading East Pacific Rise (EPR) at 9°37-40'N and the structure of the downgoing Juan de Fuca plate at the Cascadia subduction zone offshore Oregon and Washington. Using 3D multichannel seismic (MCS) data, I image a series of off-axis magma lenses (OAML) in the middle or lower crust, 2 -10 km from the ridge axis at EPR 9°37-40'N. The large OAMLs are associated with Moho travel time anomalies and local volcanic edifices above them, indicating off-axis magmatism contributes to crustal accretion though both intrusion and eruption (Chapter 1). To assess the effect of OAMLs on the upper crustal structure, I conduct 2-D travel time tomography on downward continued MCS data along two across-axis lines above a prominent OAML in our study area. I find higher upper crustal velocity in a region ~ 2 km wide above this OAML compared with the surrounding crust. I attribute these local anomalies to enhanced precipitation of alteration minerals in the pore space of upper crust associated with high-temperature off-axis hydrothermal circulation driven by the OAML (Chapter 2). At Cascadia, a young and hot end-member of the global subduction system, the state of hydration of the downgoing Juan de Fuca (JdF) plate is important to a number of subduction processes, yet is poorly known. As local zones of higher porosity and permeability, faults constitute primary conduits for seawater to enter the crust and potentially uppermost mantle. From pre-stack time migrated MCS images, I observe pervasive faulting in the sediment section up to 200 km from the deformation front. Yet faults with large throw and bright fault plane reflections that are developed under subduction bending are confined to a region 50-60 km wide offshore Oregon and less than ~45 km wide offshore Washington. Near the deformation front of Oregon margin, bending-related faults cut through the crust and extend to ~6-7 km in the mantle, whereas at Washington margin, faults are confined to upper and middle crust, indicating that Oregon margin has experienced more extensive bend faulting and related alteration. These observations argue against pervasive serpentinization in the slab mantle beneath Washington and suggest mechanisms other than dehydration embrittlement need to be considered to explain the intermediate depth earthquakes found along the Washington margin (Chapter 3). Using MCS images of a ~400 km along-strike profile ~10-15 km from the deformation front, I investigate the along-trench variation of the structure of downgoing JdF plate and its relation to the regional segmentation of Cascadia subduction zone. I observe that the propagator wakes within the oceanic plate are associated with anomalous basement topography and crustal reflectivity. Further landward, segment boundaries of ETS recurrence interval and relative timing align with the propagator traces within the subducting plate. I propose while the upper plate structure or composition may determine the threshold of fluid pore pressure at which ETS occur, the propagators may define barriers for ETS events that occur at the same time. I also observe a change in crustal structure near 45.8°N that is consistent with an increase in bend-faulting and hydration south of 45.8°N;. In addition, four previously mapped oblique strike-slip faults are associated with changes in Moho reflection, indicating that they transect the entire crust and may cause localized mantle hydration (Chapter 4).

Graduation date: 1967

In order to quantitatively examine the crustal structure of the Panama Basin without the benefit of local seismic refraction data, the following assumptions were made: (1) No significant lateral changes in density take place below a depth of 50 km. (2) The densities of the crustal layers are those of a 50-km standard section derived by averaging the results of 11 seismic refraction stations located in normal oceanic crust 10 to 40 million years (m. y. ) in age. (3) The density of the upper mantle is constant to a depth of SO km. (4) The thickness of the oceanic layer is normal in that region of the basin undergoing active spreading, exclusive of aseismic ridges. (5) The thickness of the transition layer is 1. 1 kin everywhere in the basin. Subject to these assumptions, the following conclusions are drawn from the available gravity, bathymetry, and sediment-thickness data: (1) Structurally, the aseismic ridges are surprisingly similar, characterized by a blocky, horst-like profile, an average depth of less than 2 km, an average depth to the Mohorovicic discontinuity of 17 km, and an average free-air anomaly of greater than +20 mgal. The fact that their associated free-air anomalies increase from near zero at their seaward ends to greater than +40 mgal at their landward ends suggests that the Cocos and Carnegie ridges are uplifted at their landward ends by lithospheric bending. (2) The centers of sea-floor spreading and fracture zones are characterized by a shoaling of the bottom and an apparent deepening of the Mohorovicic discontinuity. The only exception to this generalization is the northern end of the Panama fracture zone between the Cocos and Coiba ridges. (3) The Panama fracture zone and the fracture zone at 85°20'W longitude divide the Panama Basin into three provinces of different crustal thickness. Between these two fracture zones the crustal thickness is normal; west of 85°20W longitude it is greater than normal; and east of the Panama fracture zone it is less than normal. (4) In that part of the Panama Basin east of the Panama fracture zone there is a major discontinuity at 3°N latitude between a smooth, isostatically compensated crust to the south and an extremely rugged, uplifted crust to the north. An explanation for this discontinuity is the effect of the inflection in the shape of the continental margin at 3°N latitude on the eastward subductiori of the Nazca plate. / Graduation date: 1974

The Carnegie Ridge is a linear, aseismic, submarine ridge lying between the Galapagos Islands and the coast of South America. A 2300 meter deep saddle near 86°W. longitude divides the ridge into western and eastern segments. Surface ship, near bottom, and grain size studies from the saddle have been used to delineate the present geological environment and history of the ridge. Structurally the Carnegie Ridge is rather simple in profile, being bounded by east-west trending scarps which give the ridge a block-faulted appearance. Acoustic basement over the ridge appears smooth on reflection profiles and is composed of chert. The sedimentary sequence above the chert horizon contains a lower chalk unit overlain by calcareous ooze. Where erosion has exposed the chalk a karst-like micro-topography is present which is characterized by steep walled channels and cliffs and consolidated bed forms undergoing erosion and dissolution. The ridge crest has been stripped of almost its entire sediment cover. Thick sequences of sediment are found only in areas protected from north or south flowing bottom currents. Evidence of erosion is provided by extensive channeling on both the north and south flanks of the ridge. Near bottom observations in one channel on the north flank revealed a large field of sand dunes indicating northward, downslope sediment transport. These dunes are found on a manganese-encrusted chalk which floors the channel. Hydrographic data suggest that the northward flow across the ridge may be produced by the spillover of bottom water. Near bottom and surface ship observations are consistent with a southward sediment transport on the south flank of the ridge. The mechanism responsible for this southward flow remains unresolved. Current meters deployed on the north and south flanks recorded only low speed currents, opposite in direction to the inferred sediment transport. Apparently the bottom water flow responsible for erosion and sediment transport over the ridge is episodic in nature and was not recorded during the present survey. The grain size characteristics of surface sediments respond to the same processes which control sediment distribution. Where erosion is evident over the ridge crest, coarse lag deposits of foraminiferal sand are found. Apparently the erosion is most pronounced at the sill depth on the ridge since the sediments tend to become finer both upslope and downslope from that point. Three dominant modes are present in the sand fraction from the ridge. These modes record the initial input and fragmentation of foraminiferal tests. Continued fragmentation and dissolution of these tests creates a large number of finer modes. The age of true basaltic crust over the ridge is between 10 and 26 million years. This crust was probably created during a period of very slow spreading on the Galapagos Rift Zone during the Miocene. Unconformities on the ridge indicate that erosion dates only from the mid-Pliocene. The initiation of erosion was probably in response to further uplift of the ridge. This uplift may have been related to slight southward underthrusting along the north flank of the ridge. / Graduation date: 1975 / Best scan available for figures on p.67, 96. The original is a black and white photocopy.

Thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1983. / Grant provided by NASA under Grant NAG 6-9. Includes bibliographical references (p. 187-193).

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

Inaug.-diss.--Leipzig. / Lebenslauf. "Literaturverzeichnis": p. [132]-134.