A study of the seismic structure of upper oceanic crust using wide-angle reflections
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution January 1983 The lateral homogeneity of oceanic crust on the scale of a seismic experiment is a condition that most me...
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Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
1983
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ftwhoas:oai:darchive.mblwhoilibrary.org:1912/2588 2023-05-15T17:32:36+02:00 A study of the seismic structure of upper oceanic crust using wide-angle reflections Rohr, Kristin Marie Michener Western North Atlantic Ocean 1983-01 application/pdf https://hdl.handle.net/1912/2588 en_US eng Massachusetts Institute of Technology and Woods Hole Oceanographic Institution WHOI Theses https://hdl.handle.net/1912/2588 doi:10.1575/1912/2588 doi:10.1575/1912/2588 Ocean bottom Marine geophysics Knorr (Ship : 1970-) Cruise KN92 Thesis 1983 ftwhoas https://doi.org/10.1575/1912/2588 2022-05-28T22:57:40Z Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution January 1983 The lateral homogeneity of oceanic crust on the scale of a seismic experiment is a condition that most methods of seismic interpretation depend on. Whether this condition is in fact true is largely unknown and only recently have efforts been made to test this hypothesis. This thesis is part of that effort and is focussed on determining with as much resolution as possible the seismic structure of upper oceanic crust, i.e. Layer 1 and the uppermost part of Layer 2. This portion of the crust is of interest, because of the effect of the sediment-basement interface on the transmission and conversion of seismic energy, also because of the possibility of detecting lateral heterogeneities in upper Layer 2 caused by faulting, hydrothermal circulation etc. The data employed are a set of wide-angle reflections from oceanic crust 130 m.y. old in the western North Atlantic Ocean southwest of Bermuda. First, the sedimentary structure is determined by stacking the data along hyperbolae and interpreting the stacking velocities and two-way normal incidence travel-times for interval velocities. This method has not been applied to deep sea marine data before; it gives a more detailed velocity structure of the sediments than does a traditional study of the basement reflections' travel-times. Second, the same data are mapped into tau-p space in order to measure the velocity gradient in oceanic basement; unfortunately the scatter in the tau-p picks caused by the topography of the basement reflector combine with the properties of the tau-sum inversion to make such a measurement impossible. Third, the amplitudes of the basement reflections observed on three seismic lines are modelled by synthetic seismograms; each can be matched by velocity-depth models which contain a transition zone between the sediments and the basement. The different ... Thesis North Atlantic Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) Woods Hole, MA |
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Open Polar |
collection |
Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) |
op_collection_id |
ftwhoas |
language |
English |
topic |
Ocean bottom Marine geophysics Knorr (Ship : 1970-) Cruise KN92 |
spellingShingle |
Ocean bottom Marine geophysics Knorr (Ship : 1970-) Cruise KN92 Rohr, Kristin Marie Michener A study of the seismic structure of upper oceanic crust using wide-angle reflections |
topic_facet |
Ocean bottom Marine geophysics Knorr (Ship : 1970-) Cruise KN92 |
description |
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution January 1983 The lateral homogeneity of oceanic crust on the scale of a seismic experiment is a condition that most methods of seismic interpretation depend on. Whether this condition is in fact true is largely unknown and only recently have efforts been made to test this hypothesis. This thesis is part of that effort and is focussed on determining with as much resolution as possible the seismic structure of upper oceanic crust, i.e. Layer 1 and the uppermost part of Layer 2. This portion of the crust is of interest, because of the effect of the sediment-basement interface on the transmission and conversion of seismic energy, also because of the possibility of detecting lateral heterogeneities in upper Layer 2 caused by faulting, hydrothermal circulation etc. The data employed are a set of wide-angle reflections from oceanic crust 130 m.y. old in the western North Atlantic Ocean southwest of Bermuda. First, the sedimentary structure is determined by stacking the data along hyperbolae and interpreting the stacking velocities and two-way normal incidence travel-times for interval velocities. This method has not been applied to deep sea marine data before; it gives a more detailed velocity structure of the sediments than does a traditional study of the basement reflections' travel-times. Second, the same data are mapped into tau-p space in order to measure the velocity gradient in oceanic basement; unfortunately the scatter in the tau-p picks caused by the topography of the basement reflector combine with the properties of the tau-sum inversion to make such a measurement impossible. Third, the amplitudes of the basement reflections observed on three seismic lines are modelled by synthetic seismograms; each can be matched by velocity-depth models which contain a transition zone between the sediments and the basement. The different ... |
format |
Thesis |
author |
Rohr, Kristin Marie Michener |
author_facet |
Rohr, Kristin Marie Michener |
author_sort |
Rohr, Kristin Marie Michener |
title |
A study of the seismic structure of upper oceanic crust using wide-angle reflections |
title_short |
A study of the seismic structure of upper oceanic crust using wide-angle reflections |
title_full |
A study of the seismic structure of upper oceanic crust using wide-angle reflections |
title_fullStr |
A study of the seismic structure of upper oceanic crust using wide-angle reflections |
title_full_unstemmed |
A study of the seismic structure of upper oceanic crust using wide-angle reflections |
title_sort |
study of the seismic structure of upper oceanic crust using wide-angle reflections |
publisher |
Massachusetts Institute of Technology and Woods Hole Oceanographic Institution |
publishDate |
1983 |
url |
https://hdl.handle.net/1912/2588 |
op_coverage |
Western North Atlantic Ocean |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
doi:10.1575/1912/2588 |
op_relation |
WHOI Theses https://hdl.handle.net/1912/2588 doi:10.1575/1912/2588 |
op_doi |
https://doi.org/10.1575/1912/2588 |
op_publisher_place |
Woods Hole, MA |
_version_ |
1766130803626999808 |