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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Crust and upper mantle structure of the northeastern United States

Taylor, Steven Renold January 1980 (has links)
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1980. / Microfiche copy available in Archives and Science. / Vita. / Bibliography: leaves 226-239. / by Steven R. Taylor. / Ph.D.
102

Source, scattering and attenuation effects on high frequency seismic waves.

Chouet, Bernard January 1976 (has links)
Thesis. 1976. Ph.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences. / Microfiche copy available in Archives and Science. / Bibliography: leaves 174-183. / Ph.D.
103

The structure of the earth's mantle from body wave observations.

Sen Gupta, Mrinal Kanti January 1975 (has links)
Thesis. 1975. Sc.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences. / Vita. / Bibliography: leaves 358-387. / Sc.D.
104

Simultaneous inversion of surface wave phase velocity and attenuation for continental and oceanic paths.

Lee, Wook Bae January 1978 (has links)
Thesis. 1978. Ph.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences. / Microfiche copy available in Archives and Science. / Bibliography : leaves 241-256. / Ph.D.
105

Three-dimensional structure of the crust and mantle beneath the island of Hawaii.

Ellsworth, William Leslie January 1978 (has links)
Thesis. 1978. Ph.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences. / Microfiche copy available in Archives and Science. / Vita. / Bibliography : leaves 263-277. / Ph.D.
106

An investigation of body wave magnitude using the new digital seismic research observatories plus conventional catalogue data

Johnston, Janet Catherine January 1979 (has links)
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Science, 1979. / Bibliography: leaves 42-48. / by Janet Catherine Johnston Pruszenski. / M.S.
107

Mobile source development for seismic-sonar based landmine detection

MacLean, Douglas J. 06 1900 (has links)
Approved for public release, distribution is unlimited / Landmines continue to be a threat to both military and civilian communities throughout the world. Current methods of detection, while better than nothing, could certainly be improved. Seismic SONAR is a promising new technology that may help save countless lives. The goal of this thesis was to advance Seismic SONAR development by introducing a mobile source which could be easily used in practical applications. A small tracked vehicle with dual inertial mass shakers mounted on top was used for a source. The source accurately transmitted the shaker signal into the ground, and its mobility made it a practical choice for field operations. It excited Rayleigh waves, as desired, but also generated undesirable P-waves and was not found to be directional. It proved incapable of finding a target. Improvements, such as a deploying an array of mobile sources and a stronger source, should vastly enhance the performance of such tracked vehicles in seismic SONAR mine detection and should be pursued. / Ensign, United States Navy
108

Stochastic tomography and Gaussian beam depth migration

Hu, Chaoshun, 1976- 25 September 2012 (has links)
Ocean-bottom seismometers (OBS) allow wider angle recording and therefore, they have the potential to significantly enhance imaging of deep subsurface structures. Currently, conventional OBS data analysis still uses first arrival traveltime tomography and prestack Kirchhoff depth migration method. However, using first arrival traveltimes to build a velocity model has its limitations. In the Taiwan region, subduction and collision cause very complex subsurface structures and generate extensive basalt-like anomalies. Since the velocity beneath basalt-like anomalies is lower than that of high velocity anomalies, no first-arrival refractions for the target areas occur. Thus, conventional traveltime tomography is not accurate and amplitude constrained traveltime tomography can be dangerous. Here, a new first-arrival stochastic tomography method for automatic background velocity estimation is proposed. Our method uses the local beam semblance of each common-shot or common-receiver gathers instead of first-arrival picking. Both the ray parameter and traveltime information are utilized. The use of Very Fast Simulated Annealing (VFSA) method also allows for easier implementation of the uncertainty analysis. Synthetic and real data benchmark tests demonstrate that this new method is robust, efficient, and accurate. In addition, migrated images of low-fold data or data with limited observation geometry like OBS are often corrupted by migration aliasing. Incorporation of prestack instantaneous-slowness information into the imaging condition can significantly reduce migration artifacts and noise and improve the image quality in areas of poor illumination. Here I combine slowness information with Gaussian beam depth migration and implement a new slowness driven Gaussian beam prestack depth migration. The prestack instantaneous slowness information, denoted by ray parameter gathers p(x,t), is extracted from the original OBS or shot gathers using local slant stacking and subsequent localsemblance analysis. In migration, we propagate both the seismic energy and the principal instantaneous slowness information backward. At a specific image location, the beam summation is localized in the resolution-dependent Fresnel zone where the instantaneousslowness-information-related weights are used to control the beams. The effectiveness of the new method is illustrated using two synthetic data examples: a simple model and a more realistic complicated sub-basalt model. / text
109

P-wave velocity model for the southwest of the Yilgarn Craton, Western Australia and its relation to the local geology and seismicity /

Galybin, Konstantin A. January 2006 (has links)
Thesis (Ph.D.)--University of Western Australia, 2007.
110

Directional statistics, Bayesian methods of earthquake focal mechanism estimation, and their application to New Zealand seismicity data : a thesis submitted to the Victoria University of Wellington in fulfilment of the requirements for the degree of Master of Science in Statistics /

Walsh, David Leonard. January 2008 (has links)
Thesis (M.Sc.)--Victoria University of Wellington, 2008. / Includes bibliographical references.

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