2026-09-23T06:36:00Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/80592022-01-13T07:54:24Zcom_1721.1_7582com_1721.1_7581col_1721.1_131022
Robert D. van der Hilst.
Kárason, Hrafnkell, 1970-
Massachusetts Institute of Technology. Dept. of Earth, Atmospheric, and Planetary Sciences.
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
2005-08-24T20:00:44Z
2005-08-24T20:00:44Z
2002
2002
http://hdl.handle.net/1721.1/8059
51039003
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2002.
Includes bibliographical references (p. 205-224).
In this thesis I combine high resolution seismic tomography and realistic flow modeling to constrain mantle convection. The bulk of the data used in the tomographic imaging are millions of P, pP and pwP travel time residuals, read from high frequency seismic records. The distribution of earthquakes and stations results in uneven data coverage and to improve the model I use core phases (PKP, Pdiff) for the deep mantle and surface reflected phases (PP) for the shallow mantle. Since narrow rays are not adequate for low frequency measurements, I construct broad 3-D sensitivity kernels to relate some of the added data to earth's structure. Furthermore, the parameterization of the tomographic model is adapted to data density and the model shows, among other details, the varying style of subduction in the shallow mantle and complex flow patterns around the transition zone between the upper and lower mantle. I develop a novel and efficient method of modeling buoyancy driven mantle flow in spherical geometry. Here, the linear Stokes equation is solved using a Green's function approach and 3-D surfaces, representing the boundaries of dense material, such as subducting slabs, are tracked through time.
by Hrafnkell Kárason.
(cont.) I describe the basis of the approach, represent tests, and investigate the thickening and slowing of subducting slabs for different viscosity contrasts between the upper and lower mantle. I compare seismic tomography, flow modeling and reconstructed plate motions associated with the collision of India to mainland Asia, in particular, the south and south-west motion of the Sunda block. This way I can evaluate subduction scenarios and make quantitative comparison between tomography and plate reconstructions. I conclude that a viscosity increase of -200 in the lower mantle, resulting in -10 times higher viscosity than previously estimated, best fits the observations. Juxtaposing the tomography, the flow models and inversion tests using the flow models as input, indicates that the results are robust.
Ph.D.
228 p.
20542940 bytes
20542698 bytes
application/pdf
application/pdf
eng
Massachusetts Institute of Technology
M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.
http://dspace.mit.edu/handle/1721.1/7582
Earth, Atmospheric, and Planetary Sciences.
Constraints on mantle convection from seismic tomography and flow modeling
Thesis
application/pdf
false
Publication
unknown
unknown
<Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="7e0fb145-5375-40f9-a551-a649fd2f4aa6">
<Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type>
<Language>eng</Language>
<Title>Constraints on mantle convection from seismic tomography and flow modeling</Title>
<PublishedIn>
<Publication>
</Publication>
</PublishedIn>
<PublicationDate>2002</PublicationDate>
<Authors>
<Author>
<DisplayName>Kárason, Hrafnkell, 1970-</DisplayName>
<Affiliation>
<OrgUnit>
</OrgUnit>
</Affiliation>
</Author>
</Authors>
<Editors>
</Editors>
<Publishers>
<Publisher>
<DisplayName>Massachusetts Institute of Technology</DisplayName>
<OrgUnit />
</Publisher>
</Publishers>
<License>http://dspace.mit.edu/handle/1721.1/7582</License>
<Keyword>Earth, Atmospheric, and Planetary Sciences.</Keyword>
<Abstract>In this thesis I combine high resolution seismic tomography and realistic flow modeling to constrain mantle convection. The bulk of the data used in the tomographic imaging are millions of P, pP and pwP travel time residuals, read from high frequency seismic records. The distribution of earthquakes and stations results in uneven data coverage and to improve the model I use core phases (PKP, Pdiff) for the deep mantle and surface reflected phases (PP) for the shallow mantle. Since narrow rays are not adequate for low frequency measurements, I construct broad 3-D sensitivity kernels to relate some of the added data to earth's structure. Furthermore, the parameterization of the tomographic model is adapted to data density and the model shows, among other details, the varying style of subduction in the shallow mantle and complex flow patterns around the transition zone between the upper and lower mantle. I develop a novel and efficient method of modeling buoyancy driven mantle flow in spherical geometry. Here, the linear Stokes equation is solved using a Green's function approach and 3-D surfaces, representing the boundaries of dense material, such as subducting slabs, are tracked through time.</Abstract>
<Access xmlns="http://purl.org/coar/access_right"
>
</Access>
</Publication>