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Using Earth Deformation Caused by Surface Mass Loading to Constrain the Elastic Structure of the Crust and Mantle


Martens, Hilary Rose (2016) Using Earth Deformation Caused by Surface Mass Loading to Constrain the Elastic Structure of the Crust and Mantle. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9N29TX7.


Surface mass loads come in many different varieties, including the oceans, atmosphere, rivers, lakes, glaciers, ice caps, and snow fields. The loads migrate over Earth's surface on time scales that range from less than a day to many thousand years. The weights of the shifting loads exert normal forces on Earth's surface. Since the Earth is not perfectly rigid, the applied pressure deforms the shape of the solid Earth in a manner controlled by the material properties of Earth's interior. One of the most prominent types of surface mass loading, ocean tidal loading (OTL), comes from the periodic rise and fall in sea-surface height due to the gravitational influence of celestial objects, such as the moon and sun. Depending on geographic location, the surface displacements induced by OTL typically range from millimeters to several centimeters in amplitude, which may be inferred from Global Navigation and Satellite System (GNSS) measurements with sub-millimeter precision. Spatiotemporal characteristics of observed OTL-induced surface displacements may therefore be exploited to probe Earth structure. In this thesis, I present descriptions of contemporary observational and modeling techniques used to explore Earth's deformation response to OTL and other varieties of surface mass loading. With the aim to extract information about Earth's density and elastic structure from observations of the response to OTL, I investigate the sensitivity of OTL-induced surface displacements to perturbations in the material structure. As a case study, I compute and compare the observed and predicted OTL-induced surface displacements for a network of GNSS receivers across South America. The residuals in three distinct and dominant tidal bands are sub-millimeter in amplitude, indicating that modern ocean-tide and elastic-Earth models well predict the observed displacement response in that region. Nevertheless, the sub-millimeter residuals exhibit regional spatial coherency that cannot be explained entirely by random observational uncertainties and that suggests deficiencies in the forward-model assumptions. In particular, the discrepancies may reveal sensitivities to deviations from spherically symmetric, non-rotating, elastic, and isotropic (SNREI) Earth structure due to the presence of the South American craton.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Earth deformation; ocean tidal loading; surface mass loading; time series analysis; GNSS data processing; load Green's functions; Love numbers; Earth structure; crust; mantle; South America; ocean tides; Earth tides; tide-generating potential
Degree Grantor:California Institute of Technology
Division:Geological and Planetary Sciences
Major Option:Geophysics
Minor Option:Planetary Sciences
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Simons, Mark
Thesis Committee:
  • Jackson, Jennifer M. (chair)
  • Simons, Mark
  • Gurnis, Michael C.
  • Tsai, Victor C.
Defense Date:8 March 2016
Funding AgencyGrant Number
NASA Earth and Space Science FellowshipNNX14AO04H
NSF Graduate Research FellowshipDGE-1144469
NSF Geophysics ProgramEAR-1417245
Record Number:CaltechTHESIS:04102016-211741759
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for ch. 6 adapted for ch. 7
Martens, Hilary Rose0000-0003-2860-9013
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9666
Deposited By: Hilary Martens
Deposited On:05 May 2016 00:09
Last Modified:04 Oct 2019 00:12

Thesis Files

PDF (Thesis Document) - Final Version
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[img] Archive (ZIP) (Ocean Tidal Loading Movies) - Supplemental Material
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