Coseismic Deformation Detection and Quantification for Great Earthquakes Using Spaceborne Gravimetry
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Date
2012-03
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Ohio State University. Division of Geodetic Science
Abstract
Because of Earth’s elasticity and its viscoelasticity, earthquakes induce mass
redistributions in the crust and upper mantle, and consequently change Earth’s external
gravitational field. Data from Gravity Recovery And Climate Experiment (GRACE)
spaceborne gravimetry mission is able to detect the permanent gravitational and its
gradient changes caused by great earthquakes, and provides an independent and thus
valuable data type for earthquake studies. This study uses a spatiospectral localization
analysis employing the Slepian basis functions and shows that the method is novel and
efficient to represent and analyze regional signals, and particularly suitable for extracting
coseismic deformation signals from GRACE. For the first time, this study uses the Monte
Carlo optimization method (Simulated Annealing) for geophysical inversion to quantify
earthquake faulting parameters using GRACE detected gravitational changes. GRACE
monthly gravity field solutions have been analyzed for recent great earthquakes. For the
2004 Mw 9.2 Sumatra-Andaman and 2005 Nias earthquakes (Mw 8.6), it is shown for the
first time that refined deformation signals are detectable by processing the GRACE data
in terms of the full gravitational gradient tensor. The GRACE-inferred gravitational
gradients agree well with coseismic model predictions. Due to the characteristics of
gradient measurements, which have enhanced high-frequency contents, the GRACE
observations provide a more clear delineation of the fault lines, locate significant slips,
and better define the extent of the coseismic deformation; For the 2010 Mw 8.8 Maule
(Chile) earthquake and the 2011 Mw 9.0 Tohoku-Oki earthquake, by inverting the
GRACE detected gravity change signals, it is demonstrated that, complimentary to
classic teleseismic records and geodetic measurements, the coseismic gravitational
change observed by spaceborne gravimetry can be used to quantify large scale
deformations induced by great earthquakes.
Description
This Ohio State University Geodetic Science Report was prepared for, in part, and submitted to the Graduate School of the Ohio State University as a Dissertation in partial fulfillment of the requirements of the Doctor of Philosophy (PhD) degree.
This research is conducted under the supervision of Professor C.K. Shum, Division of Geodetic Science, School of Earth Sciences, The Ohio State University. The research results documented in this report resulted in a PhD Dissertation by Lei Wang (2012), Division of Geodetic Science, School of Earth Sciences, The Ohio State University. This research is partially funded by grants from NASA’s Interdisciplinary Science Program (NNG04GN19G), NASA’s Ocean Surface Topography Mission (OSTM) and Physical Oceanography Program (JPL1283230), the Air Force Materiel Command (FA8718-07-C-0021), and NSF’s Division of Earth Sciences (EAR-1013333). We would like to acknowledge Professor Frederik J. Simons, Department of Geosciences, Princeton University, for his hosting of Dr. Lei Wang for the summer visits.
This research is conducted under the supervision of Professor C.K. Shum, Division of Geodetic Science, School of Earth Sciences, The Ohio State University. The research results documented in this report resulted in a PhD Dissertation by Lei Wang (2012), Division of Geodetic Science, School of Earth Sciences, The Ohio State University. This research is partially funded by grants from NASA’s Interdisciplinary Science Program (NNG04GN19G), NASA’s Ocean Surface Topography Mission (OSTM) and Physical Oceanography Program (JPL1283230), the Air Force Materiel Command (FA8718-07-C-0021), and NSF’s Division of Earth Sciences (EAR-1013333). We would like to acknowledge Professor Frederik J. Simons, Department of Geosciences, Princeton University, for his hosting of Dr. Lei Wang for the summer visits.