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Contribution of Satellite Gravimetry to Understanding Seismic Source Processes of the 2011 Tohoku-Oki EarthquakeThe 2011 great Tohoku-Oki earthquake, apart from shaking the ground, perturbed the motions of satellites orbiting some hundreds km away above the ground, such as GRACE, due to coseismic change in the gravity field. Significant changes in inter-satellite distance were observed after the earthquake. These unconventional satellite measurements were inverted to examine the earthquake source processes from a radically different perspective that complements the analyses of seismic and geodetic ground recordings. We found the average slip located up-dip of the hypocenter but within the lower crust, as characterized by a limited range of bulk and shear moduli. The GRACE data constrained a group of earthquake source parameters that yield increasing dip (7-16 degrees plus or minus 2 degrees) and, simultaneously, decreasing moment magnitude (9.17-9.02 plus or minus 0.04) with increasing source depth (15-24 kilometers). The GRACE solution includes the cumulative moment released over a month and demonstrates a unique view of the long-wavelength gravimetric response to all mass redistribution processes associated with the dynamic rupture and short-term postseismic mechanisms to improve our understanding of the physics of megathrusts.
Document ID
20120011856
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Han, Shin-Chan (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Sauber, Jeanne (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Riva, Riccardo (Delft Univ. of Technology Delft, Netherlands)
Date Acquired
August 26, 2013
Publication Date
July 3, 2011
Publication Information
Publication: Geophysical Research Letters
Volume: 38
Subject Category
Geophysics
Report/Patent Number
GSFC.JA.01193.2012
Distribution Limits
Public
Copyright
Other