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Total Variation Regularization of Geodetically Constrained Block Models in Southwest Taiwan
Author(s) -
Huang MongHan,
Evans Eileen L.
Publication year - 2019
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1029/2019jb018076
Subject(s) - geology , interferometric synthetic aperture radar , geodetic datum , geodesy , seismology , foothills , deformation monitoring , tide gauge , residual , thrust fault , slip (aerodynamics) , tectonics , deformation (meteorology) , synthetic aperture radar , sea level , remote sensing , algorithm , geography , cartography , physics , thermodynamics , oceanography , computer science
Abstract Rapid convergence between the Eurasian plate and the Philippine Sea Plate makes Taiwan one of the most active tectonic regions in the world, and this strain is accommodated on a complex network of thrust and strike‐slip faulting. Here, we use ascending and descending Interferometric Synthetic Aperture Radar (InSAR) data integrated with continuous GPS measurements to monitor interseismic deformation in southwest Taiwan. Geodetic observations show rapid (20–40 mm/year) southwestward motion in the Pingtung plain in south Taiwan and more than 10 mm/year uplift in the southern part of the Western Foothills. We use combined InSAR and CGPS measurements from 2004 to 2010 to constrain a block model of horizontal interseismic crustal deformation. Total variation regularization (TVR) serves as a tool for block model selection to algorithmically assess the block model geometry based on geodetic observations, simultaneously estimating block rotations and fault slip rates on block‐bounding faults. The block model results suggest that the margins of the Western Foothills accommodate most of the interseismic deformation in southwestern Taiwan. Thirty‐five independent blocks are required to explain interseismic crustal deformation with a mean residual velocity of 3.6 mm/year. Based on this horizontal model, we then forward predict vertical displacement and find good consistency between the predicted uplift and the geodetic observations. Our approach shows an efficient and objective way to estimate fault activities and seismic hazards in the interseismic period based on dense geodetic measurements and their uncertainties.