a b s t r a c tWe propose a methodology using interferometric synthetic aperture radar (InSAR) time series analysis and a single GPS station to estimate the coseismic and postseismic crustal deformations in the Kanto region, Japan, which has been affected by the 2011 Tohoku earthquake. The proposed methodology depends on choosing a proper deformation trend(s) to accurately describe the earthquake deformation signature by studying the deformation time series of a single GPS station. The modeled deformation trend is subtracted from the unwrapped phase maps to separate the main deformation signature from the imposed errors. Some deformation components, not described by the model(s), will leak to the residual phase maps which will be subjected to temporal and spatial filtering. The final corrected unwrapped phase maps are estimated by restoring the modeled deformation trend to the filtered residual phase maps and finally the deformation time series is estimated using a least squares technique. The proposed methodology was designed to retrieve complex and fine surface deformations in areas that have been affected by large dominating deformation signatures and contain at a least single GPS station. The methodology was tested using Envisat-ASAR C-band images and validation was carried out using GPS stations resulting in a mean RMS error of 6.9 mm. The estimated deformation time series shows a differential postseismic deformation pattern that can be attributed to an off Boso peninsula motion triggered by the 2011 Tohoku earthquake.

In Japan, several cities endured severe damage due to soil liquefaction phenomenon, which was developed in association with the massive shaking of the 2011 Tohoku earthquake. Measuring soil liquefaction deformations was not an easy task, mainly because of the total loss of signal coherence in the affected regions. In this paper, we present our approach to estimate the deformations associated with soil liquefaction using interferometric synthetic aperture radar techniques. We use a stack of coseismic interferograms to identify the reliable pixels in the damaged areas using permanent scatterers technique. Then, we estimate and remove the preseismic mean velocity and DEM error components. Finally, we identify the liquefaction deformation component using least squares inversion and spatial phase filtering. We test the performance of the proposed approach using synthetic data, simulating the effects of soil liquefaction. The simulation results show a RMSE of the liquefaction deformation of 5.23 mm. After that, we estimate the deformation associated with soil liquefaction in Urayasu city, Japan, using ALOS-PALSAR data. The proposed approach allows a prompt estimation of the liquefaction deformation by utilizing the SAR images archives with only one postseismic SAR image.

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We investigated the post-seismic surface displacement of the 2011 Tohoku earthquake around the Kanto Plain (including the capital area of Japan), which is located approximately 400 km from the epicenter, using a global positioning system network during 2005-2015 and persistent scatterer interferometry of TerraSAR-X data from March 2011 to November 2012. Uniform uplift owing to viscoelastic relaxation and afterslip on the plain has been reported previously. In addition to the general trend, we identified areas where the surface displacement velocity was faster than the surrounding areas, as much as ~7 mm/year for 3 years after the earthquake and with a velocity decay over time. Local uplift areas were ~30 × 50 km 2 and showed a complex spatial distribution with an irregular shape. Based on an observed groundwater level increase, we deduce that the local ground uplift was induced by a permeability enhancement and a pore pressure increase in the aquifer system, which is attributable to mainshock vibration.

This paper presents new methodology for correcting interferometric synthetic aperture radar (InSAR) deformation maps using GPS observables and products. The methodology presents a sequential procedure for correcting the errors presented in InSAR deformation maps such as troposphere delay, ionosphere delay and baseline error. The main target of this research is to measure land deformations with geodetic accuracy using only one Lband interferogram with the aid of GPS observables and products. The proposed methodology was tested on Tokyo bay area which has been affected by the 2011 Tohoku earthquake. The results were verified against deformations detected by GPS stations and geodetic triangulation network showing a standard deviation of 5.6 and 10.5 millimeters, respectively.