Abstract
ABSTRACTInterferometric synthetic aperture (InSAR) has been widely applied to natural disaster monitoring. However, it has limitations due to the influence of noise sources such as atmospheric and topographic artefacts, data processing errors, etc. In particular, atmospheric effect is one of the most prominent noise sources in InSAR for the monitoring of small magnitude deformations. In this paper, we proposed an efficient multi-temporal InSAR (MTInSAR) approach to measure small co-seismic deformations by minimizing atmospheric anomalies. This approach was applied to investigate the 18 September 2004 earthquake over Huntoon Valley, California, using 13 ascending and 22 descending ENVISAT synthetic aperture radar (SAR) images. The results showed that the co-seismic deformation was ±1.5 and ±1.0 cm in the horizontal and vertical directions, respectively. The earthquake source parameters were estimated using an elastic dislocation source from the ascending and descending acquisitions. The root mean square errors between the observed and modelled deformations were improved by the proposed MTInSAR approach to about 3.8 and 1.8 mm from about 4.0 and 5.2 mm in the ascending and descending orbits, respectively. It means that the MTInSAR approach presented herein remarkably improved the measurement performance of a small co-seismic deformation.
Highlights
Synthetic aperture radar (SAR) interferometry (InSAR) utilizes SAR images acquired at different times to measure surface deformation with an unprecedented spatial resolution (e.g. Massonnet & Feigl 1998; Lu 2007)
The results showed the following: (1) that the Centroid Moment Tensor (CMT) and California Integrated Seismic network (CISN) catalogues may not be accurate for source parameter estimation of small earthquakes, (2) that the NCAeqDD catalogue was the best choice among the three catalogues, and (3) that the multitemporal InSAR (MTInSAR) approach developed was much better than one interferogram approach for precise estimation of the source parameters
A MTInSAR approach was applied for the measurement of small co-seismic deformation fields with reduction of error sources such as atmospheric error, topographic artefacts, etc
Summary
Synthetic aperture radar (SAR) interferometry (InSAR) utilizes SAR images acquired at different times to measure surface deformation with an unprecedented spatial resolution (e.g. Massonnet & Feigl 1998; Lu 2007). Synthetic aperture radar (SAR) interferometry (InSAR) utilizes SAR images acquired at different times to measure surface deformation with an unprecedented spatial resolution Massonnet & Feigl 1998; Lu 2007). The InSAR technique can be used to derive the source parameters associated with seismic and volcanic processes, which has allowed for better investigation of the mechanisms of geologic activities Jung et al 2011; Zhao et al 2012; Deffontaines et al 2016). The InSAR technique based on a repeat-pass observation is faced with the limitation that the interferometric phase is delayed by atmospheric effects when the radar signals travel through the atmosphere (mainly troposphere and ionosphere). Localized phase changes due to small deformation can suffer from severe atmospheric artefacts.
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