Multiscale InSAR Time Series (MInTS) analysis of surface deformation

TLDR

Wavelet decomposition efficiently handles spatial covariances in repeat‑pass InSAR, while the time‑dependent parametrization captures both known and unknown deformation processes independent of SAR acquisition times. The study introduces a method for extracting spatially and temporally continuous ground deformation fields from InSAR data. The method employs a spatial wavelet decomposition and a general time‑parameterization, estimating line‑of‑sight deformation from unwrapped interferograms via cross‑validated, regularized least‑squares inversion, with model‑resolution‑based regularization to adapt to sparse versus dense SAR acquisitions, demonstrated on 92 ERS and Envisat interferograms spanning 16 years in Long Valley, CA. MInTS produces high‑spatial‑density deformation maps of the Long Valley region.

Abstract

We present a new approach to extracting spatially and temporally continuous ground deformation fields from interferometric synthetic aperture radar (InSAR) data. We focus on unwrapped interferograms from a single viewing geometry, estimating ground deformation along the line‐of‐sight. Our approach is based on a wavelet decomposition in space and a general parametrization in time. We refer to this approach as MInTS (Multiscale InSAR Time Series). The wavelet decomposition efficiently deals with commonly seen spatial covariances in repeat‐pass InSAR measurements, since the coefficients of the wavelets are essentially spatially uncorrelated. Our time‐dependent parametrization is capable of capturing both recognized and unrecognized processes, and is not arbitrarily tied to the times of the SAR acquisitions. We estimate deformation in the wavelet‐domain, using a cross‐validated, regularized least squares inversion. We include a model‐resolution‐based regularization, in order to more heavily damp the model during periods of sparse SAR acquisitions, compared to during times of dense acquisitions. To illustrate the application of MInTS, we consider a catalog of 92 ERS and Envisat interferograms, spanning 16 years, in the Long Valley caldera, CA, region. MInTS analysis captures the ground deformation with high spatial density over the Long Valley region.