measuring interseismic deformation using InSAR 1

Long time no see. I just passed the qualify exam and I am on my second half journey to a PhD.

Today I am going to discuss existing technique and approaches to measure interseismic deformation using InSAR. This is an interesting topic. Currently several groups of people are working on InSAR time-series techniques. In US these groups includes Stanford, Caltech, JPL, Scripps, Berkeley, UCR, etc etc...

Let's start from Persistent Scatterers InSAR (PS). This technique is first developed by [Ferretti et al]. It works like this: align a stack of the SLC images; scale the amplitude image; compute the pixel-wise mean amplitude (m) and standard deviation of the amplitude (σ) for a whole stack; compute the D = σ/m; treat the pixel where D is smaller than a threshold as Permanent Scatters; model the phase of each PS as a mix of linear deformation and DEM error and solve a least-square problem to retrieve both the DEM error and a linear deformation rate.

Instead of using a threshold of amplitude dispersion, Lyons and Sandwell compute s = m/σ and weight the real and imaginary part of the complex image by s^2; apply a non-isotropic filter and form interferogram.

Instead of amplitude dispersion, stanford group [Hooper et al] include the phase information to identify PS. Their method is written in JGR paper. I haven't understood this method yet.