Abnormal deformation(phase unwrap) By snaphu

[Ori3570]

Hi everyone
I used SNAP to obtain a deformation map(20220520~20220601).But I met a problem.

1）the deformaion map has some abnormal information, for example the subsidence part (red 0.017) appears to be too large compared to the uplift part (blue 0.757).
2）Why does the middle part look so complicated? Is this caused by snaphu or the terrain itself?

please ,can anybody help me?
Thank you sincerely

[ABraun]

@Ori3570

2）Why does the middle part look so complicated? Is this caused by snaphu or the terrain itself?

To answer this, it would be good to have a look at the interferogram.

[Ori3570]

It looks like this.

There seems to be a lot of noise in the middle part

[ABraun]

yes, these patterns are probably causing unwrapping errors. You might try different interferogram filter configurations, especially, the Sigma value of the Goldstein filter could be lowered to avoid artefacts in noisy areas.

[Ori3570]

Thank you. It’s a good solution to my problem. By the way, for my first question, through many experiments, I found that it was caused by many earthquakes in a short time

[EJFielding]

Yes, for large earthquakes, lower amounts of filtering often work better to reduce unwrapping errors.