Different values from ascending and descending orbits

Microwave Toolbox Interferometry
#1

Dear colleagues,

I was wondering if one could share experience with calculated vertical displacements from unwrapped interferogram from ascending and descending orbits. For some points of interest located along a wide road the values I have are quite different - about 25mm from asc. orbit and 85mm from desc. orbit.
Am I wrong?

Thank you.

#2

One cannot retrieve vertical displacements from one orbit configuration only without making some assumptions, so it is possible that the assumptions were not correct. Note also that interferograms contain atmospheric artefacts that differ from pair to pair.

#3

@mengdahl you are right, but I didn’t expect so large differences.

#4

Can you first check that your assumptions were not incorrect? Perhaps the movement was not purely vertical or E-W or N-S…

#5

Hi @hriston_bg, Is that displacement triggered by earthquake?. Generally in this displacement is clearer that you see different results in asc and desc orbits, because depending if your data acquisition is East-West (desc) or West-east (asc) (not literally horizontal acquisition, the flight direction is different to the north, then it would be southeast-northwest in desc). So you displacement, for example is to the west and this is a subsidence, in the desc orbit you will see LOS displacement different than LOS displacement generated by asc orbit (this value will be less for compesation: movement- asc viewing direction), but for your vertical will be like @mengdahl wrote (asc and desc orbit combinated).

#6

@Simonst7 yes, it is from earthquake. your considerations are right, but i was surprised by such large differences. unfortunately i can not find any in-situ data.

#7

There are EQ experts on this forum - perhaps you should post the interferograms?

#8

my results concerning the phase are comparable to those reported here
https://www.emsc-csem.org/Files/news/Earthquakes_reports/Newsletter_15_2019_Albania_EQ.pdf
pages 37-39
my idea was to unwrap the phase and check areas close to the EQ event (3-5 kim)
so after processing i was struck with this problem.
in this source
https://www.emsc-csem.org/Files/news/Earthquakes_reports/Preliminary_Report_Albania_26112019.pdf

unfortunately the only sources that could help me for this EQ are the ones i posted above
page 9 it is reported that an uplift is registered, but the location of the GNSS station is not known so
no possibility to cross-ckeck