ERS 1 SAR precision images misplaced

Hi everybody,
I’ve downloaded 75 ERS Precision Image products collected in the first weeks of 1996 over the East Antarctic Plateau from ESA dissemination service. All underwent the same processing in SNAP (Orbit file>Calibration>multilooking>speckle filter>terrain correction). Considered the site and the small time span, they should match pretty fine over the respective overlapping areas. However they are all misaligned, often also images acquired consecutively.
Does anybody know if there is a special processing technique for ERS products or the poor georeferencing it is a common issue?
Is there a way to realign coherently the products? Unfortunately a S1 image cannot be used as a guide due to the drift of the ice sheet to the sea.

Any suggestion is appreciated,

The poor georeferencing causing issues with terrain correction is a known problem. Over land with stable terrain features the solution would be to use SAR simulation terrain correction that is based on a DEM. Over you test site this is probably not an option.

Instead of terrain correcting your images individually try to co-register them first and terrain correcting the resulting stack. You will need to interfere manually in the co-registration due to the said georeferencing issues. In case you want to do this coherently (for later InSAR use) you need to use the corresponding SLC-products.

Thanks for the suggestion, I’ll try try and, hopefully, update the topic.