Is it allowed to operate the 2-axis sensor (+/-2g) in a x-y plain, where in
z-direction a high static
acceleration (100g) is present?
No damage will be caused to the accelerometer
The datasheet (Absolute maximum ratings) says +-500g - with no damage
due to cross-axis response the x- and y-axes will likely saturate. It is highly
unlikely that the 100g acceleration will be exactly and solely along the
z-axis. 2g is only 2% of the 100g, so it won’t take much misalignment to
saturate the x/y.
This means it would not destroy the part but is unlikely that you will get good
data out of the X and y axis (if any)