Imaging of one S-1 burst takes less than 3 seconds so it is indeed fortuitous ...I think this is an example of "the law of large number of calving fronts" in action.
Incidentally the same S-1 scene has further examples of this, the attached image is a couple of calving fronts towards the north and the lower arrow indicates another set of concentric waves, and the top arrow points to a semi-circular feature in the sea ice that looks like concentric waves from a recent calving have broken/disturbed the sea-ice.