The shadowing on the craters caused by being near Tethys’ terminator throws their topography into sharp relief. The larger, southernmost of the two shows a more complex structure. Its central peak is probably the result of the surface reacting to the violent post-impact excavation of the crater. The northern crater doesn’t have a similar feature. The impact was likely too small to form a central peak, or the composition of the material in the immediate vicinity couldn’t support the formation of a central peak.
Image Credit: NASA