Sketch (not to scale) of the three possible sources for star-formation induced shocks in the GMCs within the NGC 253 CMZ. We illustrate these three sources of shocks described in Sect. 5.3, and the relative layout of two possible line-of-sight (L.O.S.) orientations relative to the layout of shocked gas in each GMC. We assume the size of individual GMCs is comparable or larger than the ALCHEMI beam pc. The shocks probed by HNCO and SiO can be either approximated as (a) centralized mini-starburst episodes, labels in black, with the yellow star at center and the associated outflow in pale green), (b) sporadic/fragmented turbulent shock events that are scattered both temporally and spatially throughout the GMC (label in purple, with green and red asterisks), and (c) the cloud-cloud collision leading to shock episodes (label in orange).