Consider the fact that Island 1 is much larger than City 7 and that explosive decompression would occur in a confined pressurized place.
The hole would cause decompression to be sure, but with a ceiling of 2000m there is a LOT of atmosphere to evacuate as opposed to a small compartment aboard, say a Uraga class carrier. The damage would need to be sealed as soon as possible, but it wouldn't necessarily drain the whole dome immediately.