Yes everything is engineered for quakes but as with everything it depends on the size of quake and it's location / depth, duration aftershocks and how the land reacts.
Seeing pictures whole mountainsides clog river valleys in steep terrain is not regular and not many quakes over 6 with records showing local damage as simply no one has records in remote areas.
I agree that it is not uncommon for smaller quakes at a much larger distance as a generilisation but scale and locality of quake and resilience of assets are all factors with lots of unknowns .
Very happy to read that the core equipment at Hides is reported as undamaged but it is not a clear bill of health and is a initial summary. I wonder how much luck is involved and how much over engineering as I am not sure what factor they were built to with what expectation of what size quakes?
To put it in perspective ( it is very uncommon in this area at this magnitude) this is a great site from which you can filter and show current and aftershocks, new quakes and also look historically at size and distance of quakes. Great visual representation.