Best answer on the thread so far.
Bad location and bad logistics.
There are two interesting comparisons to be made, Charlevoix (1663) and Lisbon (1755).
In the case of Lisbon, a terrible tidal wave wiped out the entire capital city of the Portuguese Empire. People were horrified to find out that prominent, religious and charitable people were wiped out, yet whore houses (which tended to be in the cheaper, uphill regions) were spared. It seemed like God’s justice had been inverted.
In the case of Charlevoix, the resident population of Quebec was socially dominated by fur trappers, etc., who were men without wives. The City of Quebec became known fro drunkenness, prostitution, etc. One February, a nun claimed to have a terrifying vision of destruction of the city with mountains tossed into the sea. She called the city to repentance, and, amazingly, it worked! The city prohibited drunkenness, cracked down on prostitution. Johns and Pimps wore sack-cloths in the streets. Daily prayer vigils lined the streets.
A terrifying earthquake did erupt, the worst ever recorded in North America, east of the Rockies. Steeples in Mass Bay colony collapsed; church bells were rung by the sway in South Carolina. Entire mountainsides did in fact slip into the St. Lawrence. But no-one in Quebec City, right near the epicenter was harmed.
(After learning about the Charlovoix Earthquake of 1662 from the convent where the nun had lived, I found out that despite the massive destruction, scientists had doubted it was a major earthquake. I poked around wondering how this was possible. Eventually, geologists re-examined the evidence and upgraded the earthquake from a VII to a X on the Mercalli Intensity Scale. That’s like a factor of 1,000!)