On the subject of Progress Day...

Okay, so I just finished reading the story "Progress Day", and it's... it's amazing. It's beautifully written and gives a lot to speculate on. It also features Caitlyn (!!!).

However, as I was reading through it, there was something that confused me?? In the story, "Progress Day", there's a part where Tamara comments on the meaning of Progress Day for the two cities.

Above, Progress Day marks the moment the Sun Gates opened for the first time, allowing trade to pass easily between the east and west of Valoran. It also marks the moment when taxation on that trade turned the trickle of gold entering the city’s coffers into a fast flowing river. Below in Zaun, it is a day to remember those lost in the geological upheaval that created the east-west passage and submerged entire districts underwater.

The part about the "geological upheaval" in Zaun is... intriguing, and Tamara further elaborates on this later. Or so I think?? Because she is referring to a geological event that shook Zaun so I'm assuming she's talking about the same event she mentioned earlier.

The yawning chasm looks as though it ought to be ancient, the result of natural geological forces, but it came into existence within living memory and nothing natural created it. Man’s hubris and desire to master the elements wrought it. Tamara admires the strength of will it must have taken to enact a plan of such audacity that the splitting of the earth and the destruction of half of Zaun was seen as an acceptable price to pay for future prosperity.

Maybe I'm reading into this wrong, but it seems that Progress Day began to be celebrated in the two cities around the same time, and Zaun in particular begins to celebrate this holiday after a disaster that struck the city. However, in "The Weakest Heart", Camille speaks briefly on the Glorious Evolved celebrate Progress Day, saying,

The Glorious Evolved celebrated the old Zaunite tradition of sacrificing something personal for Progress Day in the hopes the next iteration of invention would be better. It was a practice that could be traced back to the old days of the city, when the people of Zaun had to face rebuilding their lives after the devastation of “the incident."

Camille, who is 80-90 years old, says that the tradition of sacrificing something personal for Progress Day, is an "old Zaunite tradition." However, this implies that Progress Day is an older holiday...??? The mention of an incident that devastated Zaun could perhaps be the geological upheaval that Tamara talks about in "Progress Day", unless Zaun had multiple destructive incidents???

It's just... I'm confused as to whether Progress Day is an older holiday that has been around for some time, or if it is a newer holiday, as in, within a lifespan, since Tamara does say that the chasm in which the College of Techmaturgy lies was created, "within living memory". Is the Camille we know a Camille that exists in the future...?

I probably missed something in the text or misinterpreted it so it would be very nice if someone could??? Clarify? thank