The Charlevoix seismic zone lies northeast of Quebec City along the St. Lawrence River, and it is eastern Canada's most seismically active region -- five earthquakes of estimated magnitude 6 or greater have struck here since Europeans began keeping records. The reason is written deep in the bedrock. The Saint Lawrence rift system formed during the breakup of the supercontinent Rodinia in the late Neoproterozoic and early Paleozoic eras, leaving a network of faults running parallel to the river. Then, roughly 450 million years ago, a meteorite slammed into the region, creating the 54-kilometer-wide Charlevoix impact structure. Where the ancient rift faults intersect the weakened rock of the impact crater, stress concentrates and releases. Most earthquakes in the zone originate in the Grenvillian basement rock at depths between 7 and 15 kilometers. The 1663 event ruptured along a fault zone larger than the one that produced the famous 1812 New Madrid earthquake in the American Midwest.

The destruction was not measured in collapsed buildings -- there were few stone structures in New France to collapse. It was measured in landscape. Massive landslides swept down the banks of the Saint Lawrence, the Saint-Maurice, and the Batiscan Rivers, dumping so much sediment into the waterways that the St. Lawrence itself ran muddy for up to a month. Near Trois-Rivieres, several waterfalls were physically transformed by the volume of earth that slid into them. Underwater, the damage was equally dramatic. Modern multibeam bathymetry surveys of the Saguenay Fjord have identified a series of submarine landslide deposits on the fjord floor that scientists attribute to the 1663 earthquake. The Saguenay region sits within a geological graben -- a down-dropped block of the earth's crust -- that made its steep underwater slopes especially vulnerable. The shaking that lasted only minutes resculpted the submarine topography of an entire fjord.

The earthquake struck during the early European settlement of North America, and its best chroniclers were Catholic missionaries stationed in the wilderness. The Jesuits, Ursulines, and Augustinians all left written accounts. Among them, Father Jerome Lalemant stood out for his measured, relatively restrained descriptions of the devastation, which he sent back to his superiors in Europe. Other accounts were less restrained. Some missionaries attributed the earthquake to divine retaliation for the colonists' sins, particularly the sale of alcohol to Indigenous peoples. The timing seemed to confirm this interpretation: the earthquake struck on the last day of carnival, the evening before Mardi Gras, as if Providence itself had chosen the moment. Even six hundred kilometers away in Roxbury, Massachusetts, Reverend S. Danforth recorded the shaking at around 6 p.m. -- the chimneys on houses along Massachusetts Bay cracked, and pewter was thrown from shelves. Danforth's record, using the Julian calendar then in use in New England, dated the event to January 26.

When the shaking finally subsided and the missionaries confirmed that no lives had been lost, they pivoted from terror to theology. The earthquake was not a disaster but a warning -- and a sign of God's protection over the faithful of New France. Churches filled. Wine and brandy traders appeared to repent. The traffickers in alcohol who had drawn divine wrath went quiet, at least for a time. But the piety was short-lived. Within weeks the colonists drifted back to their old habits, and Father Lalemant and his fellow missionaries found themselves, as one record dryly notes, wishing for another great earthquake to help them in their cause. The land, meanwhile, continued to tremble. Aftershocks persisted for months. The Charlevoix seismic zone has never fully gone quiet -- it remains the most seismically active region in eastern Canada, a reminder that the forces unleashed on that February evening in 1663 are not a relic of the past but a permanent feature of the landscape.