you may have heard of the 1859 Seattle earthquake that caused much of the city to be rebuilt, but this is the first I've seen how... they leveled a LOT of hills, and used all that gravel to level the ground first, and it filled in a lot of canyons

Canals were dug, rivers were diverted and mountains were moved. In particular, the glacial hills and ridges which separated neighborhoods from the downtown waterfront were deemed a major impediment to travel and commerce, and a prime target for removal.

https://ritkanlathatotortenelem.blog.hu/2015/09/17/akik_hegyeket_mozgattak_meg
https://mashable.com/2015/08/18/building-seattle/