9/11 was meant to be dramatic, but not too dramatic, so it wouldn’t arouse any suspicion that conflicts with their narrative. They wanted the buildings to fall, but needed to ensure other structures around the World Trade Centers would not be damaged. Earthquakes are rare, but they do happen in New York City. There was a 2.4 that hit the north side of Manhattan Island earlier that year on January 17. So the structures in that area are designed to withstand 4.0-4.5 earthquakes.
The largest earthquake in New York City was a 5.0-magnitude in August 1884. Centered off Queens’ Rockaway Beach and according to reports “opened crevices near the Brooklyn reservoir, rocked the Brooklyn Bridge and knocked down chimneys and cracking walls as far away as Pennsylvania.” So the largest one ever recorded in New York City made a crack in a lake and made a bridge built in the 1869 sway a little bit.