Whitebeard’s DF allowed him to create earthquakes. Whitebeard’s awakened ability allowed him to manipulate the air around him by punching it and creating air quakes, rather than punching the ground and directly causing an earthquake through the ground.
Whitebeard was known as “The Strongest Man in The World” prior to the Marineford war, given this title I think in his prime, being such a powerful man and and one of the oldest Yonko’s at the time, it would be disappointing if he didn’t awaken his fruit. Also, Sengoku stated that Whitebeard had the power to destroy the world. Whitebeard potentially could’ve had the power to create an “earth destroying earthquake”.
It doesn’t seem too unlikely due to the display of the Gura Gura no Mi we have seen so far. The main reason I think Whitebeard didn’t show his full potential was due to his illness, aging, etc.. or simply because he did not want to destroy the world lol.