Is the narration valid which states that the Earth rests on the back of a bull, and that the bull's movement of its head causes earthquakes, and was this mentioned in Tafsir Ibn Kathir?

It has not been proven that the Earth rests on the back of a whale, neither by evidence from the Qur'an nor from sound Sunnah (definition). What has been narrated in this regard are merely reports from some Companions and Successors, and their source might be Ka'b al-Ahbar or the books of the Children of Israel. There are also مرفوعة (marfu'ah) hadiths mentioned concerning this matter, but they are weak and fabricated. Therefore, one must refrain from asserting such matters with certainty and entrust their knowledge to Allah the Almighty, as the Prophet, peace and blessings be upon him, said: "Do not believe the People of the Book, nor disbelieve them, but say: 'We believe in Allah and what has been revealed to us.'"