Is it true that saying "Allahu Akbar" during an earthquake is forbidden, or that it increases the severity of the calamity?

There is no evidence that takbir (saying "Allahu Akbar") increases the severity of an earthquake. Such a claim requires textual religious proof. It has not been authentically reported that the Prophet (peace be upon him) used to say takbir during earthquakes. Rather, he used to say: "O Allah, do not kill us with Your wrath, nor destroy us with Your punishment, and grant us well-being before that." Remembering Allah in any form is praiseworthy, but it is preferable to adhere to the dhikr (remembrances) that have been authentically reported.