The heaving of the earth described here is associated with earthquakes. In a myth recorded for the Chorti Maya, earthquakes are caused by the gods:
“Movements of the Chicchans within the hills cause earthquakes; a tremor indicates the Chicchan is turning in his sleep, and a violent earthquake ensues of the Chicchan turns completely over to like on his other side.” (J. Eric S. Thompson. Maya History and Religion. University of Oklahoma Press, Norman. 1976, p. 263).
In the Maya creation mythology, earthquakes figure prominently in the destruction of one of the world epics, a tradition continued through Aztec mythology (for the Maya area, see J. Eric S. Thompson. Maya History and Religion. University of Oklahoma Press, Norman p. 271, 332, and 345. 1976, p. 263. For the Aztec myth, the best source is “Leyenda de los Soles” Codice Chmalpopoca. Tr. Primo Feliciano Valazquez, UNAM, Mexico, 1975, p. 121).
The moving of the earth would be a tremendous portent, not to mention a terrifying physical experience.