Theophanes described two earthquakes that occurred about three years apart and a third earthquake around 756/757 CE, treated separately as the By No Means Mild Quake. The year he assigned to the first of the two earlier earthquakes (the Holy Desert Quake) conflicts with archaeoseismic evidence from Bet She’an, which provides a terminus post quem of 749 CE for that event, which struck the Jordan Valley and the Sea of Galilee. To avoid chronological confusion, these earthquakes are referred to by name rather than date.

The Holy Desert Earthquake is said to have struck first at 10 a.m. on 18 January, though this time and date more likely refer to when the subsequent Talking Mule Quake occurred. The Holy Desert Quake was described as a great earthquake in Palestine, by the Jordan and in all of Syria where numberless multitudes perished and churches and monasteries collapsed, especially those in the desert of the Holy City [Jerusalem].

The Talking Mule Quake is said to have struck Syria in the same year (A.M.a 6241, 25 Mar 748 – 24 Mar 749 CE) that Leo the Khazar was born to Constantine V. Theophanes reports that some cities were entirely destroyed, others partially so, while others slid down entire, with their walls and houses, from positions on mountains to low-lying plains, a distance of six miles or thereabout. The sliding village likely reflects an embellished account of a translational landslide, technically described as a block slide. Theophanes adds that eyewitnesses affirmed that the ground in Mesopotamia was split along two miles and that out of the chasm was thrown up a different soil, very white and sandy, in the midst of which there came up an animal like a mule, quite spotless, that spoke in a human voice and announced the incursion of a certain nation from the desert against the Arabs, which indeed came to pass. Despite the fantastical appearance of an oracular Talking Mule — which became a very popular part of the story — the accompanying details of an earth fissure and sand boils remain seismically credible.