The earthquake of 29 November 1114 CE struck during the night, while the population was asleep, and its effects were experienced directly in and around Kaysun. Matthew of Edessa, who appears to have been living in a monastery just outside Kaysun at the time, provides an eyewitness description of the event from within the epicentral region. He records a violent concussion accompanied by a “horrible, crackling, and reverberating sound,” with plains and mountains shaking, rocks cleaving, hills splitting, and trees swaying as if struck by a fierce wind. He likens the motion of the land to a churned-up sea and notes that the noise continued for roughly an hour after the main trembling, suggesting prolonged aftershocks. The terror produced by the event was such that many believed the Day of Judgment had arrived.

Matthew further reports that extensive destruction occurred during this night. He lists the complete destruction of Samosata, Hisn-Mansur, Kesoun, and Raban. This pattern of devastation is corroborated by later Armenian and Syriac chroniclers, who extend the list of affected cities and emphasize the scale of urban collapse across northern Syria and Upper Mesopotamia. Chronicle of Smbat Sparapet reports that Antioch, Mecis, Hisn-Mansur, Kayšum, Ablastha, Rʿaban, and Samosata were ruined, presenting the earthquake as a regional disaster affecting multiple major centers.

More detailed architectural losses are described by Syriac authors. Michael the Syrian records the collapse of the churches of Mar John and the Forty Martyrs at Kaysun, noting that they were later rebuilt through the efforts of Bishop Dionysius, a detail echoed by Bar Hebraeus. Together, these accounts depict a catastrophic earthquake centered near Kaysun and Marʿash, characterized by intense ground motion, prolonged aftershocks, widespread urban destruction, and significant loss of life.