Only one major natural disaster struck Constantinople in the period ca. 750-850 A.D. This was the earthquake of February 9, 790 which forced people to sleep outdoors in tents and prompted the imperial family to vacate the imperial palace for a time, but which apparently spared the city the high levels of death and physical destruction caused by earthquakes in earlier decades.
Emperor Constantine VI Porphyrogenitos (780-798) and his mother Empress Irene with their family and court went to their residence in St. Mamas, located north of the old city in modern-day Besiktas.
According to the Great Lavra Codex, Constantinople shook for several days. A large area of the wall of the City fell, churches were cracked and houses fell. The Emperor with the Patriarch and the people did processions with the Honorable Cross, holy relics and three icons, praying and fasting with tears that God would have mercy on them and avert His wrath. The Lord became the hope of all and the shaking of the earth ceased.
This earthquake is commemorated annually on March 17th.