Constantinople earthquake of 447
447 CE.
Shown on the map at 40.900°, 28.500°.
The area around Constantinople was affected by a major earthquake in AD 447. It caused serious damage to the recently completed Theodosian walls in Constantinople, destroying 57 towers and large stretches of the walls. The historical records contain no mention of casualties directly associated with this earthquake, although many thousands of people were reported to have died in the aftermath due to starvation and a "noxious smell".
Text from the Wikipedia article 447 Constantinople earthquake, licensed CC BY-SA 4.0.