The 1138 Aleppo earthquake was an earthquake that was located near the town of Aleppo in northern Syria on 11 October 1138. The United States Geological Survey lists it as the fourth deadliest earthquake in history.http://earthquake.usgs.gov/regional/world/most_destructive.php Most Destructive Known Earthquakes on Record in the World, United States Geological Survey However, the figure of 230,000 dead is based on a historical conflation of this earthquake with earthquakes in November 1137 on the Jazira plain and the large seismic event of 30 September 1139 in the Persian city of Ganja. The first mention of a 230,000 death toll was by Ibn Taghribirdi in the fifteenth century.Ambraseys, Nicholas N., http://www.earth-prints.org/bitstream/2122/793/1/31Ambraseys.pdf "The 12th century seismic paroxysm in the Middle East: a historical perspective" (PDF), Annals of Geophysics, Vol. 47, N. 2/3, April/June 2004, p. 743.