A massive 1139 earthquake reshaped the Caucasus landscape and created seven new mountain lakes

Countries & Cities · Published 15 October 2026 Swipe more like this →

In short: In 1139, a catastrophic earthquake struck the Seljuk Empire, triggering landslides so powerful they dammed rivers and birthed new lakes. While historical records suggest a staggering death toll of up to 300,000, modern scholars debate whether this figure is accurate or a conflation of multiple regional disasters from that era.

The 1139 Ganja earthquake remains one of the most significant seismic events in history, occurring within a volatile collision zone between the Eurasian and Arabian tectonic plates. Centered near Ganja in modern-day Azerbaijan, the quake was driven by the Pambak-Sevan-Syunik Fault. This 490-kilometer-long strike-slip fault ruptured along its Mrav segment, where north-dipping thrust faults caused intense crustal compression. Estimates place the earthquake's magnitude between 7.0 and 7.7, with a focal depth of 16 to 23 kilometers. The shaking was so severe that it reached an intensity of IX to XI on the Mercalli scale, with tremors felt as far away as Aleppo.

The physical transformation of the landscape was immediate and dramatic. Massive landslides cascaded down the Caucasus Mountains, burying villages, monasteries, and castles. One of the most notable geological consequences was the collapse of parts of Mount Kapaz, which blocked the flow of the Kürəkçay River. This obstruction created Lake Göygöl, along with six other bodies of water, including Maral-gol and Lake Ağgöl. The destruction was so widespread that the Armenian scholar Mkhitar Gosh famously invoked biblical passages to describe the devastation in the districts of P'ar'isos and Xach'e'n.

The human cost of the event is a subject of intense historical debate. While traditional estimates cite between 230,000 and 300,000 deaths, many modern researchers view these numbers as significant exaggerations. Some argue that the figure likely conflates the 1139 event with the 1138 Aleppo and 1137 Jazira earthquakes. Regardless of the exact toll, the political fallout was swift; King Demetrius I of Georgia exploited the chaos to loot Ganja, famously seizing the city's ancient gates as a trophy. Despite the ruin, the city was eventually reconstructed under the authority of the Seljuk ruler Qara Sonqor, allowing it to flourish once more.

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