Trenching the Greater Caucasus Frontal Thrusts

Ian Pierce, Sabina Kazimova, Neill Marshall, Ben Johnson, & Richard Walker

Submitted September 11, 2022, SCEC Contribution #12194, 2022 SCEC Annual Meeting Poster #090

Here we present the results of the first paleoseismic investigation of the Greater Caucasus Frontal Thrust in Azerbaijan. The Greater Caucasus Thrust is an imbricate fold and thrust belt extending nearly 900 km from the Caspian Sea to the Black Sea. In Azerbaijan, this frontal belt is the most active part of the subduction zone, and both GPS and structural geologic data show that it accommodates nearly 10 mm/yr of north-directed crustal shortening between Eurasia and the Iranian plate. Azerbaijan has experienced numerous historical devestating earthquakes, including estimated ~M6.9-7 events in 1667 and 1902 that destroyed the historical capital city of Shemakhi. To this day, the causative faults of these events remain unknown. A spring 2022 field campaign produced a single trench across a 1.5-m-high fault scarp in a small alluvial valley near Agsu, Azerbaijan, less than 20 km from Shemakhi. A faulted colluvial wedge deposit, and faulted and folded sediments provide clear evidence of at least two paleoseismic events. Radiocarbon dating of shells and charcoal recoverd from these sediments show that the timing of these earthquakes coincided with both the 1902 and 1667 historical earthquakes. These results provide a first step towards building a paleoseismic history of the many faults of Azerbaijan, improving regional seismic hazard models, and towards understanding the tectonics of the Greater Caucasus.

Pierce, I., Kazimova, S., Marshall, N., Johnson, B., & Walker, R. (2022, 09). Trenching the Greater Caucasus Frontal Thrusts. Poster Presentation at 2022 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Geology