Age, kinematics, and magnitude of the last surface rupturing event along the central Pambak-Sevan-Syunik fault (Armenia): Probable implications for landslides and lake tsunamis

Abstract

The Lesser Caucasus region is located in the northern part of the Armenian Highland, within the active Arabia-Eurasian collision zone. Numerous and various geological hazards, such as large earthquakes can be observed in this region. They can reach M7^± magnitude inducing surface ruptures and strong ground shaking that in turn can trigger landslides and liquefaction phenomena. One of the most important sources of earthquakes is the Pambak-Sevan-Syunik fault (PSSF), which crosses the entire Armenian territory including Lake Sevan with population estimated at 280,000 around it. In this work, we conducted a paleoseismological study along the Vanadzor-Artanish segment of the PSSF, on the northern shore of the Lake Sevan. Our findings indicate that this fault produced a M_w 7.2 earthquake between 901 and 2333 cal. BC resulting in a surface rupture of at least 22 km and a vertical displacement component of approximately 2 m. Based on our observations, this large earthquake most likely triggered associated phenomena such as landslides and a lake tsunami. These new results demonstrate that characterizing the paleoseismology of active faults in mountainous regions, especially in densely populated areas like Armenia, must be combined with the analysis of potential associated phenomena to provide a complete geohazards assessment.