Insights into earthquake-induced tsunamis in the Caucasus’ largest Lake Sevan

By leveraging the Okada model, the study makes the first-ever attempt to examine earthquake-induced tsunamis in Lake Sevan, related to the activation of underwater segments of the active Pambak-Sevan-Syunik Fault (PSSF), the largest geological structure in the Republic of Armenia (RA). Situated in the Arabian-Eurasian continental collision zone, the basin of Sevan, the largest freshwater lake in the Caucasus region, is characterized by a variety of geological hazards capable of producing events of inter-related triggering. Among other threats, the lake tsunami hazard has remained unexplored. Two hypothetical earthquake scenarios were computed for the PSSF segments: an Mw 6.9 for the sector of the Vanadzor-Artanish segment as a reverse faulting and an Mw 7.5 for the Dzknaget-Khonarhasar strike-slip. The best-fit solutions, as fault-derived parameters, were calibrated under the proposed seismic scenarios. Based on the fault parameters, a back-analysis was first performed to determine earthquake magnitudes and to develop appropriate scenarios for the subsequent lake tsunami simulation. Finally, potential tsunami wave maps were produced for the tsunami hazard in Lake Sevan. The shores of the Small Sevan were identified as the possibly most impacted zone with maximum wave height (Zmax) of 4 meters estimated under the Mw 6.9 scenario for the sector of the Vanadzor-Artanish segment.