Seismological study around the Enguri dam reservoir (Georgia) based on old catalogs and ongoing monitoring

Abstract

In the frame of the DAMAST (Dams and Seismicity) project, we deployed a dense high-fidelity seismological real-time network to investigate in detail the spatio-temporal seismicity distribution around the Enguri high dam, situated in the greater Caucasus in western Georgia. We aim at recording the weak seismicity in a 10 km distance around the dam structure. To lower the detection threshold by reducing the ambient background noise, we installed four seismic stations in shallow (ca. 20 m) and deep boreholes. From these stations, KIT1 with a depth of ca. 250 m is the deepest seismological station in Georgia. In this paper, we characterize the seismicity recorded by the local seismic network from October 2020 to July 2022. To have a better historical picture of the seismic activity, especially since the dam construction and initial operations, re-processing of the old seismological catalogs was carried out. This required digitizing the paper-only catalog copies prior to relocation. We finally obtain a uniform catalog for the Enguri region to characterize the seismicity and start investigating its possible relationship with the exploitation of the dam reservoirs.

Spectral Investigation of the Relationship between Seismicity and Water Level in the Enguri High Dam Area (Georgia)

“…The Enguri area, situated in western Georgia, is characterized by three main tectonic units, each with distinct geological development structures. A comprehensive description of these units is provided in a recent publication by Karamzadeh et al [54]. The intricate network of faults mapped in Georgia relies predominantly on the displacement observed in key geological units.…”

“…The new seismic network installed under the DAMAST project indicates high seismic activity in this area. From 2020 onwards, several hundred swarms of microearthquakes have occurred, although magnitude estimation for these events is challenging as they are recorded on only one station [54]. Figure 1 illustrates the investigated seismicity within a 50 km radius around the Enguri dam (from 1978 to 2021).…”