Assessment of geodynamic risk of Mingachevir water reservoir

Abstract

The paper presents the results of the analysis of seismicity, tectonics and the manifestations of induced seismicity in the area of the Mingachevir reservoir for the period 2008-2017. Local earthquakes that occur when the Mingachevir reservoir is filled have insignificant magnitudesless than 2-2.5, tremors with a magnitude of 3.5 are less common. Epicenters are located mainly at a distance of no more than 5-10 km. Data analysis showed that seismic activity increases when the pressure reaches 78 m or more. Based on the mechanisms of the earthquake source, maps of the distribution of compressive and extension stresses in the horizontal plane and in depth were constructed. It was found that the northwestern part of the study area is characterized by extension and compression in the south and southeast. Analysis of seismic activity observation data showed the dependence of the rate of change of the water level in the reservoir with the seismic activity of weak earthquakes, which is non-linear. The rise in water level lasts 5 months, from March to June. In August the water level at the beginning drops gradually and then sharply (from 80-78 m to 74-73 m). As a result of the drop in water level in this area the induced seismicity increased. In 2010 the water level in the Mingachevir reservoir increased from 78-79 meters in March to 82-83 meters in May, caused an increase in the water level in the Kura River and attracted flooding. An analysis of seismicity for this period showed that in February, March, April, July and August 21 earthquakes with magnitudes of 1.2-3.0 occurred in this region

Landslides and growing folds: A lesson from the Kura fold-and-thrust belt (Azerbaijan, Georgia)

“…More attention was paid only to landslides around the shoreline of Mingachevir reservoir (Yetirmishli et al, 2018). Several planar slides on the limbs of the anticline, which are susceptible to reactivations triggered by fluctuations in water levels, have been documented, particularly along the southern bank of the Mingachevir reservoir in close proximity to the dam site (Kotyuzhan and Molokov, 1990;Bairamov et al, 1992;Islamova et al, 2019).…”

“…11a, the density of landslides on the Boz Dag anticline increases from both plunging noses of the anticline towards its central part. Although some landslides along the northern flank of the anticline may have originated due to groundwater rise related to the filling of the Mingachevir Reservoir in 1959 (Kotyuzhan and Molokov, 1990;Bairamov et al, 1992;Yetirmishli et al, 2018;Islamova et al, 2019), the distribution of landslides on both flanks of the anticline is clearly controlled by the local slope steepness and the dip of the beds. Landslides are completely absent on both low plunging noses of the anticline, and their occurrence is strictly confined to the highest central segment where the average dip of the beds exceeds 10 • (Fig.…”

“…While some mapped landslides may have been caused by past seismicity, almost a millennium has passed since the last significant earthquake, the M~7 AD 1139 Ganja earthquake (Ismail-Zadeh et al, 2020). Consequently, many landslides, especially in actively incising valleys and on dip slopes on anticlinal limbs, have likely been triggered by other factors, such as heavy rainfall, river undercutting, or anthropogenic activities (Kotyuzhan and Molokov, 1990;Bairamov et al, 1992;Yetirmishli et al, 2018;Islamova et al, 2019). In other settings, such as fault escarpments distal to actively eroding rivers, we speculate that large, old landslides may have a seismic origin, whereas smaller landslides have been removed due to erosion or anthropogenic activities since the last earthquake.…”