A New Landslide Inventory for the Armenian Lesser Caucasus: Slope Failure Morphologies and Seismotectonic Influences on Large Landslides

Abstract

Landslide hazard analyses in Armenia require consideration of the seismotectonic context of the Lesser Caucasus. As it is located near the center of the Arab-Eurasian collision, the Lesser Caucasus is characterized by its complex geology, dense fault network and mountainous relief; it is marked by recent volcanic and seismic activity largely influencing slope stability at different scales. We therefore sought to identify all major landslides in the Armenian Lesser Caucasus and to understand the environmental factors contributing to regional landslide susceptibility. We performed spatial and size-frequency analyses using two landslide catalogues as inputs: “Georisk”, provided by the Georisk Scientific Research Company, and “Matossian”, herein. Our spatial analyses show that landslide susceptibility depends on many factors according to the area considered: near faults, a tectonic influence on slope stability is clearly observable, whereas high concentrations of landslides in northern mountain regions, marked by a wetter climate and far from known active faults, show that climatic factors also strongly contribute to slope-failure potential. The influence of volcanoes and volcanic deposits on the development of mass movements is unclear and requires further analysis. The aforementioned inventories do not include any records of volcanic flank collapses, although we expect at least one case in the eastern Lesser Caucasus.

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

“…In these mountain belts, landslides typically cover >1 % of the landscape. For example, landslides cover approximately 2 % in the Southern Alps of New Zealand (Allen et al, 2011), 5.6 % in the European Alps (Crosta et al, 2013), 4 % of the Armenian part of the Lesser Caucasus (Matossian et al, 2020), and 1.1 % in the Southern Carpathians (Gunnell et al, 2022). However, in the examples mentioned, the percentages of landslide coverage represent only minimum values as they only consider the distribution of rock-slope failures, neglecting shallow/ debris slides and flows.…”

“…In tectonically active areas, such as the Kura fold-and-thrust belt, seismicity is a key trigger for landslides (Keefer, 1984;Tibaldi et al, 1995;Fan et al, 2019;Görüm et al, 2014;Tanyas ¸ and Lombardo, 2019;. Landslides induced by earthquakes resulting from the ongoing collision between the Arabian and Eurasian plates have been documented in surrounding regions, both in the Caucasus (Jibson et al, 1994;Matossian et al, 2020) and Anatolia (Görüm, 2019;Görüm et al, 2023). While earthquakes may have triggered landslides in the Kura fold-and-thrust belt in the past, the distribution of recently identified landslide clusters cannot be explained by seismic activity.…”

First pollen record from the Late Holocene forest environment in the Lesser Caucasus

“…From a geological point of view, the Sevan-Shirak region is made of Eocene tuff and sandstone with andesite. Along the Pambak-Sevan-Syunik fault, the basin of the River Getik is an active fault where numerous landslides occurred (Karakhanian et al, 2002;Matossian et al, 2020). Gravitational hazard is characterised by boulder and block falls, mudflows and huge landslides within the middle-and high-mountain belt, where volcanogenic-sedimentary rocks and tectonic faulting zones have been evidences (Boynagryan et al, 2018).…”