The Plata Rock Avalanche: Deciphering the Occurrence of This Huge Collapse in a Glacial Valley of the Central Andes (33° S)

Abstract

This paper reviews the genesis of a chaotic deposit in the Blanco River basin (BRB) in the Argentine Andes that has been interpreted to be either of debris flow or glacial origin. A detailed sedimentological and geomorphic study of the deposit was undertaken to determine its origin. Glacial landforms in the source area of the deposit contrast markedly to those in neighboring valleys of the BRB. The lack of moraines and the presence only of rock glaciers in the headwaters of the Angostura Valley suggest that a glacier might have been destroyed by a rock avalanche in the Late Pleistocene. The deposit itself has the characteristics of rapid deposition by a huge (≤10 5 m 3) rock avalanche sourced on the eastern slope of Mount Plata (5,956 m asl). The rock avalanche traveled a distance of 26.6 km and descended 4,700 m in altitude. The optically stimulated luminescence (OSL) ages on alluvial sediments associated with the landslide deposits suggest that the rock avalanche occurred ∼35-39 ka ago. The rock avalanche may have been triggered by an earthquake, given that the active Carrera fault system extends across the basin and there is a cluster of seven Late Pleistocene rock avalanches in the region.

Effect of structural setting of source volume on rock avalanche mobility and deposit morphology

“…In previous studies, the deposits of rock avalanches have been extensively investigated to reveal the kinematics of rock avalanches during motion. For a rock avalanche's deposit, the spatial distribution of particle size (Gray and Hutter, 1997;Zeng et al, 2020;Zhao et al, 2021;Baker et al, 2016;Getahun et al, 2019;Dufresne et al, 2016) and the arrangement of blocks (Pánek et al, 2008;Wang et al, 2019;Moreiras, 2020;Dufresne et al, 2021) are prominent features requiring thorough examination. In fact, the latter has become a hotspot for investigation.…”

Debris Flows Occurrence in the Semiarid Central Andes under Climate Change Scenario

“…As in other high mountain ranges around the world, landslide processes are widespread in the Central Andes of Chile and Argentina [1][2][3][4][5]. Geomorphological studies have described paleo-landslides in the Central Andes [6][7][8][9]; however, studies of the most dangerous and impacting events such as debris flows are rare. These sudden events have generated many fatalities, destruction along international transportation corridors, road damages, house destructions, traffic interruptions, infrastructures damages, and complications on drinking water supply with underestimated regional economical loses [10][11][12].…”