A first landslide-induced tsunami generation mapping tool in the Argentinean North Patagonian lakes

DE LUCA, LAUTARO; VILLAROSA, GUSTAVO; BEIGT, DÉBORA; GÓMEZ, EDUARDO ALBERTO

Bariloche

Congreso; IAL IPA 2022; 2022

International Paleolimnology Association - International Association of Limnogeology

Sub-lacustrine landsliding is a geologic hazard of the Argentinean North Patagonian Andes.The main consequences are the impact on submerged or semi-submerged infrastructure,the loss of recreative beach areas, and even the generation of proximal tsunamis thatrepresent a risk for nearby coasts, among others. Currently the assessment of the latterin this region is mostly qualitative (i.e., descriptive) and allows basic inferences, thus it isnecessary the implementation of analysis that enable a quantitative assessment of the hazardthat a landslide-induced tsunami can produce and suitable for producing hazard maps. Inorder to develop a low-cost assessment methodology, easy to transfer to local pertinentinstitutions (e.g., city government), an empirical quantitative approach which works with fewdata input and applies verified analytic solutions in two dimensions, under a freesoftwareenvironment and low-computational costs was chosen. These analytic solutions involvethe hybridization of different methodologies and comprehend the description of hypotheticmass movements, the consequent waves in the surface and the Run-Up over the proximalcoasts. Due to similar physiographic conditions on slope and beach along the delta, a simpleactualist approach was used to translate 2D Run-Up values. In Ñirihuau Delta test area(41°4’48.19”S-71°10’42.39”W), in which ca. 70 events were morphometrically characterized,preliminary results show that in most cases, the Run-Up constitutes a hazard mainly for thecoastal area. The main susceptibility was found on the river outlet. Nearby coastal streetswere affected only under the worst-case scenario prediction (i.e., maximum Run-Up andmaximum seasonal lacustrine level). Although hybridization methodology outputs seemreasonable so far, scarce tsunami event records in the region added to the absence ofdeterministic models for contrasting purposes, constitutes issues to be resolved in order toapply this first, low-cost approximation in the future.