TY - JOUR A1 - Panek, Tomas A1 - Korup, Oliver A1 - Lenart, Jan A1 - Hradecky, Jan A1 - Brezny, Michal T1 - Giant landslides in the foreland of the Patagonian Ice Sheet JF - Quaternary science reviews : the international multidisciplinary research and review journal N2 - Quaternary glaciations have repeatedly shaped large tracts of the Andean foreland. Its spectacular large glacial lakes, staircases of moraine ridges, and extensive outwash plains have inspired generations of scientists to reconstruct the processes, magnitude, and timing of ice build-up and decay at the mountain front. Surprisingly few of these studies noticed many dozens of giant (≥108 m3) mass-wasting deposits in the foreland. We report some of the world's largest terrestrial landslides in the eastern piedmont of the Patagonian Ice Sheet (PIS) along the traces of the former Lago Buenos Aires and Lago Puyerredón glacier lobes and lakes. More than 283 large rotational slides and lateral spreads followed by debris slides, earthflows, rotational and translational rockslides, complex slides and few large rock avalanches detached some 164 ± 56 km3 of material from the slopes of volcanic mesetas, lake-bounding moraines, and river-gorge walls. Many of these landslide deposits intersect with well-dated moraine ridges or former glacial-lake shorelines, and offer opportunities for relative dating of slope failure. We estimate that >60% of the landslide volume (∼96 km3) detached after the Last Glacial Maximum (LGM). Giant slope failures cross-cutting shorelines of a large Late Glacial to Early Holocene lake (“glacial lake PIS”) likely occurred during successive lake-level drop between ∼11.5 and 8 ka, and some of them are the largest hitherto documented landslides in moraines. We conclude that 1) large portions of terminal moraines can fail catastrophically several thousand years after emplacement; 2) slopes formed by weak bedrock or unconsolidated glacial deposits bordering glacial lakes can release extremely large landslides; and 3) landslides still occur in the piedmont, particularly along postglacial gorges cut in response to falling lake levels. KW - Quaternary KW - Landslide KW - Geomorphology KW - Relative dating KW - Glacier foreland KW - Glacial lake KW - Patagonian Ice Sheet KW - Paleogeography KW - South America Y1 - 2018 U6 - https://doi.org/10.1016/j.quascirev.2018.06.028 SN - 0277-3791 VL - 194 SP - 39 EP - 54 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Schönfeldt, Elisabeth A1 - Pánek, Tomáš A1 - Winocur, Diego A1 - Silhan, Karel A1 - Korup, Oliver T1 - Postglacial Patagonian mass movement BT - from rotational slides and spreads to earthflows JF - Geomorphology : an international journal on pure and applied geomorphology N2 - Many of the volcanic plateau margins of the eastern, formerly glaciated, foreland of the Patagonian Andes are undermined by giant landslides (>= 10(8) m(3)). One cluster of such landslides extends along the margin of the Meseta del Lago Buenos Aires (MLBA) plateau that is formed mainly by Neogene-Quaternary basalts. The dry climate is at odds with numerous >2-km long earthflows nested within older and larger compound landslides. We present a hydrological analysis, a detailed geomorphic map, interpretations of exposed landslide interiors, and radiocarbon dating of the El Mirador landslide, which is one of the largest and morphologically most representative landslide. We find that the presence of lakes on top of the plateau, causing low infiltration rates, correlates negatively with the abundance of earthflows on compound landslides along the plateau margins. Field outcrops show that the pattern of compound landslides and earthflows is likely controlled by groundwater seepage at the contact between the basalts and underlying soft Miocene molasse. Numerous peat bogs store water and sediment and are more abundant in earthflow-affected areas than in their contributing catchment areas.
Radiocarbon dates indicate that these earthflows displaced metre-thick layers of peat in the late Holocene (<2.5 ka). We conclude that earthflows of the MLBA plateau might be promising proxies of past hydroclimatic conditions in the Patagonian foreland, if strong earthquakes or gradual crustal stress changes due to glacioisostatic rebound can be ruled out. KW - landslide KW - lateral spread KW - earthflow KW - Patagonia Y1 - 2020 U6 - https://doi.org/10.1016/j.geomorph.2020.107316 SN - 0169-555X SN - 1872-695X VL - 367 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Panek, Tomas A1 - Korup, Oliver A1 - Minar, Jozef A1 - Hradecky, Jan T1 - Giant landslides and highstands of the Caspian Sea JF - Geology Y1 - 2016 U6 - https://doi.org/10.1130/G38259.1 SN - 0091-7613 SN - 1943-2682 VL - 44 SP - 939 EP - 942 PB - American Institute of Physics CY - Boulder ER - TY - JOUR A1 - Schönfeldt, Elisabeth A1 - Winocur, Diego A1 - Pánek, Tomáš A1 - Korup, Oliver T1 - Deep learning reveals one of Earth's largest landslide terrain in Patagonia JF - Earth & planetary science letters N2 - Hundreds of basaltic plateau margins east of the Patagonian Cordillera are undermined by numerous giant slope failures. However, the overall extent of this widespread type of plateau collapse remains unknown and incompletely captured in local maps. To detect giant slope failures consistently throughout the region, we train two convolutional neural networks (CNNs), AlexNet and U-Net, with Sentinel-2 optical data and TanDEM-X topographic data on elevation, surface roughness, and curvature. We validated the performance of these CNNs with independent testing data and found that AlexNet performed better when learned on topographic data, and UNet when learned on optical data. AlexNet predicts a total landslide area of 12,000 km2 in a study area of 450,000 km2, and thus one of Earth's largest clusters of giant landslides. These are mostly lateral spreads and rotational failures in effusive rocks, particularly eroding the margins of basaltic plateaus; some giant landslides occurred along shores of former glacial lakes, but are least prevalent in Quaternary sedimentary rocks. Given the roughly comparable topographic, climatic, and seismic conditions in our study area, we infer that basalts topping weak sedimentary rocks may have elevated potential for large-scale slope failure. Judging from the many newly detected and previously unknown landslides, we conclude that CNNs can be a valuable tool to detect large-scale slope instability at the regional scale. However, visual inspection is still necessary to validate results and correctly outline individual landslide source and deposit areas. KW - landslide detection KW - convolutional neural network KW - Patagonia Y1 - 2022 U6 - https://doi.org/10.1016/j.epsl.2022.117642 SN - 0012-821X SN - 1385-013X VL - 593 PB - Elsevier CY - Amsterdam [u.a.] ER - TY - JOUR A1 - Pánek, Tomáš A1 - Břežný, Michal A1 - Harrison, Stephan A1 - Schönfeldt, Elisabeth A1 - Winocur, Diego T1 - Large landslides cluster at the margin of a deglaciated mountain belt JF - Scientific reports N2 - Landslides in deglaciated and deglaciating mountains represent a major hazard, but their distribution at the spatial scale of entire mountain belts has rarely been studied. Traditional models of landslide distribution assume that landslides are concentrated in the steepest, wettest, and most tectonically active parts of the orogens, where glaciers reached their greatest thickness. However, based on mapping large landslides (>0.9 km(2)) over an unprecedentedly large area of Southern Patagonia (similar to 305,000 km(2)), we show that the distribution of landslides can have the opposite trend. We show that the largest landslides within the limits of the former Patagonian Ice Sheet (PIS) cluster along its eastern margins occupying lower, tectonically less active, and arid part of the Patagonian Andes. In contrast to the heavily glaciated, highest elevations of the mountain range, the peripheral regions have been glaciated only episodically, leaving a larger volume of unstable sedimentary and volcanic rocks that are subject to ongoing slope instability. Y1 - 2022 U6 - https://doi.org/10.1038/s41598-022-09357-9 SN - 2045-2322 VL - 12 IS - 1 PB - Macmillan Publishers Limited, part of Springer Nature CY - London ER -