TY - JOUR A1 - Öztürk, Ugur A1 - Marwan, Norbert A1 - von Specht, Sebastian A1 - Korup, Oliver A1 - Jensen, J. T1 - A new centennial sea-level record for Antalya, Eastern Mediterranean JF - Journal of geophysical research-oceans N2 - Quantitative estimates of sea-level rise in the Mediterranean Basin become increasingly accurate thanks to detailed satellite monitoring. However, such measuring campaigns cover several years to decades, while longer-term sea-level records are rare for the Mediterranean. We used a data archeological approach to reanalyze monthly mean sea-level data of the Antalya-I (1935–1977) tide gauge to fill this gap. We checked the accuracy and reliability of these data before merging them with the more recent records of the Antalya-II (1985–2009) tide gauge, accounting for an eight-year hiatus. We obtain a composite time series of monthly and annual mean sea levels spanning some 75 years, providing the longest record for the eastern Mediterranean Basin, and thus an essential tool for studying the region's recent sea-level trends. We estimate a relative mean sea-level rise of 2.2 ± 0.5 mm/year between 1935 and 2008, with an annual variability (expressed here as the standard deviation of the residuals, σresiduals = 41.4 mm) above that at the closest tide gauges (e.g., Thessaloniki, Greece, σresiduals = 29.0 mm). Relative sea-level rise accelerated to 6.0 ± 1.5 mm/year at Antalya-II; we attribute roughly half of this rate (~3.6 mm/year) to tectonic crustal motion and anthropogenic land subsidence. Our study highlights the value of data archeology for recovering and integrating historic tide gauge data for long-term sea-level and climate studies. KW - sea level KW - tide gauge KW - data archeology KW - Mediterranean Sea Y1 - 2018 U6 - https://doi.org/10.1029/2018JC013906 SN - 2169-9275 SN - 2169-9291 VL - 123 IS - 7 SP - 4503 EP - 4517 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Weidinger, Johannes T. A1 - Korup, Oliver A1 - Munack, Henry A1 - Altenberger, Uwe A1 - Dunning, Stuart A. A1 - Tippelt, Gerold A1 - Lottermoser, Werner T1 - Giant rockslides from the inside JF - Earth & planetary science letters N2 - The growing body of research on large-scale mass wasting events so far has only scarcely investigated the sedimentology of chaotic deposits from non-volcanic terrestrial landslides such that any overarching and systematic terminological framework remains elusive. Yet recent work has emphasized the need for better understanding the internal structure and composition of rockslide deposits as a means to characterise the mechanics during the final stages of runout and emplacement. We offer a comprehensive overview on the occurrence of rock fragmentation and frictional melt both at different geographic locations, and different sections within large (>10(6) m(3)) rockslide masses. We argue that exposures of pervasively fragmented and interlocked jigsaw-cracked rock masses; basal melange containing rip-up clasts and phantom blocks; micro-breccia; and thin bands of basal frictionite are indispensable clues for identifying deposits from giant rockslides that may remain morphologically inconspicuous otherwise. These sedimentary assemblages are diagnostic tools for distinguishing large rockslide debris from macro and microscopically similar glacial deposits, tectonic fault-zone breccias, and impact breccias, and thus help avoid palaeoclimatic and tectonic misinterpretations, let alone misestimates of the hazard from giant rockslides. Moreover, experimental results from Mossbauer spectroscopy of frictionite samples support visual interpretations of thin sections, and demonstrate that short-lived (<10 s) friction-induced partial melting at temperatures >1500 degrees C in the absence of water occurred at the base of several giant moving rockslides. This finding supports previous theories of dry excess runout accompanied by comminution of rock masses down to gm-scale, and indicates that catastrophic motion of large fragmenting rock masses does not require water as a potential lubricant. KW - landslide KW - petrography KW - frictional melt KW - pseudotachylyte KW - breccia KW - Mossbauer spectroscopy Y1 - 2014 U6 - https://doi.org/10.1016/j.epsl.2013.12.017 SN - 0012-821X SN - 1385-013X VL - 389 SP - 62 EP - 73 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Wang, Yongbo A1 - Herzschuh, Ulrike A1 - Liu, Xingqi A1 - Korup, Oliver A1 - Diekmann, Bernhard T1 - A high-resolution sedimentary archive from landslide-dammed Lake Mengda, north-eastern Tibetan Plateau JF - Journal of paleolimnolog N2 - Lacustrine sediments have been widely used to investigate past climatic and environmental changes on millennial to seasonal time scales. Sedimentary archives of lakes in mountainous regions may also record non-climatic events such as earthquakes. We argue herein that a set of 64 annual laminae couplets reconciles a stratigraphically inconsistent accelerator mass spectrometry (AMS) C-14 chronology in a similar to 4-m-long sediment core from Lake Mengda, in the north-eastern Tibetan Plateau. The laminations suggest the lake was formed by a large landslide, triggered by the 1927 Gulang earthquake (M = 8.0). The lake sediment sequence can be separated into three units based on lithologic, sedimentary, and isotopic characteristics. Starting from the bottom of the sequence, these are: (1) unweathered, coarse, sandy valley-floor deposits or landslide debris that pre-date the lake, (2) landslide-induced, fine-grained soil or reworked landslide debris with a high organic content, and (3) lacustrine sediments with low organic content and laminations. These annual laminations provide a high-resolution record of anthropogenic and environmental changes during the twentieth century, recording enhanced sediment input associated with two phases of construction activities. The high mean sedimentation rates of up to 4.8 mm year(-1) underscore the potential for reconstructing such distinct sediment pulses in remote, forested, and seemingly undisturbed mountain catchments. KW - Earthquake KW - Landslide KW - Natural dam KW - Tibetan Plateau Y1 - 2014 U6 - https://doi.org/10.1007/s10933-012-9666-6 SN - 0921-2728 SN - 1573-0417 VL - 51 IS - 2 SP - 303 EP - 312 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - von Specht, Sebastian A1 - Öztürk, Ugur A1 - Veh, Georg A1 - Cotton, Fabrice A1 - Korup, Oliver T1 - Effects of finite source rupture on landslide triggering BT - the 2016 M-w 7.1 Kumamoto earthquake JF - Solid earth N2 - The propagation of a seismic rupture on a fault introduces spatial variations in the seismic wave field surrounding the fault. This directivity effect results in larger shaking amplitudes in the rupture propagation direction. Its seismic radiation pattern also causes amplitude variations between the strike-normal and strike-parallel components of horizontal ground motion. We investigated the landslide response to these effects during the 2016 Kumamoto earthquake (M-w 7.1) in central Kyushu (Japan). Although the distribution of some 1500 earthquake-triggered landslides as a function of rupture distance is consistent with the observed Arias intensity, the landslides were more concentrated to the northeast of the southwest-northeast striking rupture. We examined several landslide susceptibility factors: hillslope inclination, the median amplification factor (MAF) of ground shaking, lithology, land cover, and topographic wetness. None of these factors sufficiently explains the landslide distribution or orientation (aspect), although the landslide head scarps have an elevated hillslope inclination and MAF. We propose a new physics-based ground-motion model (GMM) that accounts for the seismic rupture effects, and we demonstrate that the low-frequency seismic radiation pattern is consistent with the overall landslide distribution. Its spatial pattern is influenced by the rupture directivity effect, whereas landslide aspect is influenced by amplitude variations between the fault-normal and fault-parallel motion at frequencies < 2 Hz. This azimuth dependence implies that comparable landslide concentrations can occur at different distances from the rupture. This quantitative link between the prevalent landslide aspect and the low-frequency seismic radiation pattern can improve coseismic landslide hazard assessment. Y1 - 2019 U6 - https://doi.org/10.5194/se-10-463-2019 SN - 1869-9510 SN - 1869-9529 VL - 10 IS - 2 SP - 463 EP - 486 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Vogel, Kristin A1 - Riggelsen, Carsten A1 - Korup, Oliver A1 - Scherbaum, Frank T1 - Bayesian network learning for natural hazard analyses JF - Natural hazards and earth system sciences N2 - Modern natural hazards research requires dealing with several uncertainties that arise from limited process knowledge, measurement errors, censored and incomplete observations, and the intrinsic randomness of the governing processes. Nevertheless, deterministic analyses are still widely used in quantitative hazard assessments despite the pitfall of misestimating the hazard and any ensuing risks. In this paper we show that Bayesian networks offer a flexible framework for capturing and expressing a broad range of uncertainties encountered in natural hazard assessments. Although Bayesian networks are well studied in theory, their application to real-world data is far from straightforward, and requires specific tailoring and adaptation of existing algorithms. We offer suggestions as how to tackle frequently arising problems in this context and mainly concentrate on the handling of continuous variables, incomplete data sets, and the interaction of both. By way of three case studies from earthquake, flood, and landslide research, we demonstrate the method of data-driven Bayesian network learning, and showcase the flexibility, applicability, and benefits of this approach. Our results offer fresh and partly counterintuitive insights into well-studied multivariate problems of earthquake-induced ground motion prediction, accurate flood damage quantification, and spatially explicit landslide prediction at the regional scale. In particular, we highlight how Bayesian networks help to express information flow and independence assumptions between candidate predictors. Such knowledge is pivotal in providing scientists and decision makers with well-informed strategies for selecting adequate predictor variables for quantitative natural hazard assessments. Y1 - 2014 U6 - https://doi.org/10.5194/nhess-14-2605-2014 SN - 1561-8633 VL - 14 IS - 9 SP - 2605 EP - 2626 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Vogel, Kristin A1 - Ozturk, Ugur A1 - Riemer, Adrian A1 - Laudan, Jonas A1 - Sieg, Tobias A1 - Wendi, Dadiyorto A1 - Agarwal, Ankit A1 - Roezer, Viktor A1 - Korup, Oliver A1 - Thieken, Annegret T1 - Die Sturzflut von Braunsbach am 29. Mai 2016 – Entstehung, Ablauf und Schäden eines „Jahrhundertereignisses“ T1 - The Braunsbach Flashflood of Mai 29th, 2016-Origin, Pathways and Impacts of an Extreme Hydro-Meteorological Event BT - Teil 2: Geomorphologische Prozesse und Schadensanalyse BT - Part 2: Geomorphological Processes and Damage Analysis JF - Hydrologie und Wasserbewirtschaftung N2 - Am Abend des 29. Mai 2016 wurde der Ort Braunsbach im Landkreis Schwäbisch-Hall (Baden-Württemberg) von einer Sturzflut getroffen, bei der mehrere Häuser stark beschädigt oder zerstört wurden. Die Sturzflut war eine der Unwetterfolgen, die im Frühsommer 2016 vom Tiefdruckgebiet Elvira ausgelöst wurden. Der vorliegende Bericht ist der zweite Teil einer Doppelveröffentlichung, welche die Ergebnisse zur Untersuchung des Sturzflutereignisses im Rahmen des DFG-Graduiertenkollegs “Naturgefahren und Risiken in einer sich verändernden Welt” (NatRiskChange, GRK 2043/1) der Universität Potsdam präsentiert. Während Teil 1 die meteorologischen und hydrologischen Ereignisse analysiert, fokussiert Teil 2 auf die geomorphologischen Prozesse und die verursachten Gebäudeschäden. Dazu wurden Ursprung und Ausmaß des während des Sturzflutereignisses mobilisierten und in den Ort getragenen Materials untersucht. Des Weiteren wurden zu 96 betroffenen Gebäuden Daten zum Schadensgrad sowie Prozess- und Gebäudecharakteristika aufgenommen und ausgewertet. Die Untersuchungen zeigen, dass bei der Betrachtung von Hochwassergefährdung die Berücksichtigung von Sturzfluten und ihrer speziellen Charakteristika, wie hoher Feststofftransport und sprunghaftes Verhalten insbesondere in bebautem Gelände, wesentlich ist, um effektive Schutzmaßnahmen ergreifen zu können. N2 - A severe flash flood event hit the town of Braunsbach (Baden-Wurttemberg, Germany) on the evening of May 29, 2016, heavily damaging and destroying several dozens of buildings. It was only one of several disastrous events in Central Europe caused by the low-pressure system "Elvira". The DFG Graduate School "Natural hazards and risks in a changing world" (NatRiskChange, GRK 2043/1) at the University of Potsdam investigated the Braunsbach flash flood as a recent showcase for catastrophic events triggered by severe weather. This contribution is part two of a back-to-back publication on the results of this storm event. While part 1 analyses the meteorological and hydrological situation, part 2 concentrates on the geomorphological aspects and damage to buildings. The study outlines the origin and amount of material that was mobilized and transported into the town by the flood, and analyses damage data collected for 96 affected buildings, describing the degree of impact, underlying processes, and building characteristics. Due to the potentially high sediment load of flash floods and their non-steady and non-uniform flow especially in built-up areas, the damaging processes differ from those of clear water floods. The results underline the need to consider flash floods and their specific behaviour in flood hazard assessments. KW - flash flood KW - flood risk KW - damaging processes KW - debris flow KW - erosion KW - landslides KW - Braunsbach KW - Sturzflut KW - Hochwassergefährdung KW - Schadensprozesse KW - Erosion KW - Hangrutschungen Y1 - 2017 U6 - https://doi.org/10.5675/HyWa_2017,3_2 SN - 1439-1783 VL - 61 IS - 3 SP - 163 EP - 175 PB - Bundesanst. für Gewässerkunde CY - Koblenz ER - TY - JOUR A1 - Veh, Georg A1 - Lützow, Natalie A1 - Kharlamova, Varvara A1 - Petrakov, Dmitry A1 - Hugonnet, Romain A1 - Korup, Oliver T1 - Trends, Breaks, and Biases in the Frequency of Reported Glacier Lake Outburst Floods JF - Earth's Future N2 - Thousands of glacier lakes have been forming behind natural dams in high mountains following glacier retreat since the early 20th century. Some of these lakes abruptly released pulses of water and sediment with disastrous downstream consequences. Yet it remains unclear whether the reported rise of these glacier lake outburst floods (GLOFs) has been fueled by a warming atmosphere and enhanced meltwater production, or simply a growing research effort. Here we estimate trends and biases in GLOF reporting based on the largest global catalog of 1,997 dated glacier-related floods in six major mountain ranges from 1901 to 2017. We find that the positive trend in the number of reported GLOFs has decayed distinctly after a break in the 1970s, coinciding with independently detected trend changes in annual air temperatures and in the annual number of field-based glacier surveys (a proxy of scientific reporting). We observe that GLOF reports and glacier surveys decelerated, while temperature rise accelerated in the past five decades. Enhanced warming alone can thus hardly explain the annual number of reported GLOFs, suggesting that temperature-driven glacier lake formation, growth, and failure are weakly coupled, or that outbursts have been overlooked. Indeed, our analysis emphasizes a distinct geographic and temporal bias in GLOF reporting, and we project that between two to four out of five GLOFs on average might have gone unnoticed in the early to mid-20th century. We recommend that such biases should be considered, or better corrected for, when attributing the frequency of reported GLOFs to atmospheric warming. Y1 - 2022 U6 - https://doi.org/10.1029/2021EF002426 SN - 2328-4277 VL - 10 SP - 1 EP - 14 PB - Wiley-Blackwell CY - Hoboken, New Jersey, United States ET - 3 ER - TY - JOUR A1 - Veh, Georg A1 - Lützow, Natalie A1 - Kharlamova, Varvara A1 - Petrakov, Dmitry A1 - Hugonnet, Romain A1 - Korup, Oliver T1 - Trends, breaks, and biases in the frequency of reported glacier lake outburst floods JF - Earth's future N2 - Thousands of glacier lakes have been forming behind natural dams in high mountains following glacier retreat since the early 20th century. Some of these lakes abruptly released pulses of water and sediment with disastrous downstream consequences. Yet it remains unclear whether the reported rise of these glacier lake outburst floods (GLOFs) has been fueled by a warming atmosphere and enhanced meltwater production, or simply a growing research effort. Here we estimate trends and biases in GLOF reporting based on the largest global catalog of 1,997 dated glacier-related floods in six major mountain ranges from 1901 to 2017. We find that the positive trend in the number of reported GLOFs has decayed distinctly after a break in the 1970s, coinciding with independently detected trend changes in annual air temperatures and in the annual number of field-based glacier surveys (a proxy of scientific reporting). We observe that GLOF reports and glacier surveys decelerated, while temperature rise accelerated in the past five decades. Enhanced warming alone can thus hardly explain the annual number of reported GLOFs, suggesting that temperature-driven glacier lake formation, growth, and failure are weakly coupled, or that outbursts have been overlooked. Indeed, our analysis emphasizes a distinct geographic and temporal bias in GLOF reporting, and we project that between two to four out of five GLOFs on average might have gone unnoticed in the early to mid-20th century. We recommend that such biases should be considered, or better corrected for, when attributing the frequency of reported GLOFs to atmospheric warming. KW - glaciers KW - climate change KW - hazard KW - mountains KW - cryosphere KW - frequency Y1 - 2022 U6 - https://doi.org/10.1029/2021EF002426 SN - 2328-4277 VL - 10 IS - 3 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Veh, Georg A1 - Korup, Oliver A1 - Walz, Ariane T1 - Hazard from Himalayan glacier lake outburst floods JF - Proceedings of the National Academy of Sciences of the United States of America : PNAS N2 - Sustained glacier melt in the Himalayas has gradually spawned more than 5,000 glacier lakes that are dammed by potentially unstable moraines. When such dams break, glacier lake outburst floods (GLOFs) can cause catastrophic societal and geomorphic impacts. We present a robust probabilistic estimate of average GLOFs return periods in the Himalayan region, drawing on 5.4 billion simulations. We find that the 100-y outburst flood has an average volume of 33.5(+3.7)/(-3.7) x 10(6) m(3) (posterior mean and 95% highest density interval [HDI]) with a peak discharge of 15,600(+2.000)/(-1,800) m(3).S-1. Our estimated GLOF hazard is tied to the rate of historic lake outbursts and the number of present lakes, which both are highest in the Eastern Himalayas. There, the estimated 100-y GLOF discharge (similar to 14,500 m(3).s(-1)) is more than 3 times that of the adjacent Nyainqentanglha Mountains, and at least an order of magnitude higher than in the Hindu Kush, Karakoram, and Western Himalayas. The GLOF hazard may increase in these regions that currently have large glaciers, but few lakes, if future projected ice loss generates more unstable moraine-dammed lakes than we recognize today. Flood peaks from GLOFs mostly attenuate within Himalayan headwaters, but can rival monsoon-fed discharges in major rivers hundreds to thousands of kilometers downstream. Projections of future hazard from meteorological floods need to account for the extreme runoffs during lake outbursts, given the increasing trends in population, infrastructure, and hydropower projects in Himalayan headwaters. KW - atmospheric warming KW - meltwater lakes KW - GLOF KW - extreme-value statistics KW - Bayesian modeling Y1 - 2019 U6 - https://doi.org/10.1073/pnas.1914898117 SN - 0027-8424 VL - 117 IS - 2 SP - 907 EP - 912 PB - National Academy of Sciences CY - Washington ER - TY - JOUR A1 - Veh, Georg A1 - Korup, Oliver A1 - von Specht, Sebastian A1 - Rößner, Sigrid A1 - Walz, Ariane T1 - Unchanged frequency of moraine-dammed glacial lake outburst floods in the Himalaya JF - Nature climate change N2 - Shrinking glaciers in the Hindu Kush-Karakoram-Himalaya-Nyainqentanglha (HKKHN) region have formed several thousand moraine-dammed glacial lakes(1-3), some of these having grown rapidly in past decades(3,4). This growth may promote more frequent and potentially destructive glacial lake outburst floods (GLOFs)(5-7). Testing this hypothesis, however, is confounded by incomplete databases of the few reliable, though selective, case studies. Here we present a consistent Himalayan GLOF inventory derived automatically from all available Landsat imagery since the late 1980s. We more than double the known GLOF count and identify the southern Himalayas as a hotspot region, compared to the more rarely affected Hindu Kush-Karakoram ranges. Nevertheless, the average annual frequency of 1.3 GLOFs has no credible posterior trend despite reported increases in glacial lake areas in most of the HKKHN3,8, so that GLOF activity per unit lake area has decreased since the late 1980s. We conclude that learning more about the frequency and magnitude of outburst triggers, rather than focusing solely on rapidly growing glacial lakes, might improve the appraisal of GLOF hazards. KW - Climate change KW - Cryospheric science KW - Environmental impact KW - Geomorphology Y1 - 2019 U6 - https://doi.org/10.1038/s41558-019-0437-5 SN - 1758-678X SN - 1758-6798 VL - 9 IS - 5 SP - 379 EP - 383 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Veh, Georg A1 - Korup, Oliver A1 - Roessner, Sigrid A1 - Walz, Ariane T1 - Detecting Himalayan glacial lake outburst floods from Landsat time series JF - Remote sensing of environment : an interdisciplinary journal N2 - Several thousands of moraine-dammed and supraglacial lakes spread over the Hindu Kush Himalayan (HKH) region, and some have grown rapidly in past decades due to glacier retreat. The sudden emptying of these lakes releases large volumes of water and sediment in destructive glacial lake outburst floods (GLOFs), one of the most publicised natural hazards to the rapidly growing Himalayan population. Despite the growing number and size of glacial lakes, the frequency of documented GLOFs is remarkably constant. We explore this possible reporting bias and offer a new processing chain for establishing a more complete Himalayan GLOF inventory. We make use of the full seasonal archive of Landsat images between 1988 and 2016, and track automatically where GLOFs left shrinking water bodies, and tails of sediment at high elevations. We trained a Random Forest classifier to generate fuzzy land cover maps for 2491 images, achieving overall accuracies of 91%. We developed a likelihood-based change point technique to estimate the timing of GLOFs at the pixel scale. Our method objectively detected ten out of eleven documented GLOFs, and another ten lakes that gave rise to previously unreported GLOFs. We thus nearly doubled the existing GLOF record for a study area covering similar to 10% of the HKH region. Remaining challenges for automatically detecting GLOFs include image insufficiently accurate co-registration, misclassifications in the land cover maps and image noise from clouds, shadows or ice. Yet our processing chain is robust and has the potential for being applied on the greater HKH and mountain ranges elsewhere, opening the door for objectively expanding the knowledge base on GLOF activity over the past three decades. KW - Random Forest KW - Fuzzy classification KW - Land cover maps KW - Change detection KW - Change points KW - Lakes KW - Sediment tails KW - Hindu Kush Himalayas (HKH) Y1 - 2018 U6 - https://doi.org/10.1016/j.rse.2017.12.025 SN - 0034-4257 SN - 1879-0704 VL - 207 SP - 84 EP - 97 PB - Elsevier CY - New York ER - TY - JOUR A1 - Ulloa, Hector A1 - Irourne, Andres A1 - Picco, Lorenzo A1 - Korup, Oliver A1 - Lenzi, Mario Aristide A1 - Mao, Luca A1 - Ravazzolo, Diego T1 - Massive biomass flushing despite modest channel response in the Rayas River following the 2008 eruption of Chaiten volcano, Chile JF - Geomorphology : an international journal on pure and applied geomorphology N2 - The 2008 eruption of Chaiten volcano in southern Chile severely impacted several densely forested river catchments by supplying excess pyroclastic sediment to the channel networks. Our aim is to substantiate whether and how channel geometry and forest stands changed in the Rayas River following the sudden input of pyroclastic sediment. We measured the resulting changes to channel geometry and riparian forest stands along 17.6 km of the impacted gravel-bed Rayas River (294 km(2)) from multiple high-resolution satellite images, aerial photographs, and fieldwork to quantify yield volume characteristics of the forest stands. Limited channel changes during the last 60 years before the eruption reflect a dynamic equilibrium condition of the river corridor, despite the high annual precipitation and the sediment supply from Chaiten and Michinmahuida volcanoes in the headwaters. Images taken in 1945, 2004, and 2005 show that total size of the vegetated channel islands nearly doubled between 1945 and 2004 and remained unchanged between 2004 and 2005. Pyroclastic sediment entering the Rayas River after the 2008 eruption caused only minor average channel widening (7%), but killed all island vegetation in the study reach. Substantial shifts in the size distribution of in-channel vegetation patches reflect losses in total island area of 46% from 2005 to 2009 and an additional 34% from 2009 to 2012. The estimated pulsed release of organic carbon into the channel, mainly in the form of large wood from obliterated island and floodplain forests, was 78-400 tC/km/y and surpasses most documented yields from small mountainous catchments with similar rainfall, forest cover, and disturbance history, while making up between 20% and 60% of the annual carbon burial rate of fluvial sediments in the northern Patagonian fjords. We conclude that the carbon footprint of the 2008 Chaiten eruption on the Rayas River was more significant than the measured geomorphic impacts on channel geometry for the first five years following disturbance. The modest post-eruptive geomorphic response in this river is a poor indicator of its biogeochemical response. (C) 2015 Elsevier B.V. All rights reserved. KW - Chaiten volcano KW - Forest disturbance KW - Channel island KW - Organic carbon Y1 - 2015 U6 - https://doi.org/10.1016/j.geomorph.2015.09.019 SN - 0169-555X SN - 1872-695X VL - 250 SP - 397 EP - 406 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Uhlmann, Manuela A1 - Korup, Oliver A1 - Huggel, Christian A1 - Fischer, Luzia A1 - Kargel, Jeffrey S. T1 - Supra-glacial deposition and flux of catastrophic rock-slope failure debris, south-central Alaska JF - Earth surface processes and landforms : the journal of the British Geomorphological Research Group N2 - The ongoing debate over the effects of global environmental change on Earth's cryosphere calls for detailed knowledge about process rates and their variability in cold environments. In this context, appraisals of the coupling between glacier dynamics and para-glacial erosion rates in tectonically active mountains remain rare. We contribute to filling this knowledge gap and present an unprecedented regional-scale inventory of supra-glacial sediment flux and hillslope erosion rates inferred from an analysis of 123 large (> 0 center dot 1km2) catastrophic bedrock landslides that fell onto glaciers in the Chugach Mountains, Alaska, as documented by satellite images obtained between 1972 to 2008. Assuming these supra-glacial landslide deposits to be passive strain markers we infer minimum decadal-scale sediment yields of 190 to 7400tkm-2yr-1 for a given glacier-surface cross-section impacted by episodic rock-slope failure. These rates compare to reported fluvial sediment yields in many mountain rivers, but are an order of magnitude below the extreme sediment yields measured at the snouts of Alaskan glaciers, indicating that the bulk of debris discharged derives from en-glacial, sub-glacial or ice-proximal sources. We estimate an average minimum para-glacial erosion rate by large, episodic rock-slope failures at 0 center dot 5-0 center dot 7mmyr-1 in the Chugach Mountains over a 50-yr period, with earthquakes likely being responsible for up to 73% of this rate. Though ranking amongst the highest decadal landslide erosion rates for this size of study area worldwide, our inferred rates of hillslope erosion in the Chugach Mountains remain an order of magnitude below the pace of extremely rapid glacial sediment export and glacio-isostatic surface uplift previously reported from the region. KW - glacier KW - landslide KW - erosion rate KW - sediment yield KW - Alaska Y1 - 2013 U6 - https://doi.org/10.1002/esp.3311 SN - 0197-9337 VL - 38 IS - 7 SP - 675 EP - 682 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Struck, Martin A1 - Andermann, Christoff A1 - Hovius, Niels A1 - Korup, Oliver A1 - Turowski, Jens M. A1 - Bista, Raj A1 - Pandit, Hari P. A1 - Dahal, Ranjan K. T1 - Monsoonal hillslope processes determine grain size-specific suspended sediment fluxes in a trans-Himalayan river JF - Geophysical research letters N2 - Sediments in rivers record the dynamics of erosion processes. While bulk sediment fluxes are easily and routinely obtained, sediment caliber remains underexplored when inferring erosion mechanisms. Yet sediment grain size distributions may be the key to discriminating their origin. We have studied grain size-specific suspended sediment fluxes in the Kali Gandaki, a major trans-Himalayan river. Two strategically located gauging stations enable tracing of sediment caliber on either side of the Himalayan orographic barrier. The data show that fine sediment input into the northern headwaters is persistent, while coarse sediment comes from the High Himalayas during the summer monsoon. A temporally matching landslide inventory similarly indicates the prominence of monsoon-driven hillslope mass wasting. Thus, mechanisms of sediment supply can leave strong traces in the fluvial caliber, which could project well beyond the mountain front and add to the variability of the sedimentary record of orogen erosion. KW - Himalayas KW - erosion KW - grain size KW - suspended sediments KW - landslide KW - river transport Y1 - 2015 U6 - https://doi.org/10.1002/2015GL063360 SN - 0094-8276 SN - 1944-8007 VL - 42 IS - 7 SP - 2302 EP - 2308 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Stolle, Amelie A1 - Schwanghart, Wolfgang A1 - Andermann, Christoff A1 - Bernhardt, Anne A1 - Fort, Monique A1 - Jansen, John D. A1 - Wittmann, Hella A1 - Merchel, Silke A1 - Rugel, Georg A1 - Adhikari, Basanta Raj A1 - Korup, Oliver T1 - Protracted river response to medieval earthquakes JF - Earth surface processes and landforms : the journal of the British Geomorphological Research Group N2 - Mountain rivers respond to strong earthquakes by rapidly aggrading to accommodate excess sediment delivered by co-seismic landslides. Detailed sediment budgets indicate that rivers need several years to decades to recover from seismic disturbances, depending on how recovery is defined. We examine three principal proxies of river recovery after earthquake-induced sediment pulses around Pokhara, Nepal's second largest city. Freshly exhumed cohorts of floodplain trees in growth position indicate rapid and pulsed sedimentation that formed a fan covering 150 km2 in a Lesser Himalayan basin with tens of metres of debris between the 11th and 15th centuries AD. Radiocarbon dates of buried trees are consistent with those of nearby valley deposits linked to major medieval earthquakes, such that we can estimate average rates of re-incision since. We combine high-resolution digital elevation data, geodetic field surveys, aerial photos, and dated tree trunks to reconstruct geomorphic marker surfaces. The volumes of sediment relative to these surfaces require average net sediment yields of up to 4200 t km–2 yr–1 for the 650 years since the last inferred earthquake-triggered sediment pulse. The lithological composition of channel bedload differs from that of local bedrock, confirming that rivers are still mostly evacuating medieval valley fills, locally incising at rates of up to 0.2 m yr–1. Pronounced knickpoints and epigenetic gorges at tributary junctions further illustrate the protracted fluvial response; only the distal portions of the earthquake-derived sediment wedges have been cut to near their base. Our results challenge the notion that mountain rivers recover speedily from earthquakes within years to decades. The valley fills around Pokhara show that even highly erosive Himalayan rivers may need more than several centuries to adjust to catastrophic perturbations. Our results motivate some rethinking of post-seismic hazard appraisals and infrastructural planning in active mountain regions. KW - fluvial response KW - sediment yield KW - earthquakes KW - Nepal KW - Himalaya Y1 - 2018 U6 - https://doi.org/10.1002/esp.4517 SN - 0197-9337 SN - 1096-9837 VL - 44 IS - 1 SP - 331 EP - 341 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Stolle, Amelie A1 - Langer, Maria A1 - Blöthe, Jan Henrik A1 - Korup, Oliver T1 - On predicting debris flows in arid mountain belts JF - Global and planetary change N2 - The use of topographic metrics for estimating the susceptibility to, and reconstructing the characteristics of, debris flows has a long research tradition, although largely devoted to humid mountainous terrain. The exceptional 2010 monsoonal rainstorms in the high-altitude mountain desert of Ladakh and Zanskar, NW India, were a painful reminder of how susceptible arid regions are to rainfall-triggered flash floods, landslides, and debris flows. The rainstorms of August 4-6 triggered numerous debris flows, killing 182 people, devastating 607 houses, and more than 10 bridges around Ladakh's capital of Leh. The lessons from this disaster motivated us to revisit methods of predicting (a) flow parameters such as peak discharge and maximum velocity from field and remote sensing data, and (b) the susceptibility to debris flows from catchment morphometry. We focus on quantifying uncertainties tied to these approaches. Comparison of high-resolution satellite images pre- and post-dating the 2010 rainstorm reveals the extent of damage and catastrophic channel widening. Computations based on these geomorphic markers indicate maximum flow velocities of 1.6-6.7 m s(-1) with runout of up to similar to 10 km on several alluvial fans that sustain most of the region's settlements. We estimate median peak discharges of 310-610 m(3) s(-1), which are largely consistent with previous estimates. Monte Carlo-based error propagation for a single given flow-reconstruction method returns a variance in discharge similar to one derived from juxtaposing several different flow reconstruction methods. We further compare discriminant analysis, classification tree modelling, and Bayesian logistic regression to predict debris-flow susceptibility from morphometric variables of 171 catchments in the Ladakh Range. These methods distinguish between fluvial and debris flow-prone catchments at similar success rates, but Bayesian logistic regression allows quantifying uncertainties and relationships between potential predictors. We conclude that, in order to be robust and reliable, morphometric reconstruction of debris-flow properties and susceptibility requires careful assessment and reporting of errors and uncertainties. (C) 2015 Elsevier B.V. All rights reserved. KW - debris flow KW - peak discharge KW - channel geometry KW - geomorphometry KW - Bayesian logistic regression KW - Transhimalaya Y1 - 2015 U6 - https://doi.org/10.1016/j.gloplacha.2014.12.005 SN - 0921-8181 SN - 1872-6364 VL - 126 SP - 1 EP - 13 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Stolle, Amelie A1 - Bernhardt, Anne A1 - Schwanghart, Wolfgang A1 - Hoelzmann, Philipp A1 - Adhikari, Basanta R. A1 - Fort, Monique A1 - Korup, Oliver T1 - Catastrophic valley fills record large Himalayan earthquakes, Pokhara, Nepal JF - Quaternary science reviews : the international multidisciplinary research and review journal KW - Catastrophic valley infill KW - Great Himalayan earthquakes KW - Radiocarbon age dating KW - Provenance analysis KW - Paleoseismology KW - Nepal Y1 - 2017 U6 - https://doi.org/10.1016/j.quascirev.2017.10.015 SN - 0277-3791 VL - 177 SP - 88 EP - 103 PB - Elsevier CY - Oxford 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 - 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 - Schwanghart, Wolfgang A1 - Worni, Raphael A1 - Huggel, Christian A1 - Stoffel, Markus A1 - Korup, Oliver T1 - Uncertainty in the Himalayan energy-water nexus: estimating regional exposure to glacial lake outburst floods JF - Environmental research letters N2 - Himalayan water resources attract a rapidly growing number of hydroelectric power projects (HPP) to satisfy Asia's soaring energy demands. Yet HPP operating or planned in steep, glacier-fed mountain rivers face hazards of glacial lake outburst floods (GLOFs) that can damage hydropower infrastructure, alter water and sediment yields, and compromise livelihoods downstream. Detailed appraisals of such GLOF hazards are limited to case studies, however, and a more comprehensive, systematic analysis remains elusive. To this end we estimate the regional exposure of 257 Himalayan HPP to GLOFs, using a flood-wave propagation model fed by Monte Carlo-derived outburst volumes of >2300 glacial lakes. We interpret the spread of thus modeled peak discharges as a predictive uncertainty that arises mainly from outburst volumes and dam-breach rates that are difficult to assess before dams fail. With 66% of sampled HPP are on potential GLOF tracks, up to one third of these HPP could experience GLOF discharges well above local design floods, as hydropower development continues to seek higher sites closer to glacial lakes. We compute that this systematic push of HPP into headwaters effectively doubles the uncertainty about GLOF peak discharge in these locations. Peak discharges farther downstream, in contrast, are easier to predict because GLOF waves attenuate rapidly. Considering this systematic pattern of regional GLOF exposure might aid the site selection of future Himalayan HPP. Our method can augment, and help to regularly update, current hazard assessments, given that global warming is likely changing the number and size of Himalayan meltwater lakes. KW - hydropower KW - water resources KW - glacial hazards KW - glacial lake outburst floods KW - Himalayas Y1 - 2016 U6 - https://doi.org/10.1088/1748-9326/11/7/074005 SN - 1748-9326 VL - 11 PB - IOP Publ. Ltd. CY - Bristol ER -