publications

2024

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

   Tomáš Pánek, Michal Břežný, Hans-Balder Havenith, and 1 more author

   Geomorphology, Mar 2024

   Abs

   Active fold-and-thrust belts create new landslide-prone slopes during tectonic deformation propagation. How­ ever, studies on landslide distribution in newly formed fold-and-thrust belts are limited. In this study, we present a new inventory of landslides in the Kura fold-and-thrust belt, a tectonically active, but relatively low-altitude southern margin of the Greater Caucasus. The area has been tectonically framed in the last ~2–3 Ma and is represented by folds and thrusts deforming Miocene to Quaternary sediments. Through satellite imagery anal­ ysis, we mapped nearly 1600 landslides, with a quarter currently active. While landslides cover \textless1 % of the area, they tend to cluster at higher elevations and in regions with relatively high local relief. Landslides predominantly occur in tectonically uplifted areas, affecting the highest and steepest parts of growing anticlines and the steep slopes of incising valleys intersecting active thrust faults. Based on observed landslide distribution in folds at different stages of development, we propose a conceptual model for the temporal evolution of landslide patterns in weak sediment-based fold-and-thrust belts: 1) In the initial stages, slow-moving slope deformations affect incipient thrust fronts. With the flanks of the growing anticline lacking sufficient steepness, landslides tend to concentrate in deep valleys intersecting the uplifting hanging walls. 2) With ongoing thrust uplift, growing and steepening anticlines become more prone to planar sliding when dip slopes exceed friction angle, and valley development creates additional dip slopes, resulting in widespread landslides. 3) In the final stage, erosional decay reduces topographic relief, leading to badland formation with gully erosion and decreased landslide occurrence.

2. Accelerated retreat of northern James Ross Island ice streams (Antarctic Peninsula) in the Early-Middle Holocene induced by buoyancy response to postglacial sea level rise

   Matěj Roman, Daniel Nývlt, Bethan J. Davies, and 7 more authors

   Earth and Planetary Science Letters, Sep 2024

   Abs

   The knowledge of dynamics and retreat patterns of marine-based ice streams under multiple stressors are of foremost importance for predicting Antarctic Ice Sheet response to climate changes. The Holocene palaeoglaciological record of former ice streams draining the northeast Antarctic Peninsula can elucidate the influences of changes in atmospheric and oceanic circulation and sea-level oscillations on the ice thinning and grounding line retreat. Here, terrestrial cosmogenic nuclide (TCN) dating of erratic boulders across the James Ross Island group sheds light on the pattern and timing of the ice recession along the two main arteries of the palaeo-ice drainage: Croft Trough and Prince Gustav Channel. The approach of using paired 10Be-26Al nuclides enabled an assessment of cosmogenic isotope inheritance and complex burial-exposure history, notably on the high-altitude volcanic mesas. The TCN ages suggest that the Prince Gustav Channel Ice Stream was thinning from at least ∼12 ka, with subsequent separation of the Antarctic Peninsula and James Ross Island ice masses by 10–8 ka. The transition from grounded ice to open marine conditions in the Croft Trough occurred rapidly at 8.6–7.2 ka, following the Early Holocene Warm Period, concomitant with eustatic and relative sea-level rise and incursions of warmer circumpolar waters. Grounding line retreat was possibly further accelerated by buoyancy response of thinning ice stream to low-gradient bed topography. The lessons of rapid deglaciation of James Ross Island palaeo-ice streams may provide analogues for recent or future intensification of pressures on Antarctic glaciers.

2023

1. The largest rock avalanches in Patagonia: Timing and relation to Patagonian Ice Sheet retreat

   Tomáš Pánek, Michal Břežný, Rachel Smedley, and 4 more authors

   Quaternary Science Reviews, Feb 2023

   Abs

   One of the largest concentrations of giant landslides (≥108 m3) in Patagonia is in the eastern part of Lago Cochrane/Pueyrredón (LP) valley in Argentina. In addition to minor earthflows and rock slides, this landslide cluster is dominated by rock and debris avalanches that affect the northern slope of Meseta Belgrano, the largest of which have volumes \textgreater1 km3 and a runout of \textgreater10 km. To determine the chronology of these large landslides and their relationship to the geological setting and the glacial history related to the Last Glacial Maximum (LGM) ∼20–18 ka ago, we combined geomorphological mapping with absolute dating (luminescence and radiocarbon dating) and numerical modelling of slope stability. Dating and cross-cutting relationships with glaciolacustrine deposits suggest that some of the largest rock avalanches collapsed directly into a glacial lake between ∼17 and ∼12 ka, soon after deglaciation, but some were pre-glacial and landslide activity continued until today, posing a potential hazard to the area. In agreement with these data, numerical modelling suggests that slope stability was only marginally affected by ice retreat and glacial lake drainage, and landslides were most likely favoured by relatively low rock strength, related glacially-conditioned topography, and, possibly, seismic activity. A newly identified active fault at the base of the Meseta Belgrano, whose activity was likely enhanced by postglacial rebound, was probably the key factor that concentrated postglacial rock avalanches into the LP valley. We conclude that exceptionally large (km-scale) landslides can occur on slopes made of relatively weak rocks in a glacially-conditioned topographic setting even without a strong direct triggering effect of deglaciation, while fatigue due to long-term seismicity may promote collapse.

2022

1. Large landslides cluster at the margin of a deglaciated mountain belt

   Tomáš Pánek, Michal Břežný, Stephan Harrison, and 2 more authors

   Scientific Reports, Apr 2022

   Number: 1 Publisher: Nature Publishing Group

   Abs

   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 (\textgreater 0.9 km2) over an unprecedentedly large area of Southern Patagonia (~ 305,000 km2), 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.

2021

1. Complex causes of landslides after ice sheet retreat: Post-LGM mass movements in the Northern Patagonian Icefield region

   Tomáš Pánek, Michal Břežný, Jakub Kilnar, and 1 more author

   Science of The Total Environment, Mar 2021

   Abs

   Although the dynamics of individual rock-slope failures above recently shrinking glaciers have received increasing study, less is known about the spatial distribution of landslides in paraglacial settings. Here, we present a landslide inventory for large deglaciated area (~100,000 km2) situated within the Last Glacial Maximum (LGM) limits of the Northern Patagonian Icefield (NPI). Using satellite images and the TanDEM-X digital elevation model, we mapped a total of 15,543 landslides, among which 1006 are deep-seated landslides (DSLs) with area ≥0.01 km2. The distribution of DSLs is highly asymmetric in a W-E transect of the NPI region, with pronounced clustering along the semi-arid eastern front of the Patagonian Andes. The most strongly affected domain is volcanic tablelands overlying weak Miocene sedimentary rocks, but DSLs tend to also cluster along recently deglaciated (i.e. since the end of the 19th century) eastern margin of the NPI. Compared with other high mountain regions, alpine valleys of the Patagonian Andes are affected by DSLs only in \textless1% of their area, an order of magnitude lower than in other reported deglaciated mountains. The modest incidence of DSLs in the Patagonian Andes is due to dominance of hard granitoid rocks and relatively weak historical seismic activity. We conclude that 1) geological conditions control the distribution of DSLs and their types in the NPI region; 2) paraglacial effects play secondary (although locally important) roles in the origin of DSLs; 3) local clusters of large DSLs originate due to specifics of the post-LGM landscape evolution, involving drawdowns of glacial lakes and incision of rivers into the unconsolidated deposits; and 4) increased abundance of landslides above the recently shrinking margin of the NPI results from the repeated Holocene fluctuations of glacier snouts around the Little Ice Age (LIA) glacier limits and the spatial coincidence of glacial debuttressing effects with the presence of active faults.

2. Old but still active: \textgreater 18 ka history of rock slope failures affecting a flysch anticline

   Michal Břežný, Tomáš Pánek, Règis Braucher, and 5 more authors

   Landslides, Jan 2021

   Abs

   The Czech part of the Outer Western Carpathians (COWC) formed by flysch rocks is among the most landslide-prone areas in Europe. Recent LiDAR-based inventory mapping reveals that the area of the COWC encompasses more than 13,500 landslides, with some geological domains exhibiting \textgreater 20% of the surface area covered by landslides. Although mass movements represent crucial geomorphic agents in the COWC, their timing and especially lifespan remain elusive. In this study, we focused on rockslides affecting the flanks of the flysch anticline developed within Paleogene sandstones. The area (“Hradisko” ridge) is well known as the most extensive rock city in the COWC. Structural-geological investigation, kinematic analysis and the application of near-surface geophysics (ERT, GPR and seismic refraction) suggest that rockslides accompanied by toppling and lateral spreads are predisposed by the architecture of bedding planes, joints and inherited faults cross-cutting the anticlinal ridge. Based on 10Be exposure dating of five scarps and rockslide boulders (a total of 25 cosmogenic-dated samples), we were able to reconstruct the long-term history of rock slope failures. Although the obtained ages of headscarp exposures reveal consistent patterns suggesting major mass movement phases at ~ 18 ka and ~ 12 ka, the interpretation of boulder exposure ages is ambiguous. The study area has not been affected by catastrophic slope failure in historic times, but dendrogeomorphic analysis reveals surprisingly strong tree ring signals of mass movements within the last 150 years. These findings suggest that progressive failure is developing within some parts of the rockslide and/or slope portions above the major scarp. We conclude the following: (1) some rockslide spots within the COWC might express a very long history, encompassing the full Late Glacial–Holocene Period; (2) major mass movement activity in the study site temporally coincided with the major climatic changes; (3) rockslides with a very long history still represent potential hazards, although evidence of their active movement is not detected by standard geomorphic mapping techniques and (4) dating of the scarps should be preferred as even a higher number of boulders might be unreliable.

3. Low-topography deep-seated gravitational slope deformation: Slope instability of flysch thrust fronts (Outer Western Carpathians)

   Vladimír Chalupa, Tomáš Pánek, Karel Šilhán, and 3 more authors

   Geomorphology, Sep 2021

   Abs

   Unlike high-relief mountain areas, low-relief hilly landscapes are usually rarely affected by deep-seated gravitational slope deformations (DSGSDs). However, low-topography flysch thrust fronts can create suitable structural conditions for DSGSDs. The study area of the Kavalčanky ridge represents a relatively low-lying (\textless120 m of local relief) DSGSD-affected ridge situated at the thrust front in the flysch Outer Western Carpathians (Czech Republic). With the aim of revealing the main controlling factors and temporal constraints of mass-movement activity, a multidisciplinary investigation of DSGSDs was performed. Typical DSGSD landforms were mapped using high-resolution LiDAR-based mapping. Structural analysis revealed the presence of specific flysch thrust structural conditions with competent sandstone units overthrusted on a weak tectonically disrupted claystone basement. Geophysical measurement with the use of electrical resistivity tomography (ERT) and ground penetrating radar (GPR) profiling confirmed the deep reach (\textgreater50 m) of the studied DSGSD. Together with slope stability finite element modelling, geophysics suggests that the shear zone of DSGSDs is represented by one of the thrust faults, whereas lateral limits are formed by a set of conjugate strike-slip faults. Radiocarbon dating of bogs within the DSGSD body showed two phases of mass-movement activity corresponding to the Late Glacial-Holocene transition and Middle Holocene. The recent activity was excluded by dendrogeomorphic analysis. We concluded that the structural conditions involving high lithological complexity, tectonic weakening and the presence of major tectonic contacts might create conditions prone to DSGSDs even in relatively low-topography settings with mass movement activity, especially during humid and warmer Late Quaternary periods.

2020

1. Post-LGM faulting in Central Europe: LiDAR detection of the \textgreater50 km-long Sub-Tatra fault, Western Carpathians

   Tomáš Pánek, Jozef Minár, Ladislav Vitovič, and 1 more author

   Geomorphology, Sep 2020

   Abs

   The increasing availability of high-resolution LiDAR data reveals surprisingly strong topographic evidence of late Quaternary faulting in some intraplate regions characterized by weak recent tectonic activity. For the first time, we present evidence of a N50 km-long post-Last Glacial Maximum (LGM) tectonic rupture along the southern margin of the Tatra Mountains (Slovakia) in the highest part of the Carpathian Mountains. Using a highresolution 1 × 1 m LiDAR DEM, we recognize that the normal, range-bounding Sub-Tatra fault (STF) and its eastward branch, the Ružbachy fault (RBF), offset late Quaternary glacial moraines, alluvial fans and colluvial slopes. The fault zone morphology is dominated by a nearly continuous, southward-facing, up to ~18 m-high main scarp locally accompanied by antithetic fault scarps and hanging wall grabens. Similar offsets of pre-LGM and LGM deposits and the absence of fault scarps within Holocene alluvium suggest that the STF and RBF were active for a relatively short time interval between ~18 ka and the Holocene. Using the vertical separation of dated LGM moraine crests, we estimate that the minimum average postglacial slip rates along the STF and RBF varied from ~0.1–0.3 mm/year, i.e., rates one order of magnitude higher than those reported for other faults in Central Europe. Additionally, deep-seated landslides and the presence of large rock avalanches along the fault suggest possible postglacial high-magnitude earthquake(s) producing coseismic rupture of the STF and RBF. We conclude that 1) southern range-bounding faults of the Tatra Mountains are the longest (N50 km) and only documented post-LGM ruptures revealing extensive offset of late Quaternary deposits in the Western Carpathians and 2) relatively small along-strike variations in postglacial offset mimic the long-term exhumation trends and imply “en block” uplift of the southern margin of the Tatra Mountains with the highest displacement along the east STF.

2. Moraines and marls: Giant landslides of the Lago Pueyrredón valley in Patagonia, Argentina

   Tomáš Pánek, Elisabeth Schönfeldt, Diego Winocur, and 4 more authors

   Quaternary Science Reviews, Nov 2020

   Abs

   Giant catastrophic landslides (\textgreater108 m3) dot the formerly glaciated mountain forelands of the eastern Patagonian Andes. From geomorphic mapping, sedimentological logs and radiocarbon dating, we infer the emplacement kinematics and approximate timing of giant landslides in moraines and other glacial deposits in the Lago Pueyrredo n valley (LPV), Argentina. For the first time, we report in detail examples of giant low-gradient landslides with hummocky lobes derived from unconsolidated glacial deposits and weak bedrock. We find that at least 4.5 km3 of debris and weak bedrock were mobilized by slope failures in an area of ~500 km2 since the Last Glacial Maximum (LGM; ~25e18 ka). Nearly 90% of this landslide volume originated along the shores of, or as subaqueous failures in, a postglacial moraine-dammed meltwater lake. The larger landslides (\textgreater1 km3) detached from moraines fringing the lake, whereas other landslides displaced glacial and lake deposits either on the paleolake bed, or in a river gorge that was cut upon drainage of the glacial lake. Sequences of till, glaciofluvial and glaciolacustrine deposits overlying weak Early Miocene marlstone are mostly conducive to major landslides in the LPV. Crosscutting relationships indicate that largest landslides in the area originated during rapid glacial lakelevel drops. Distribution and internal structure of hummocks within landslide lobes suggest that these landslides were emplaced as catastrophic debris avalanches. It suggests that giant catastrophic landslides in the glacier forelands of Patagonia can result from layered weak rocks, changes in meltwater-lake levels, and possibly as a consequence of strong earthquakes linked to rapid post-glacial rebound following the retreat of the Patagonian Ice Sheet (PIS).

2019

1. Large landslides and deep-seated gravitational slope deformations in the Czech Flysch Carpathians: New LiDAR-based inventory

   Tomáš Pánek, Michal Břežný, Veronika Kapustová, and 2 more authors

   Geomorphology, Dec 2019

   Abs

   Moderate-relief landscapes, such as the Czech Flysch Outer Western Carpathians (COWC), in comparison with alpine regions are rarely subject to extensive landslide inventory mapping. An understanding of landslides in such a landscape is needed, because densely populated hilly landscapes in temperate zones are usually of major socio-economic importance. In this study, we performed the first LiDAR-based landslide mapping for the entire COWC area (~7539 km2), one of the most landslide-prone regions in Europe. By calculating various landscape and landslide metrics, we infer the distribution, frequency-area relationships, kinematics and controls of mass movements with special attention on large landslides (≥0.1 km2) and deep-seated gravitational slope deformations (DSGSDs). We mapped a total of 13,611 landslides, of which 1357 failures are large landslides and DSGSDs. Whereas the lower and more subdued areas in the southern part of COWC are hotspots in terms of the total number of landslides, the higher and more topographically pronounced areas in the northeast are affected predominantly by large landslides and DSGSDs. However, landslides with ≥0.1 km2 are widespread throughout the whole territory of COWC. A discrepancy also exists in the spatial distribution of different types of landslides. Rock slides and DSGSDs are dominant in the north-east, while flow-type landslides are dominant in the southern lower topographic relief with claystone-dominated flysch. We conclude that 1) distinct geological units (nappes) produce landslide populations with different frequency-area distributions; 2) stratigraphic composition alongside the tectonic style of flysch formations control the type of landslides; 3) DSGSDs affect mainly slopes formed by rigid rocks sitting atop soft formations; and 4) geological conditions, rather than topography, control distribution of large landslides and DSGSDs in COWC.

2018

1. Giant landslides in the foreland of the Patagonian Ice Sheet

   Tomáš Pánek, Oliver Korup, Jan Lenart, and 2 more authors

   Quaternary Science Reviews, Aug 2018

   Abs

   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 Puyerredo n 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 rivergorge 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 \textgreater60% of the landslide volume (~96 km3) detached after the Last Glacial Maximum (LGM). Giant slope failures crosscutting 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.

2. Sackung and enigmatic mass movement folds on a structurally-controlled mountain ridge

   Michal Břežný, Tomáš Pánek, Jan Lenart, and 3 more authors

   Geomorphology, Dec 2018

   Abs

   The recently emerged concept of “slope tectonics” suggests that mass movement processes can produce structures similar in morphological expression to that of extensional, strike-slip and compressional tectonic deformations. Further, there has long been debate about the (tectonic or gravitational) origin of lineaments found on hillslopes. Here we present cases of where geological structure and inherited tectonic structures have preconditioned the development of mass movements and creation of slope tectonic features on a monoclinal ridge (Smrk Mt.) in the Outer Western Carpathians, Czechia. Geomorphic mapping from LiDAR-derived topography, structural measurements, electrical resistivity tomography and ground penetrating radar, were used to map synthetic and antithetic scarps, thrusts, and folds, and assess their relation to geological and tectonic structures. The scarps are found to be strongly related to transverse (NNW to NNE trending) inherited normal and strike-slip faults and mainly cross-cut the topography of the mountain ridge. Some of the folds are thought to have originated from buckling or compression in the distal parts of landslides. In other places, transpressional folds have developed oblique to major lateral shear surfaces interpreted to be sackung (mass movement scarps) that have been inherited from tectonic faults. The transpressional folds developed due to localized contraction along bends in the lateral shear surface as mass movement proceeded. Ramp-flat thrust folds developed in the compressional parts of landslides, where the landslide intersects with slope parallel sackung and/or inherited fault planes inclined to the slope. Altogether, this study demonstrates a connection between kinematics of deep-seated gravitational slope deformations (DSGSDs), shallower landslides and the origin of transpressive, ramp-flat thrust, and detachment structures in rock slopes.

3. 10Be dating reveals pronounced Mid-to Late Holocene activity of deep-seated landslides in the highest part of the Czech Flysch Carpathians

   Michal Břežný, Tomáš Pánek, Jan Lenart, and 2 more authors

   Quaternary Science Reviews, Sep 2018

   Abs

   Although the highest part of the Czech Outer Western Carpathians lacks significant recent landslide activity, the vast area (~20%) of their territory is occupied by relict deep-seated landslides and deepseated gravitational slope deformations. Dating these deformations might help to determine degrees of present-day landslide hazard in that area. Based on the 10Be exposure dating of eight rocky scarps and walls of ridge-top trenches, we estimated the minimal ages of the deep-seated landslides (DSLs) and one deep-seated gravitational slope deformation (DSGSD) in the Satina River basin in the Moravskoslezske Beskydy Mts. The obtained ages (~9.7e2.9 ka) suggest Holocene slope instability in the area with a pronounced cluster of ages spanning from ~6.0 to 2.9 ka. Except for one DSL, the ages reveal rather episodic activity of gravitational movements. Mid-to early Late Holocene activity of large landslides in the study area corresponds to the ages of several previously dated landslides both in an adjacent region as well as within the Central European context. With respect to the historical quiescence of the DSLs and DSGSDs in the area and because the slopes have not been destabilized, even during the most extreme hydrometeorological events within the last few decades, we infer that the hydrometeorological thresholds necessary for their activation are seldom exceeded in this area. Therefore, the highest parts of the Carpathians built by rigid thick-bedded lithology reveal a rather lower frequency of events in comparison with adjacent parts formed by claystone-dominated flysch, where several large DSLs originated in the last few decades as a consequence of heavy rainfalls.

4. Increased gully activity induced by short-term human interventions – Dendrogeomorphic research based on exposed tree roots

   Radek Tichavský, Olga Kluzová, Michal Břežný, and 4 more authors

   Applied Geography, Sep 2018

   Abs

   The recent acceleration of gully erosion caused by environmental factors and human impacts has led to an enhanced demand for applied research in risk-prone areas worldwide. We investigated the dynamics of gullies that have recently threatened dwellings and railways in the foreland of the Eastern Sudetes (340–390 m a.s.l. in the NE part of Czechia). Flood countermeasures in a residential area above the study site created conditions conducive to accelerated erosion in the gullies; thus, the main aim of this study was to determine how human interventions changed the spatio-temporal dynamics of the gullies during a short period. Twenty two gullies (with a mean length 48.5 m) have developed on a 1-km-wide escarpment (with a mean slope 25°) composed of glaciogenic sediments of various sizes. Dendrogeomorphic techniques were applied on 23 exposed roots of Tilia cordata Mill. (a tree species that has never been used to detect root exposure). Microsections were prepared using a G.S.L.1 sledge microtome and analysed using the WinCELL Reg software to determine the timing of root exposure.

5. Regional, tree-ring based chronology of landslides in the Outer Western Carpathians

   Karel Šilhán, Radek Tichavský, Václav Škarpich, and 2 more authors

   Geomorphology, Nov 2018

   Abs

   Landslides are a type of mass wasting and denote any downslope movement of soil and rock under the influence of gravity; as such they can represent a dangerous natural hazard process, especially in case that they affect inhabited areas or transport infrastructure. Because the occurrence of landslides is typically favoured by terrain and lithological conditions, the process is frequently concentrated in relatively small, isolated regions exhibiting suitable initial conditions of terrain instability. Extensive regional assessments of landslide activity have been used in the past to uncover common triggers and process patterns, mostly in the aftermath of large, regional disasters. By contrast, however, regional reconstructions of past landslide activity have not been realized with dendrogeomorphic techniques, and with the aim to date past landslide histories over extended time periods and with annual dating precision. This study therefore aims at disentangling landslide dynamics at the regional scale (covering ca. 600 km2) by using growth-ring records of trees that grow on active landslides. The studied area of the Hostýnsko-vsetínská hornatina Mts. (Central Europe) is well known for its high landslide activity, but has so far been lacking a detailed chronology of past events. To this end, we dated past activity on 26 landslide bodies using tree-ring series from 1322 disturbed trees to reconstruct 327 landslide reactivations during the last century.

2017

1. Deep-seated landslides affecting monoclinal flysch morphostructure: Evaluation of LiDAR-derived topography of the highest range of the Czech Carpathians

   Michal Břežný, and Tomáš Pánek

   Geomorphology, May 2017

   Abs

   The recent launch of national-scale LiDAR-derived topographic data provides an opportunity for (re)evaluating the geomorphic imprint of landslides in forested mountains. A LiDAR-based inventory of deep-seated landslides (DSLs) in the highest part of Czech Outer Western Carpathians (Moravskoslezské Beskydy Mts.) reveals that nearly 20% of the territory is affected by ancient DSLs. Rather than the topography itself, we show that the geological characteristics of flysch rocks control the density, scaling relationships and morphometry of DSLs. They reveal a strong tendency to clustering in areas with favourable structural conditions, such as cataclinal slopes of individual monoclinal ridges formed by thick-bedded sandstones. In comparison with high-mountain areas and regions dominated by weaker lithology (e.g., claystone-dominated flysch), sandstone-dominated monoclinal structure of the Moravskoslezské Beskydy Mts. features predominantly short-travelled DSLs that are arrested on slopes and thus reveal a higher slope gradient than non-landslide terrain. Finally, we propose a conceptual model for the evolution of DSLs on monoclinal flysch morphostructures, particularly where coherent sandstone caps overlie weak claystone/siltstone-dominated flysch. In these conditions, we distinguish between “low” and “high” monoclinal ridges, where the former is capped by relatively thin sandstones overlying claystone formations and sandstones predominate in the structure of the latter. We show that the density of DSLs on the cataclinal/dip slopes is similar on both types of monoclinal ridges, but that major differences exist in the evolution of anaclinal/escarpment slopes. Here, low monoclinal ridges are highly affected by DSLs, but escarpments of high monoclinal ridges are nearly devoid of any DSLs.

2016

1. Cosmogenic age constraints on post-LGM catastrophic rock slope failures in the Tatra Mountains (Western Carpathians)

   Tomáš Pánek, Zbyněk Engel, Pavel Mentlík, and 4 more authors

   CATENA, Mar 2016

   Abs

   Although deglaciation is one of the crucial factors controlling the stability of slopes in high mountains, the chronological response of rock slope failure (RSF) to glacier retreat still remains poorly known. Here we provide the first cosmogenic (10Be) age constraints on prominent rock avalanches and rockfalls (collectively termed ‘rock slope failures’ – RSFs) from the Tatra Mountains, the highest mountain range with the most pronounced glacier morphology within the Carpathians. Six representative RSFs were selected for surface exposure dating in the mountain range. Two sites are situated in the western part with less pronounced local relief and gentler slope gradient, and four come from the highest eastern part with oversteepened rock slopes. Our dataset also contains the largest known RSF in the Tatra Mountains; the Koprová rock avalanche with a volume of ~5.4 × 106 m3. Based on 26 10Be dated boulders, the weighted mean ages of individual RSF accumulations range between 20.2 ± 1.2 and 10.1 ± 0.3 ka. Our results suggest that smaller, structurally predisposed failures (mainly rockfalls) in the steepest parts of the mountains reacted immediately (i.e. a few hundred years) to deglaciation, whereas more complex slope deformations in terrain with lower local relief, involving the largest rock avalanche in the Tatra Mountains, experienced a substantial time lag (i.e. several millennia) in respect to ice retreat. In the case of delayed RSFs, their origin can be well correlated with warmer and more humid periods in the Lateglacial/early Holocene such as the Bølling–Allerød chronozone and after the onset of the Holocene.

2015

1. Sesuvy: hrozba i krása

   Michal Břežný

   Geografické rozhledy, Mar 2015

2013

1. New methods to reconstruct clast transport history in different glacial sedimentary environments: Case study for Old Red sandstone clasts from polythermal Hørbyebreen and Bertilbreen valley glaciers, Central Svalbard

   Martin Hanáček, Daniel Nývlt, Jan Flašar, and 8 more authors

   Czech Polar Reports, Mar 2013