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Ocena aktywności wybranych osuwisk w rejonie Jeziora Rożnowskiego w świetle badań terenu

Wódka Marcin

Przegląd Geologiczny

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2020

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Vol. 68, nr 1

60--68

EN

The article compares results of field assessment of activity of selected landslides in the Rożnowskie Lake region, obtained in 2010-2014 with a differential digital models (DDM) from airborne laser scanning data of 2010, 2013 and 2018. Results of DDM analyses were similar to those from field studies. The most difficult task in the field research was to distinguish between active landslides, where the last movements took place over three years after the date of landslide registration, and periodically active landslides, the last visible movements that took place five years ago. The article underlines that not all displacements within the landslides, visible on differential terrain models, are the result of colluvium landslide movement. Sometimes they are due to anthropogenic activities. Differential digital model in the Znamirowice landslide presents terrain changes that have resulted from intensive agricultural land use.

2

Assessment of landslide hazard from tree-ring eccentricity and from compression wood : a comparison

Łuszczyńska Katarzyna, Malik Ireneusz, Wistuba Małgorzata, Krąpiec Marek

Geological Quarterly

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2019

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Vol. 63, No. 2

296--301

EN

We have compared maps of landslide activity and hazard, developed with the use of two different dendrochronological indicators: tree-ring eccentricity and reaction (compression) wood. The maps were prepared based on 125 Norway spruce (Picea abies L. Karst.) trees growing at 44 sampling points, distributed over an area of 3.75 km2. In general, the two maps show similar patterns of landslide activity. However, tree-ring eccentricity yielded a greater number of dated events (246) compared to compression wood (129). Besides the differences in the absolute values of dating results, the general landslide activity and hazard zonation based on both disturbances are similar. Both growth disturbances develop as a result of stem tilting. Eccentricity develops after slight tilting, while compression wood is developed when tilting is more significant. Because of the differences in the strength of disturbing factors, which cause the development of compression wood and growth eccentricity, the best approach would be to combine the results of dating obtained from the two methods. The dendrochronological analysis of tree growth disturbances (eccentric growth and compression wood) is a promising approach for determining landslide hazards in forested mountain areas and can be applied in spatial management.

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Dendrochronological dating as the basis for developing a landslide hazard map – An example from the Western Carpathians, Poland

Łuszczyńska K., Wistuba M., Malik I., Krąpiec M., Szypuła B.

Geochronometria

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2018

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Vol. 45, no. 1

173--184

EN

Most landslide hazard maps are developed on the basis of an area’s susceptibility to a landslide occurrence, but dendrochronological techniques allows one to develop maps based on past landslide activity. The aim of the study was to use dendrochronological techniques to develop a landslide hazard map for a large area, covering 3.75 km2. We collected cores from 131 trees growing on 46 sampling sites, measured tree-ring width, and dated growth eccentricity events (which occur when tree rings of different widths are formed on opposite sides of a trunk), recording the landslide events which had occurred over the previous several dozen years. Then, the number of landslide events per decade was calculated at every sampling site. We interpolated the values obtained, added layers with houses and roads, and developed a landslide hazard map. The map highlights areas which are potentially safe for existing buildings, roads and future development. The main advantage of a landslide hazard map developed on the basis of dendrochronological data is the possibility of acquiring long series of data on landslide activity over large areas at a relatively low cost. The main disadvantage is that the results obtained relate to the measurement of anatomical changes and the macroscopic characteristics of the ring structure occurring in the wood of tilted trees, and these factors merely provide indirect information about the time of the landslide event occurrence.

4

Dendrochronological study of the Sawicki landslide activity in the Beskid Niski Mts (Polish Flysch Carpathians)

Kiszka K.

Landform Analysis

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2016

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Vol. 32

9--26

EN

The article presents the results of the dendrogeomorphological study of the activity of the Sawicki landslide, located in the Beskid Niski Mts (Polish Flysch Carpathians). The study was conducted within two study sites in the lower part of the landslide. The landslide movements were dated using the dendrogeomorphological method, basing on the eccentricity indicators calculated for the two coniferous species, i.e. Scots pine (Pinus sylvestris) and silver fir (Abies alba). It was found landslide activity in years: 1899, 1901, 1905, 1910, 1913–1914, 1920–1921, 1929–1931, 1935, 1937, 1945, 1977, 1979, 1981, 1984–1985, 1990, 1992–1993, 1997, 2003–2004, 2006, 2010–2012. The greatest activity was characterized for the northern part of the study site B and the south-western slopes of the Szklarki stream valley (study site A). Studies have shown only a partial dependence between precipitation and landslide episodes. The data were confronted with the results of dendrogeomorphological studies, conducted in the northern and central parts of the landslide. The results demonstrate the significant complexity of mass movements within large-area landslide.

5

Low magnitude earthquakes and landslide activity: a case study from Italy

Lamanna C., Del Gaudio V., Wasowski J.

Polish Geological Institute Special Papers

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2005

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Vol. 20

76--85

EN

We report on a slump-earth flow occurred in Southern Apennines following a 3-day rainstorm in late 1993. Subsequently, the landslide underwent different phases of activity, and in particular, the reactivation phase in 1995, which apparently coincided with a series of minor earthquakes (local magnitude ~ 3) and seasonal rainfall events. We focus on one and a half year temporal-spatial variations in retrogressive evolution of the landslide and attempt to identify cause-effect relations between the main scarp failures and the occurrence of seismic and rainfall events. For this purpose, qualitative and quantitative correlations are sought between possible causative factors and landslide activity. The results show that: (1) the general retrogressive trend is neither directly correlated to the temporal seismic activity pattern, nor to the monthly or short term precipitation; instead, the trend appears to be influenced by groundwater level variations, which are related to a few month cumulative precipitation pattern; (2) the variations in retrogressive activity of the main scarp, with respect to the general trend, show a limited positive correlation with seismic energy and monthly precipitation pattern; (3) the relative influence of precipitation appears to be greater than that of seismic activity; the latter seems to give a contribution to instability only when the main scarp is already unstable. These results indicate that, in presence of other causative factors, low energy seismic activity can have a complementary role as destabilising agent; however, a rigorous quantification of its relative weight would require more detailed and longer term monitoring data provided by continuous in situ recording instrumentation.

PL

W artykule przedstawiono duży spływ ziemny w południowych Apeninach, który nastąpił pod koniec 1993 roku, po trzydniowym sztormie. Osuwisko przeszło następnie rozmaite fazy aktywności, a zwłaszcza fazę odnowienia w 1995 roku, powiązaną z serią niewielkich trzęsień ziemi o nasileniu ~3 oraz z okresowymi opadami. Zwrócono uwagę na półtoraroczne zmiany przestrzenne w ewolucji osuwiska oraz na próbę określenia związku przyczynowo-skutkowego pomiędzy podcięciem skarpy oraz wystąpieniem zjawisk sejsmicznych i opadów. W tym celu przebadano jakościowe i ilościowe związki pomiędzy prawdopodobnymi przyczynami a aktywnością osuwiska. Otrzymano następujące wyniki: (1) rozwój nie jest związany bezpośrednio z okresową aktywnością sejsmiczną ani z opadami miesięcznymi lub krótkotrwałymi, natomiast prawdopodobnie jest związany ze zmianami poziomu wód gruntowych powodowanych kumulacją kilkumiesięcznych opadów; (2) zmiany ogólnego trendu zachowania się głównej skarpy wykazują związek z aktywnością sejsmiczną oraz z rozkładem miesięcznych opadów; (3) względny wpływ opadów wydaje się być większy od aktywności sejsmicznej, jakkolwiek ta ostatnia ma swój wkład w dalszą destabilizację już naruszonej skarpy. Wyniki te wskazują, że słabe wstrząsy sejsmiczne osłabiają stabilność stoków poddanych innym poważniejszym czynnikom. Dokładniejsze określenie tych relacji będzie jednak wymagać bardziej długotrwałych i dokładniejszych obserwacji przy użyciu instrumentów prowadzących zapisy na miejscu.