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The deformation characteristics and instability patterns of rotational landslides are complicated. Such landslides are large and occur continuously, seriously threatening people's lives. We used interferometry synthetic aperture radar (InSAR), digital elevation models of difference (DODs), numerical simulations, and other techniques for analyzing the topographic changes, surface deformation and movement process before, during and after a landslide. Based on the high-resolution terrain data before and after the landslide, the topographic changes were analyzed, and the active zone of the landslide was identified. The areas of the topographic changes were mainly located on the main scarp, toe and secondary landslides. The topographic changes were influenced by rainfall and rill erosion. The geomorphologically-guided InSAR interpretation method was applied to explore the displacement pattern. The deformation area in the middle of the landslide coincided with the secondary landslides. A time-series InSAR analysis revealed the dynamic evolution of the deformation before and after the landslide. Based on its evolution, the simulated landslide process included the main landslide and three secondary landslides. Based on the displacement of the longitudinal ground surface profiles, the displacement characteristics and kinematic behavior were summarized and compared with those of a single rotational landslide and multiple rotational landslides. The single rotational landslide had obvious secondary and progressive characteristics, developing into multiple rotational landslides triggered by conditions such as rainfall. [ABSTRACT FROM AUTHOR]

In the winter of 1714–1715, a large rotational landslide originated on the northern slope of the Sierra de Aralar (Navarra, Spain), generating an earthflow that slowly descended through the valley for a kilometer and a half destroying the village of Inza. An interdisciplinary research recreated the historical process of the event and the geomorphological characterization of this large landslide. The geological analysis and hydrogeological characteristics of the site also identified the determining factors of this historical event. From the analysis that triggered the landslide and how the climate affected events can now be demonstrated from historical records of excess rainfall and the initial start of the process. From the recreated pre-failure topography, the stability of the original slope was studied using a 3D numerical model to identify the factors, causes and mechanism that controlled the development of the landslide. [ABSTRACT FROM AUTHOR]

The deformation characteristics and instability patterns of rotational landslides are complicated. Such landslides are large and occur continuously, seriously threatening people’s lives. We used interferometry synthetic aperture radar (InSAR), digital elevation models of difference (DODs), numerical simulations, and other techniques for analyzing the topographic changes, surface deformation and movement process before, during and after a landslide. Based on the high-resolution terrain data before and after the landslide, the topographic changes were analyzed, and the active zone of the landslide was identified. The areas of the topographic changes were mainly located on the main scarp, toe and secondary landslides. The topographic changes were influenced by rainfall and rill erosion. The geomorphologically-guided InSAR interpretation method was applied to explore the displacement pattern. The deformation area in the middle of the landslide coincided with the secondary landslides. A time-series InSAR analysis revealed the dynamic evolution of the deformation before and after the landslide. Based on its evolution, the simulated landslide process included the main landslide and three secondary landslides. Based on the displacement of the longitudinal ground surface profiles, the displacement characteristics and kinematic behavior were summarized and compared with those of a single rotational landslide and multiple rotational landslides. The single rotational landslide had obvious secondary and progressive characteristics, developing into multiple rotational landslides triggered by conditions such as rainfall.

A new segmentation method for detection of rotational landslides from two epochs of Light Detection and Ranging System data (LiDAR) was developed. The developed method is based on outlier detection using Z scores of standard normal distribution. In this method, outlying height differences were obtained from two epochs of LiDAR data. The height differences were determined for each ith point uniquely by gridding the area along the steepest slope direction. Then, each profile containing the outlying height differences was tested for conformity to a possible rotational landslide and grouped into horizontal sets. Finally, the procedure was applied to horizontally grouped sets in the direction perpendicular to the steepest slope to determine each rotational landslide. To test the developed method, the area containing five different sizes of rotational landslides was scanned by the developed method. The results showed that the developed method segmented the area successfully identifying each rotational landslide.

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The integration of data from different sources can be very helpful in understanding the mechanism, the geometry, the kinematic, and the area affected by complex instabilities, especially when the available geotechnical information is limited. In this work, the suitability of different techniques for the study of a deep-seated landslide affecting a bridge in Alcoy (Spain) is evaluated. This infrastructure presents such severe damage that has rendered the bridge unusable, which prevents normal access to an important industrial area. Differential SAR Interferometry (DInSAR) and terrestrial Light Detection and Ranging (LiDAR) remote sensing techniques have been combined with ground displacement monitoring techniques, such as inclinometers and conventional geological and geotechnical investigation, electrical-seismic tomography, damage, and topographic surveys, to determine the boundaries, mechanism, and kinematics of the landslide. The successful case study that is illustrated in this work highlights the potential and the need for integrating multi-source data for the optimal management of complex landslides and the effective design of remedial measurements.

El presente artículo describe las causas y dinámica del movimiento en masa del día 31 de mayo de 2008 en la parte alta del barrio San Pedro, sector Las Peñitas del municipio de Medellín, el cual dejó un saldo trágico de 27 personas muertas y 16 lesionadas, además de la destrucción de 20 viviendas del barrio El Socorro. Sumado a Rosellón (1927), Media Luna (1954), Santo Domingo (1974), Villatina (1987) y El Barro (2005), corresponde a uno de los eventos más trágicos que han golpeado el valle de Aburrá en toda su historia. Para la caracterización del área del evento se utilizaron estudios previos realizados por diferentes instituciones de reconocido prestigio; para la caracterización, descripción de la dinámica predominante del evento y sus causas se usaron evidencia de campo recolectada en recorridos sobre el terreno e inspección visual el mismo día en que ocurrió, de forma tal que no se modificara por las labores propias de rescate, y finalmente se recurrió a los datos de precipitación de diferentes estaciones hidrometeorológicas de Empresas Públicas de Medellín (EPM) y del Instituto de Hidrología, Meteorología y Estudios Ambientales de Colombia (IDEAM), con el fin de evaluar la influencia de la lluvia como elemento desencadenante. El evento inicial fue clasificado como un deslizamiento rotacional simple en dirección noreste, con una longitud aproximada de 60 m, el cual, debido a la saturación del material, se transformó en un movimiento tipo flujo de escombros que avanzó 140 m en dirección SE y NE. Como causas del evento se encuentran las pobres condiciones geomecánicas del material fuente y la cantidad de lluvia acumulada precedente de los últimos 15 días y antecedente del día 30 de mayo, cuando en tan solo 2 horas y 30 minutos cayeron 83,3 mm sobre la ciudad.The article presents the causes and dynamic of the mass movement which occurred on May 31, 2008 in the higher part of San Pedro settlement, called Las Peñitas, Medellín. This tragic event left 27 dead people, 16 injured people and 20 houses destroyed of El Socorro settlement. This event with Rosellón (1927), Media Luna (1954), Santo Domingo (1974), Villatina (1987) and El Barro (2005) represents one of the most tragic events in the Aburrá Valley history. For the characterization of the area of the event previous work from different recognized, prestigious institutions was used; for the characterization, description of the predominant dynamics of the event and its causes ground evidence collected on the terrain and visual inspection the same day when it occurred were used, so that it did not change due to proper rescue works. The data of rainfall hydrometeorological stations of Empresas Públicas de Medellín (EPM) and Colombian Institute of Hydrology, Meteorology and Environmental Studies (IDEAM) were used, with the purpose of evaluating the influence of rain like triggering element. The mass movement was classified as simple rotational landslide on NE direction, with a longitude around 60 m, which due to high saturation levels, it changed to an debris flow moving 140 m ahead on SE direction, and finally the mass turned NE. Triggering causes are associated to geomechanical properties of soil and antecedent rainfall of previous 15 days and very intense rainfall event during May 30, when 83.3 mm fell down for just 2 hours and 30 minutes along the central part of the valley.

The article presents the causes and dynamic of the mass movement which occurred on May 31, 2008 in the higher part of San Pedro settlement, called Las Peñitas, Medellín. This tragic event left 27 dead people, 16 injured people and 20 houses destroyed of El Socorro settlement. This event with Rosellón (1927), Media Luna (1954), Santo Domingo (1974), Villatina (1987) and El Barro (2005) represents one of the most tragic events in the Aburrá Valley history. For the characterization of the area of the event previous work from different recognized, prestigious institutions was used; for the characterization, description of the predominant dynamics of the event and its causes ground evidence collected on the terrain and visual inspection the same day when it occurred were used, so that it did not change due to proper rescue works. The data of rainfall hydrometeorological stations of Empresas Públicas de Medellín (EPM) and Colombian Institute of Hydrology, Meteorology and Environmental Studies (IDEAM) were used, with the purpose of evaluating the influence of rain like triggering element. The mass movement was classified as simple rotational landslide on NE direction, with a longitude around 60 m, which due to high saturation levels, it changed to an debris flow moving 140 m ahead on SE direction, and finally the mass turned NE. Triggering causes are associated to geomechanical properties of soil and antecedent rainfall of previous 15 days and very intense rainfall event during May 30, when 83.3 mm fell down for just 2 hours and 30 minutes along the central part of the valley. [ABSTRACT FROM AUTHOR]

An unstable rock slump, estimated at 5 to 10 × 106 m3, lies perched above the northern shore of Tidal Inlet in Glacier Bay National Park, Alaska. This landslide mass has the potential to rapidly move into Tidal Inlet and generate large, long-period-impulse tsunami waves. Field and photographic examination revealed that the landslide moved between 1892 and 1919 after the retreat of the Little Ice Age glaciers from Tidal Inlet in 1890. Global positioning system measurements over a 2-year period show that the perched mass is presently moving at 3–4 cm annually indicating the landslide remains unstable. Numerical simulations of landslide-generated waves suggest that in the western arm of Glacier Bay, wave amplitudes would be greatest near the mouth of Tidal Inlet and slightly decrease with water depth according to Green’s law. As a function of time, wave amplitude would be greatest within approximately 40 min of the landslide entering water, with significant wave activity continuing for potentially several hours. [ABSTRACT FROM AUTHOR]

Major postglacial rock slope failures are a common feature of the Scottish Highlands and other mountainous areas that were deglaciated at the end of the Pleistocene, but evaluation of the causes and triggers of failure has been hindered by a lack of reliable dating evidence. We report the result of a pilot study designed to establish the absolute age of a large postglacial rotational rockslide at The Storr on the Isle of Skye, Scotland, using 36 Cl surface exposure dating. Exposure ages of 6.3 ± 0.7 cal. ka BP and 6.6 ± 0.8 cal. ka BP were obtained for rock samples from two separate landslide blocks, giving an overall age estimate of 6.5 ± 0.5 cal. ka BP for rock slope failure at this site. This date is consistent with AMS radiocarbon dating of windblown sand derived from the failure scarp, and with previous inferences (based on relative dating evidence) concerning an early-Holocene age for most rock slope failures in the Scottish Highlands. The long time lag (. 7 ka) between deglaciation and failure suggests that progressive joint extension and shearing of rock bridges and asperities were of critical importance in conditioning failure, though a seismic trigger cannot be ruled out. The methodology of surface exposure dating in this context is described and its future potential assessed. [ABSTRACT FROM AUTHOR]

The integration of data from different sources can be very helpful in understanding the mechanism, the geometry, the kinematic, and the area affected by complex instabilities, especially when the available geotechnical information is limited. In this work, the suitability of different techniques for the study of a deep-seated landslide affecting a bridge in Alcoy (Spain) is evaluated. This infrastructure presents such severe damage that has rendered the bridge unusable, which prevents normal access to an important industrial area. Differential SAR Interferometry (DInSAR) and terrestrial Light Detection and Ranging (LiDAR) remote sensing techniques have been combined with ground displacement monitoring techniques, such as inclinometers and conventional geological and geotechnical investigation, electrical-seismic tomography, damage, and topographic surveys, to determine the boundaries, mechanism, and kinematics of the landslide. The successful case study that is illustrated in this work highlights the potential and the need for integrating multi-source data for the optimal management of complex landslides and the effective design of remedial measurements. [ABSTRACT FROM AUTHOR]