El libro Andar Andar, cómo disfrutar de un caballo peruano de paso, hace un enfoque general sobre el equino peruano, sus virtudes y los cada vez más reducidos espacios para practicar la equitación. Esta hermosa publicación cuenta con destacadas fotografías, y se encuentra dividido en tres partes (denominados andares). La primera es un acercamiento a sus virtudes, su crianza y la condición netamente peruana de la raza; la segunda gira en torno a la elección y el uso del equino; y en la tercera el autor plantea basándose en la tradición, la manera adecuada y responsable de disfrutarlo, así como los preparativos para una buena cabalgata.

En estos Alegatos sobre la educación en nuestro país, el ingeniero y docente José Dextre Chacón fundamenta, en siete brillantes capítulos, estrategias claras para la transformación social de nuestra cultura a través de la enseñanza. Desde su amplia experiencia y trayectoria en gestión educativa, el autor, fundador de la Universidad Científica del Sur, nos comparte en este libro acciones concretas con un profundo sentido humanista. Así, en estos ensayos se presentan los valores fundamentales sostenibles tanto en la enseñanza pública como en la privada, alentando la innovación y confiando en la inversión. Estamos ante un conjunto de lúcidas reflexiones de uno de los educadores y estrategas que más ha aportado a la transformación educativa en el Perú.

The Costa Tropical in Granada Province, in Southern Spain, was intensively developed during the 1980s and 90s. A complex of several residential communities was built on the eastern slope of the coastal Cerro Gordo hill (Almuñécar), on the pre-existing Calaiza landslide. This was not identified in the preliminary technical studies, thus giving rise to a set of incidents associated with this unforeseen unstable slope. To ensure sea views from all the houses, excavations and fillings were carried out, creating a stepped slope, on which the new foundations of structures and roads were located and subsequently damaged by an increasing number of cracks and deformations, leading to 42 houses becoming ruins in the period 2003–2016. Since 1990, annual and monthly rainfall has been variable in the area, and some rainfall peaks were eventually associated with damage proliferation, although more frequently damage was recorded during dry or low rainfall seasons, when water infiltrated from breaks in pipelines. This damage results from a combination of sliding and bad construction practices at increasing rates from dry to humid periods or during heavy rains. An overall perspective of the geotechnical and geomorphological features of the study area, the landslide reactivation, and its correlation with the damage evolution, as well as its legal consequences, is presented here.

This paper presents a review of the data acquisition procedures of geotechnical parameters for rock slope stability assessment and the proposal of some new improvements. For this purpose, a piece of research based on the slope mass rating classification system using close-range terrestrial digital photogrammetry (CR-TDP) has led to improvements in quality and timing of discontinuity data acquisition, and analyzes the suitability of each one of the parameters when applied to weak foliated rocks. TDP allows rapid 3D image acquisition of a rock slope, which can be analyzed using software to determine the geometrical parameters that affect stability. A fast procedure to perform the photogrammetric, non-contact survey in order to obtain the 3D images is shown in this paper. Being a rapid and single-person task, this procedure provides enough precision to be applied to weak foliated rock slopes with non-well-defined geometry. Furthermore, the study has focused on highly foliated rock outcrops, in which high resolution in the 3D images is very desirable. This research was applied to mountain road cuts, in which the use of TDP with a very close range was necessary. Through an application on weak rocks in the Alpujarras (Andalusia, Spain), this work analyzes the bias when applying TDP to materials such as these, under progressive weathering processes.

Landslide hazard in a region limited to data from a regional scale about triggering factors is assessed via cross tabulation between determining factors and landslides with recent activity. Firstly, landslide susceptibility was evaluated and validated through a bivariate statistical method between the previously identified stability conditioning factors and the mapped landslides. In this way, the most susceptible areas for assessing landslide hazards were selected. The main problem to solve in this type of research is the landslide activity. For this purpose, several techniques were applied: news reports, differential interferometric synthetic aperture radar, digital photogrammetry, light detection and ranging, photointerpretation, and dendrochronology. Both the strong and weak points of these techniques are also mentioned. The landslide return period was computed via the association between landslide activity and triggering factors, in this case annual rainfall. Finally, landslide hazard was mapped solely based on landslides with recent activity and their computed return period. The relationship between landslide occurrence and triggering factors shows that, according to both the considered assumptions and the observations made, deep-seated landslides are triggered or reactivated together with superficial landslides once every 18 years, while superficial landslides as flows or falls occur once every 5 years. The results show that there is generally a low landslide hazard in the study zone, especially when compared to landslide susceptibility. This means that landslides are mainly dormant from a natural evolution point of view, but could be reactivated as a result of geomorphological, climate, or human changes. In any case, the landslide hazard is successfully assessed, with a prediction of a 6% annual probability of a high hazard in 5% of the area, intersecting with the main infrastructures of the region; thus, control strategies are justified in order to avoid damage in extraordinary rainfall periods.

In this work a detailed analysis of the temporal evolution of the Almegíjar landslide is presented. It is a rock slide located in the Alpujarras region (Granada, Spain) that has developed over the last 30 years. Six datasets and photogrammetric flights corresponding to the years 1956, 1984, 1992, 2001, 2008, and 2010 were surveyed. The more recent flight of 2010 combined an aerial digital camera and a LiDAR sensor and was oriented by means of in-flight data and tie points. This 2010 flight allowed for the generation of a reliable and high-precision Digital Terrain Model (DTM). The other flights were oriented using second-order ground control points transferred from the 2010 flight, and the corresponding DTMs were prepared by automatic matching and subsequent editing from the stereoscopic models. After comparing the DTMs of different dates, it has been observed that the landslide was triggered after 1984 and since then has evolved in an irregular pattern with periods of variable activity. On average, the ground surface dropped more than 8 m in depleted zones and rose nearly 4 m in the accumulation zones, with a velocity catalogued as very slow (about 15–30 cm/year) over a time span corresponding to a degree VIII of diachroneity. The total volume of the mobilized mass of this large contemporary slide was about 300 × 103 m3.

The denudation of young reliefs prone to landslides can have severe consequences for society and the environment. However, landslide databases and the additional information (landslide type, date and triggering factors) necessary to deal with landslide hazard assessment and the development of effective and reliable landslide warning systems are usually scarce or non-existent. In this way, by taking into account the date of landslide events and by expanding the analysis of cumulative rainfall from these dates to a broader time period that includes the days or months leading up to a landslide, the corresponding triggering rainfall threshold can be assessed more accurately. In this paper, a methodology based on a partial duration series analysis applied to rainfall variables allows the possibility to better understand precipitation patterns. Another advantage of analysing precipitation variables within a broader time period is the ability to identify greater accuracy rainfall anomalies such as extreme rainfalls with their return period related to a low number of dated landslide events (in this case, 20 landslide events). The landslide spatial distribution within a regional area requires the processing and analysis of data from multiple long-term historical daily rainfall records from different rainfall gauges, which notably increase the number of calculations to be dealt with. To overcome this inconvenience, these processes were streamlined by using macro-automation. Additionally, different rainfall durations can be interactively identified from graphical outputs that show anomalies on more than one rainfall variable after applying this methodology. Among these rainfall variables, the antecedent accumulated rainfall (A1) was found to be the most suitable to apply the occurrence probability analysis. When compared to other variables, the return period values of A1 were determined to be conservative, neither too high nor too low. Using this approach, the return period curve was shown to be an important graphic object in detecting uncommon rainfalls that are contemporaneous or previous to landslides. The relevant findings of this research show a power-law trend with α = 88.005 and β = 0.69 in the correlation of intensity and duration associated with antecedent cumulative rainfall (A1) anomalies. The mean return period for these anomalies resulted in 12.4 years, while for 50 % of the landslides, the recurrence interval was estimated in less than or equal to 3.6 years. In addition, significant differences were found between catalogued slope-cut failures and natural landslides. Moreover, differences were also found between simplified types of natural landslides.

In the procedures to minimize diachronic landslides, data on their temporal evolution and destructive capacities are necessary. For that purpose, remote-detection techniques proved to be highly useful for quantifying the ongoing change in the relief, as well as in comparisons between digital terrain models achieved by Light Detection and Ranging. The methodology presented in this paper includes the supervised merging and comparison of sequential scans, acquired within nearly annual intervals from an irregular terrain, which improves the quality of the results highlighting ground changes. This approach is based on the processing of digital terrain models from point clouds acquired by Terrestrial Laser Scanning to quantify and interpret the landslide displacements. In parallel, it is supported by Global Navigation Satellite Systems, the use of artificial targets and a refined data processing to minimize the uncertainty and improve the precision of the results. This is applied to a large translational slide affecting phyllite rocks in a IV-V degree of weathering settled on the southern slope of Sierra Nevada (south-eastern Spain). During the monitoring period (2008–2010), the slide remained inactive until 2009, followed by a reactivation with displacements in the range −1.80 to 1.20 m along the period 2009–2010, where negative values are downwards from the reference model (2009). The accumulated relative standard deviation between data sets was on the order of 7.5 cm, whereas the threshold to determine a terrain displacement (also avoiding changes due to erosion-accumulation processes) was of 10 cm. When applying this methodology to Airborne Laser Scanning datasets for the years 2008 and 2010, covering zones hidden to the line of sight of the terrestrial technique, a reactivation with similar deformation pattern was found useful to validate the findings, although the detail of changes and quantitative results did not match exactly due to the different accuracy and resolution of both techniques. The reactivation of the slide coincided with a period of intense rains, pointing to this as the triggering factor, with a precipitation threshold of roughly 1000 mm in a period of 4 months, only reached on one occasion throughout in the historical record.

Previous research has shown a visual asymmetry in shaded stimuli where the perceived contrast depended on the polarity of their dark and light areas (Chacón, 2004). In particular, circles filled out with a top-dark luminance ramp were perceived with higher contrast than top-light ones although both types of stimuli had the same physical contrast. Here, using shaded stimuli, we conducted four experiments in order to find out if the perceived contrast depends on: (a) the contrast level, (b) the type of shading (continuous vs. discrete) and its degree of perceived three-dimensionality, (c) the orientation of the shading, and (d) the sign of the perceived contrast alterations. In all experiments the observers' tasks were to equate the perceived contrast of two sets of elements (usually shaded with opposite luminance polarity), in order to determine the subjective equality point. Results showed that (a) there is a strong difference in perceived contrast between circles filled out with luminance ramp top-dark and top-light that is similar for different contrast levels; (b) we also found asymmetries in contrast perception with different shaded stimuli, and this asymmetry was not related with the perceived three-dimensionality but with the type of shading, being greater for continuous-shading stimuli;

In this work, a simple methodology is presented for processing high-resolution topographical data over wide areas. It is based on digital elevation model of differences (DEMoD) among high-resolution digital models (HRDEM) produced from light-detection and ranging (LiDAR) data. Because these qualitative approaches based on HRDEMs can be affected by errors related to misalignment between different passes of the airborne sensor and errors in classifying points, a simplified strategy was undertaken for their semi-automatic correction and supervision for analyzing geomorphological changes. Besides, it became possible to detect, delineate, and classify a total of 47 natural landslides and 50 slope-cut failures over an area of 234 km2 on the basis of the analysis of the LiDAR products (DEMs and DEMoD) and the orthophotography imagery inspection integrated in a geographical information system (GIS). Most of the displacements detected were probably generated during the winter of 2009–2010 when a new record of cumulative rainfall was reached. The displacement rate of these movements cannot be known with precision, but the minimum velocity that can be obtained is 0.3 m/year regarding the period between the two data acquisitions carried out in November 2008 and July 2010. On the other hand, a comparison was made of the existing susceptibility maps with respect to this new inventory, which indicated greater landslide frequency in areas of moderate susceptibility levels. The influence of treating inventories at different temporal scales is discussed.

Previous research has shown a visual asymmetry in shaded stimuli where the perceived contrast depended on the polarity of their dark and light areas (Chacón, 2004). In particular, circles filled out with a top-dark luminance ramp were perceived with higher contrast than top-light ones although both types of stimuli had the same physical contrast. Here, using shaded stimuli, we conducted four experiments in order to find out if the perceived contrast depends on: (a) the contrast level, (b) the type of shading (continuous vs. discrete) and its degree of perceived three-dimensionality, (c) the orientation of the shading, and (d) the sign of the perceived contrast alterations. In all experiments the observers’ tasks were to equate the perceived contrast of two sets of elements (usually shaded with opposite luminance polarity), in order to determine the subjective equality point. Results showed that (a) there is a strong difference in perceived contrast between circles filled out with luminance ramp top-dark and top-light that is similar for different contrast levels; (b) we also found asymmetries in contrast perception with different shaded stimuli, and this asymmetry was not related with the perceived three-dimensionality but with the type of shading, being greater for continuous-shading stimuli; (c) differences in perceived contrast varied with stimulus orientation, showing the maximum difference on vertical axis with a left bias consistent with the bias found in previous studies that used visual-search tasks; and (d) asymmetries are consistent with an attenuation in perceived contrast that is selective for top-light vertically-shaded stimul

This introduction provides some clues, aims and scope intended for the presentation of papers and also to define the objectives expected for session C6. Authors dealing with Urban Landslides are invited to contribute with their papers and also participating in the final session.

The Southern flank of Sierra Nevada and coastal Mediterranean areas of South Spain, in the Andalusian Granada Province, a high number of urban settlements and roads have been affected by landslides and instability problems since the fifties. In this period, a very quick economic development with an intense annual increase of touristic demand gave place to rapid enlargements of formerly small villages, and the widespread land-use change from agricultural to urban not only around the pre-existing urban centres, but also in many new developed lands along the coast for urbanization or leisure services. This Mediterranean coast, in the uplifting section of the Eurasia an African plates, is mainly excavated on metapelites of the Betic Cordillera Internal Zone, showing very inclined if not vertical slopes on Lower Triassic to Paleozoic series of marble, schist, phyliite and quartzite units, very deformed and weathered, so giving place to instability problems which are described in this paper.

The results of a geotechnical research on Holocene alluvial deposits in 14 municipalities of the Granada basin are presented, and a procedure to draw a geotechnical map of foundation conditions, using ArcGIS 9.3 (ESRI 2009) is described. Three different alluvial soil units were distinguished: (1) cohesive soils; (2) cohesive and fine granular soil; (3) coarse granular soil, based on their properties concerning grain size, bulk density, cohesion, internal friction angle, and N-SPT value. The actual building structures have predominantly shallow foundations. The definition of the minimum depth to actual foundation level was based on the analysis of thickness of disturbed soils, man-made fillings, depth to the water table and bearing capacity. The depth to actual foundation levels varies from 0.5 to 4 m in the study area. Concerning the ground, the geotechnical data compiled on foundation conditions show a high heterogeneity expressed by the spatial distribution of the basic properties in the three distinguished units of cohesive, cohesive and fine-granular, and coarse granular soils, respectively. The fine-grained alluvial soil units (cohesive) have a low bearing capacity varying between 40 and 100 kPa and are associated with a shallow water table appearing near the surface. In contrast, across the wide extension of the coarse-grained alluvial soil unit, a bearing capacity ranging from 60 to 300 kPa is determined; this unit is associated with a deep water table appearing at more than 40 m below the surface. The usefulness of the obtained geotechnical map of foundation conditions extends to the analysis of further alternatives of urban expansion and for the delimitation of future trends for of land-use-development processes in the metropolitan area of Granada, mainly at local and regional scales.

Forward logistic regression has allowed us to derive an earth-flow susceptibility model for the Tumarrano river basin, which was defined by modeling the statistical relationships between an archive of 760 events and a set of 20 predictors. For each landslide in the inventory, a landslide identification point (LIP) was automatically produced as corresponding to the highest point along the boundary of the landslide polygons, and unstable conditions were assigned to cells at a distance up to 8 m. An equal number of stable cells (out of landslides) was then randomly extracted and appended to the LIPs to prepare the dataset for logistic regression. A model building strategy was applied to enlarge the area included in training the model and to verify the sensitivity of the regressed models with respect to the locations of the selected stable cells. A suite of 16 models was prepared by randomly extracting different unoverlapping stable cell subsets that have been appended to the unstable ones. Models were finally submitted to forward logistic regression and validated. The results showed satisfying and stable error rates (0.236 on average, with a standard deviation of 0.007) and areas under the receiver operating characteristic (ROC) curve (AUCs) (0.839 for training and 0.817 for test datasets) as well as factor selections (ranks and coefficients). As regards the predictors, steepness and large-profile and local-plan topographic curvatures were systematically selected. Clayey outcropping lithology, midslope drainage, local and midslope ridges, and canyon landforms were also very frequently (from eight to 15 times) included in the models by the forward selection procedures. The model-building strategy allowed us to produce a performing earth-flow susceptibility model, whose model fitting, prediction skill, and robustness were estimated on the basis of validation procedures, demonstrating the independence of the regressed model on the specific selection of the stable cells.

This paper presents a new, fast and economical method for digitizing a rock surface profile to determine its joint roughness coefficient (JRC) value (Barton and Choubey, Rock Mech Rock Eng 10:1–54, 1977) using a set of existing parameters, the appropriateness of which has been tested. The new procedure was applied to four rock road cuts in the Alpujarra area of Granada province (Andalusia, Spain), supported by 117 digitized profiles. The method avoids any personal subjectivity bias. The usual subjectivity in the visualization and assessment of the JRC value is estimated here by a survey test answered by 90 trained users. The survey test consisted of a set of JRC visual comparisons of 12 roughness profiles, selected from the 117 profiles surveyed during the field research in the Alpujarra region, with the Barton typical profiles. The results of the survey clearly show systematic inaccuracies in the traditional procedure that are reduced if the advice presented in the conclusions of this paper is taken in account when performing the visual estimation.

A procedure to select the controlling factors connected to the slope instability has been defined. It allowed to assess the landslide susceptibility in the Rio Beiro basin (about 10 km2) over the north-eastern area of the city of Granada (Spain). Field and remote (Google EarthTM) recognition techniques allowed to generate a landslide inventory consisting in 127 phenomena. Univariate tests, using both association coefficients and validation results of single parameter susceptibility models, allowed to select among 15 controlling factors the ones that resulted as good predictor variables; these have been combined for unique conditions analysis and susceptibility maps were finally prepared. In order to verify both the goodness of fit and the prediction skill of the susceptibility models, two different validation procedures were applied and compared. Both procedures are based on a random partition splitting of the landslide archive for producing a test and a training subset. The relative error, considered between the intersected target landslides by the different susceptibility classes, was used to estimate the predictive skill of the maps.

In this work a methodology for preparing landslides susceptibility and hazard maps is presented, based in a bivariate analysis between past movements and determinant factors. The methodology for determining the susceptibility is an adaptation of the matrix method to a GIS, and it has been tested and validated in different zones and environments of Andalusia (southern Spain). The text also discusses the availability of information layers in Spanish SDI to developing these susceptibility maps. For the hazard evaluation, we propose a methodology of determining the susceptibility in different return periods from inventories of landslides that show activity in these considered periods. The activity was estimated from stereoscopic and monoscopic analysis of aerial photographs from different dates, using geological and geomorphic criteria, and the study of rainfall time series. Since all, four periods were considered in a logarithmic scale of 10 years (approximate return period of rainfall generating instability in the area), 100, 1000 and 10000 years. After determining the susceptibility, it was transformed into annual hazard dividing by the number of years of the return period. Finally, a total hazard map was obtained by determining at each point the maximum value of hazard of the different periods and it is expressed in several intervals.