Mass movement can be activated by earthquakes, rapid snowmelt, or intense rainstorms in conjunction with gravity. Whereas mass movement plays a major role in the evolution of a hillslope by modifying slope morphology and transporting material from the slope to the valley, it is also a potential natural hazard. Determining the morphology of the mountain slopes and the relationships of frequency and magnitude of landslides are fundamental to understanding the role of landslides in the study of landscape evolution, and hazard assessment. Characteristics of the geomorphic zones in a periglacial landscape were evaluated by plotting local slopes and the drainage areas in Paonia-McClure Pass area of western Colorado. The study suggested that the steepness and concavity of mountain slopes and stream channels in the study area are related by an exponential equation. Seven hundred and thirty five shallow landslides (<160,000 m2) from the same study area were mapped to determine the frequency-magnitude relationships of shallow landslides and to develop an optimum model of mapping susceptibility to landslides. This study suggests that the frequency-magnitude of the landslides in Paonia-McClure Pass area are related by a double pareto equation with values α= 1.1, and β = 1.9 for the exponents. The total area of landslides is 4.8x10⁶ m² and the total volume of the landslides is 1.4x10⁷ m³. The areas (A) and the volumes (V) of landslides are related by V = 0.0254xA^1.45. The frequency-magnitude analysis shows that landslides with areas ranging in size from 1,600 m2 - 20,000 m2 are the most hazardous landslides in the study area. These landslides are the most frequent and also do a significant amount of geomorphic work. Three quantitative approaches: weight of evidence; fuzzy logic; and logistic regression; were employed to develop models of mapping landslides in western Colorado. The weight of evidence approach predicted 78 percent of the observed landslides, the fuzzy-logic approach also predicted 78 percent of the observed landslides, and the logistic regression approach predicted 86 percent of the observed landslides.

The purpose of this study is to evaluate and to compare the results of bivariate statistical analysis conducted with three different data sets in Geographical Information Systems (GIS) based landslide susceptibility mapping applied to the Devrek region. The data sets are created from the seed cells of crowns and flanks, only crowns, and only flanks of the landslides by using 10 different parameters of the study area. To increase the data dependency of the analysis, all parameter maps are classified into equal frequency classes based directly on the percentile divisions of each seed cells data set. The resultant maps of the landslide susceptibility analysis indicate that all data sets produce acceptable results. In each seed cell data set analysis, elevation, lithology, slope, aspect and drainage density parameters are found to be the most contributing factors in landslide occurrences. The results of the three data sets are compared by Seed Cell Area Index (SCAI). This comparison shows that the crowns data set produces the most accurate and successful landslide susceptibility map of the study area.

Koyulhisar settlement area is located on the northern flank of Kelkit valley which is seismically active and landslide-prone area. The settlement area was adversely affected from active landslides and some of the houses were evacuated. The purpose of this thesis is to delineate areas where slope instability exists within the Koyulhisar settlement area, and to investigate an active landslide by means of field observations, drilling, sampling, field and laboratory testing, and in-situ monitoring using inclinometer. Based on the field studies, it is observed that flyschoidal sequence as bedrock and colluvium consisting clay and silt with some gravel are the main lithological units exposed in the study area. Two landslide affected areas are identified, the one investigated due to its adverse effect to some important governmental buildings, has a non-circular failure surface due to the existence of the flyschoidal sequence below the colluvium. The inclinometer measurements reveal that the displacements are local and their velocities are generally less than 14 mm/year indicating that the landslide is an extremely slow landslide. In addition, high groundwater table is observed as one of the major parameters in occurrence of landslide.

The rigid sliding-block analysis introduced by Newmark in 1965 has become a popular method for assessing the stability of slopes during earthquakes. Estimates of sliding displacement calculated using this methodology serve as an index of seismic performance and are used for mapping seismic landslide hazard potential. The original approach of rigorously integrating ground acceleration time-histories to compute estimates of sliding displacement has been replaced by the use of simple, empirical models that predict displacement as a function of a slope's yield acceleration and one or more measures of ground shaking. To be useful the results of these models must be compared with observations of landslides from previous earthquakes. Seven different empirical models were evaluated by comparing predicted displacements with an inventory of observed landslides from the 1994 Northridge, California earthquake. Using a comprehensive set of ground motion data and shear strength properties from the Northridge earthquake, sliding displacements were calculated within a geographic information system (GIS) and the accuracy of each model was computed. The influence of factors such as landslide size, geologic unit, slope angle, and material strength on the prediction of landslides was also evaluated. The results were used to show that the accuracy of the predictive models depends less on the model used and more on the uncertainty in the model parameters, specifically the assigned shear strength values. Because current approaches do not take into account the spatial variability of strength within individual geologic units, the accuracy of the predictive models is controlled by the distribution of slope angles within observed and predicted landslide cells. Assigning overly conservative (low) shear strength values results in a higher percentage of landslides accurately identified, but also results in a large over-estimation of the seismic landslide hazard. / text

Στα πλαίσια της παρούσας διατριβής έγινε θαλάσσια έρευνα στην περιοχή των Νικολέϊκων Αιγίου, στην οποία έχουν εκδηλωθεί φαινόµενα βαρυτικής µετακίνησης µαζών τόσο σε ιστορικούς χρόνους όσο και στο πρόσφατο παρελθόν. Με σκοπό τη µελέτη των φαινοµένων αυτών εκτελέστηκαν στην περιοχή ερευνητικές πορείες σε διαφορετικές χρονικές περιόδους. Κατά τις πορείες αυτές έγινε γεωφυσική διασκόπιση του πυθµένα και οπτική παρατήρηση των υποθαλάσσιων ιζηµάτων. Κύριος στόχος της έρευνας ήταν η όσο το δυνατό καλύτερη µορφολογική αποτύπωση του πυθµένα, η αναγνώριση και χαρτογράφηση των διαφόρων κατολισθητικών ενοτήτων και η διερεύνηση φαινοµένων που πιθανόν σχετίζονται γενετικά µε την κατολίσθηση (διαφυγές αερίων υδρογονανθράκων). Αποτέλεσμα της μελέτης αυτής ήταν η οριοθέτηση της υποθαλάσσιας κατολίσθησης στην παράκτια ζώνη των Νικολέϊκων, ο προσδιορισμός των κυριότερων μορφολογικών χαρακτηριστικών της, η συμπεριφορά των ιζημάτων από τη χρονική στιγμή μετακίνηση τους έως σήμερα και η προσέγγιση των γενετικών μηχανισμών της κατολίσθησης. / On june 15th, 1995, an earthquake of magnitude Ms 6,1R occured offshore of the Aigion town in the Western Gulf of Corinth. An offshore survey using a 3.5 kHz subbotom profiling system, which carried out fifteen days after the main shock has shown that the earthquake caused a small-size subaerial to submarine landslide in the Eliki fan delta deposits. Further examination of the landslide, using a side scan sonar system and R.O.V for the visual inspection of the seafloor to map the complex seafloor morphology in and adjacent to the landslide, has shown that the Eliki submarine landslide is a complex low-angle translatory slide less than 5 m deep and that the sliding took place over a single basal glide plane dipping at about 1o. The instability mechanism that triggered the landslide is liquefaction of a subsurface horizon at a depth of 5 m as suggested by the presence of sand and water injection features (sand boils) in the beach near the slide site and the conical depressions observed on the seafloor. Gas expulsions from the liquefied horizon perhaps enhanced the failure as suggested by the presence of gas charged sediments under the sliding plane and the rising of bubbles in the water column as observed by the fishermen.

No description available.

Landslides are one of the biggest natural hazards in Georgia, a mountainous country in the Caucasus. So far, no systematic monitoring and analysis of the dynamics of landslides in Georgia has been made. Especially as landslides are triggered by extrinsic processes, the analysis of landslides together with precipitation and earthquakes is challenging. In this thesis I describe the advantages and limits of remote sensing to detect and better understand the nature of landslide in Georgia. The thesis is written in a cumulative form, composing a general introduction, three manuscripts and a summary and outlook chapter. In the present work, I measure the surface displacement due to active landslides with different interferometric synthetic aperture radar (InSAR) methods. The slow landslides (several cm per year) are well detectable with two-pass interferometry. In same time, the extremely slow landslides (several mm per year) could be detected only with time series InSAR techniques. I exemplify the success of InSAR techniques by showing hitherto unknown landslides, located in the central part of Georgia. Both, the landslide extent and displacement rate is quantified. Further, to determine a possible depth and position of potential sliding planes, inverse models were developed. Inverse modeling searches for parameters of source which can create observed displacement distribution. I also empirically estimate the volume of the investigated landslide using displacement distributions as derived from InSAR combined with morphology from an aerial photography. I adapted a volume formula for our case, and also combined available seismicity and precipitation data to analyze potential triggering factors. A governing question was: What causes landslide acceleration as observed in the InSAR data? The investigated area (central Georgia) is seismically highly active. As an additional product of the InSAR data analysis, a deformation area associated with the 7th September Mw=6.0 earthquake was found. Evidences of surface ruptures directly associated with the earthquake could not be found in the field, however, during and after the earthquake new landslides were observed. The thesis highlights that deformation from InSAR may help to map area prone landslides triggering by earthquake, potentially providing a technique that is of relevance for country wide landslide monitoring, especially as new satellite sensors will emerge in the coming years. / Erdrutsche zählen zu den größten Naturgefahren in Georgien, ein gebirgiges Land im Kaukasus. Eine systematische Überwachung und Analyse der Dynamik von Erdrutschen in Georgien ist bisher nicht vorhanden. Da Erdrutsche durch extrinsische Prozesse ausgelöst werden, wird ihre Analyse zusammen mit Niederschlag und Erdbeben zu einer besonderen Herausforderung. In dieser Dissertation beschreibe ich die Potenziale und Limitierungen der Fernerkundung für die Detektion und das Verständnis von Erdrutschen in Georgien. Die Arbeit ist in einer kumulativen Form geschrieben, und besteht aus einer allgemeinen Einführung, drei Manuskripten sowie einer Zusammenfassung und einem Ausblick. In der vorliegenden Arbeit, Gestimme ich die Oberflächenverschiebung von aktiven Erdrutschen mit Methoden der Radarinterferometrie (InSAR). Die langsamen Erdrutsche (cm pro Jahr) konnten im einfachen Vergleich zeitlich unterschiedlicher Radaraufnahmen (two-pass InSAR), gut nachgewiesen werden. Die extrem langsamen Erdrutsche (mm pro Jahr) konnten hingegen nur mit InSAR Zeitreihentechniken nachgewiesen werden. Der Erfolg der angewandten InSAR Techniken wird durch die erfolgreiche Identifikation von bisher unbekannten Erdrutschen in Zentral Georgien veranschaulicht. Sowohl das Ausmaß als auch die Verschiebungsrate der Erdrutsche wurden quantifiziert. Ferner, um die mögliche Tiefe und Lage von potentiellen Gleitflächen zu bestimmen, wurden inverse Modelle entwickelt. Inverse Modellierung sucht nach Parametern der Quelle, welche die beobachtete Verschiebungsverteilung reproduzieren können. Ferner habe ich anhand der ermittelten Verschiebungsverteilung aus InSAR in Verbindung mit der Morphologie aus Luftaufnahmen das Volumen der untersuchten Erdrutsche empirisch abgeleitet. Ich habe eine Volumenformel für unseren Fall angepasst, und die verfügbaren Datensätze bezüglich Seismizität und Niederschlag kombiniert, um potenzielle auslösende Faktoren zu analysieren. Eine leitende Frage hierbei war: Was sind die Ursachen für die Beschleunigung von Erdrutschen, wie sie in den InSAR Daten beobachtet werden konnte? Das Untersuchungsgebiet in Zentral Georgien ist seismisch sehr aktiv. Als zusätzlichen Produkt der InSAR Datenanalyse wurde ein Deformationsgebiet gefunden, welches im Zusammenhang mit dem Mw=6.0 Erdbeben vom 7. September 2009 zusammenhängt. Beweise für Oberflächenbrüche, die direkt mit dem Erdbeben zusammenhängen, konnten in dem Gebiet nicht gefunden werden, jedoch konnten während und nach dem Erdbeben neue Erdrutsche beobachtet werden. Die Dissertation unterstreicht, dass Verformungsinformationen aus InSAR Analysen helfen können ein Gebiet, welches von Erdbebeninduzierten Erdrutschen gefährdet ist, zu kartieren. Potenziell stellt InSAR eine Technik dar, die von Bedeutung für die landesweite Überwachung von Erdrutschen sein kann, insbesondere im Hinblick auf die neuen Satellitensensoren, die in den kommenden Jahren verfügbar sein werden.

Landslides have occurred throughout the Holocene geologic epoch and they continue to occur in the Peace River Lowlands of Alberta and British Columbia. This study was conducted to provide an understanding of the processes and extents of one such landslide situated on a major slope at the Town of Peace River, Alberta by means of geophysical techniques with the aim of reducing the geohazard risk to lives and infrastructures. The geophysical characterization involved the acquisition, processing, and joint interpretation of seismic reflection, seismic refraction tomography, vertical seismic profile, and electrical resistivity tomography datasets, thereby providing important information about the subsurface geometry of the landslide, insights into the material properties of the unstable mass in contrast to that of the stable rock, and possible causes of the landslide. This contribution shows that putting considerable efforts into the acquisition and processing of geophysical datasets can yield valuable functional details. / Geophysics

Thesis (Ph. D.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on June 29, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Geotechnical Engineering, Civil and Environmental Engineering Department, University of Alberta." Includes bibliographical references.

Thesis (M.S. in civil engineering)--Texas A&M University, May 2007. / Includes bibliographical references (leaves 46-47). Also available online.