15 research outputs found
Optimization of health facility locations in Osh City, Kyrgyzstan
Basic information regarding location of existing facilities, their accessibility and development trends, in relation to socio-economic structure of a city is needed in order to prepare its developmental plan. Re-location of any service may not be feasible economically, but location-allocation models can be used to identify new potential locations. This study is an attempt to simulate new potential locations and evaluate the feasibility of optimization models for planning additional health facility in the Osh city. The result of the study shows the potential of the p-median approach for optimization of the location of various public services. The contribution of GIS to optimization techniques is mainly its use as a method for data gathering and visualization of the result. These two technologies can be fully integrated to provide a powerful tool for spatial decision support
SAR Interferometrie Analyse von ErdoberflÀchen-VerÀnderungen im tektonisch aktiven Pamir-Tien Shan Gebirge - Schwerpunkt auf koseismische Verformung und Hangrutschungen
This thesis presents new approaches of SAR methods and their application to tectonically active systems and related surface deformation. With 3 publications two case studies are presented:
(1) The coseismic deformation related to the Nura earthquake (5th October 2008, magnitude Mw 6.6) at the eastern termination of the intramontane Alai valley. Located between the southern Tien Shan and the northern Pamir the coseismic surface displacements are analysed using SAR (Synthetic Aperture RADAR) data. The results show clear gradients in the vertical and horizontal directions along a complex pattern of surface ruptures and active faults. To integrate and to interpret these observations in the context of the regional active tectonics a SAR data analysis is complemented with seismological data and geological field observations. The main moment release of the Nura earthquake appears to be on the Pamir Frontal thrust, while the main surface displacements and surface rupture occurred in the footwall and along of the NEâSW striking Irkeshtam fault. With InSAR data from ascending and descending satellite tracks along with pixel offset measurements the Nura earthquake source is modelled as a segmented rupture. One fault segment corresponds to high-angle brittle faulting at the Pamir Frontal thrust and two more fault segments show moderate-angle and low-friction thrusting at the Irkeshtam fault. The integrated analysis of the coseismic deformation argues for a rupture segmentation and strain partitioning associated to the earthquake. It possibly activated an orogenic wedge in the easternmost segment of the Pamir-Alai collision zone. Further, the style of the segmentation may be associated with the presence of Paleogene evaporites.
(2) The second focus is put on slope instabilities and consequent landslides in the area of prominent topographic transition between the Fergana basin and high-relief Alai range. The Alai range constitutes an active orogenic wedge of the Pamir â Tien Shan collision zone that described as a progressively northward propagating fold-and-thrust belt. The interferometric analysis of ALOS/PALSAR radar data integrates a period of 4 years (2007-2010) based on the Small Baseline Subset (SBAS) time-series technique to assess surface deformation with millimeter surface change accuracy. 118 interferograms are analyzed to observe spatially-continuous movements with downslope velocities up to 71 mm/yr. The obtained rates indicate slow movement of the deep-seated landslides during the observation time. We correlated these movements with precipitation and seismic records. The results suggest that the deformation peaks correlate with rainfall in the 3 preceding months and with one earthquake event. In the next step, to understand the spatial pattern of landslide processes, the tectonic morphologic and lithologic settings are combined with the patterns of surface deformation. We demonstrate that the lithological and tectonic structural patterns are the main controlling factors for landslide occurrence and surface deformation magnitudes. Furthermore active contractional deformation in the front of the orogenic wedge is the main mechanism to sustain relief. Some of the slower but continuously moving slope instabilities are directly related to tectonically active faults and unconsolidated young Quaternary syn-orogenic sedimentary sequences. The InSAR observed slow moving landslides represent active deep-seated gravitational slope deformation phenomena which is first time observed in the Tien Shan mountains. Our approach offers a new combination of InSAR techniques and tectonic aspects to localize and understand enhanced slope instabilities in tectonically active mountain fronts in the Kyrgyz Tien Shan.Die vorliegende Arbeit stellt neue AnsĂ€tze zu Methoden des âSynthetic Aperture Radarâ (SAR) vor und wendet diese auf tektonisch aktive Systeme und die damit einhergehende OberflĂ€chenverformung an. In drei wissenschaftlich begutachteten Publikationen in internationalen Fachzeitschriften werden im wesentlichen zwei Fallstudien prĂ€sentiert:
(1) Die koseismische Verformung in Folge des Nura-Erdbebens (5. Oktober 2008, Mw 6.6) am östlichen Rand des intramontanen Alai-Beckens. Die koseismischen Verformungen an der ErdoberflĂ€che wurden im Bereich zwischen dem sĂŒdlichen Tien Shan und dem nördlichen Pamir mit Hilfe von SAR (âSynthetic Aperture Radarâ) Daten analysiert. Die Ergebnisse zeigen klare, sowohl horizontale als auch vertikale Gradienten, die entlang eines komplexen Musters von BrĂŒchen an der OberflĂ€che und aktiven Störungen ausgebildet sind. Um diese Beobachtungen interpretieren und in den regionalen tektonischen Zusammenhang stellen zu können, wurde die SAR-Analyse durch seismologische und geologische Felduntersuchungen ergĂ€nzt. Die hauptsĂ€chliche Freisetzung der seismischen Energie des Nura-Erdbebens scheint an der frontalen Pamir-Ăberschiebung erfolgt zu sein, wĂ€hrend die Hauptverformung und OberflĂ€chenrupturen im Liegenden und entlang der NE-SW streichenden Irkeshtam-Störung auftraten. Unter Nutzung von InSAR-Daten von den aufsteigenden und absteigenden Satelliten-Bahnen sowie von Pixel-Versatz-Messungen wurde das Nura-Erdbeben als ein segmentierter Bruch modelliert. Dabei entspricht ein Segment einer steilen spröden Verwerfung an der frontalen Pamir-Ăberschiebung, wĂ€hrend zwei andere Segmente mittel-steile und reibungsarme Verwerfungen an der Irkeshtam-Störung zeigen. Die integrierte Analyse der koseismischen Deformation spricht fĂŒr eine Segmentierung des Bruches und eine Verteilung der Verformung in Folge des Erdbebens. Dies hat möglicherweise einen Gebirgskeil im Ă€uĂersten östlichen Teil der Pamir-Alai-Kollisionszone aktiviert. Zudem könnte die Art der Segmentierung mit der Ablagerung von PalĂ€ogenen Evaporiten assoziiert sein.
(2) Der zweite Schwerpunkt wurde auf tief-liegende langsame Böschungsverformungen gelegt, die insbesondere im Gebiet des markanten Ăbergangs zwischen dem Fergana-Tal und dem Hochrelief der Alai-Gebirgskette ausgeprĂ€gt sind. Die Alai-Kette stellt einen aktiven Gebirgskeil der Pamir-Tien-Shan-Kollisionszone dar, welche als ein sich stufenweise nach Norden fortsetzender Falten- und ĂberschiebungsgĂŒrtel beschrieben wird. Die interferometrische Analyse von ALOS/PALSAR-Radardaten deckt einen Zeitraum von vier Jahren ab (2007-2010) und nutzt den âSmall-Basline-Subsetâ (SBAS) Zeitreihenansatz um OberflĂ€chendeformationen mit Millimeter-Genauigkeit zu bestimmen. 118 Interferogramme wurden analysiert, um die rĂ€umlich-kontinuierlichen Bewegungen mit HangabwĂ€rts-Geschwindigkeiten von bis zu 71 mm/Jahr zu beobachten. Die erhaltenen Raten weisen auf eine langsame Bewegung von tief-verwurzelten Hangrutschungen wĂ€hrend der Beobachtungszeit hin. Wir korrelierten diese Bewegungen mit Niederschlags- und seismischen Beobachtungen. Die Ergebnisse deuten darauf hin, dass die gröĂten Deformationen mit den Regenmengen der drei vorhergehenden Monate und mit einem Erdbebenereignis korrelieren. Im nĂ€chsten Schritt wurden die tektonischen und lithologischen VerhĂ€ltnisse mit den Mustern der OberflĂ€chendeformation kombiniert, um das rĂ€umliche Muster der Hangrutschungsprozesse zu verstehen. Wir zeigen, dass die lithologischen und tektonischen Strukturen die Hauptkontrollmechanismen fĂŒr das Auftreten von Hangrutschungen und fĂŒr den Grad der OberflĂ€chendeformation sind. DarĂŒber hinaus ist die aktive Kontraktion und Einengungstektonik an der Vorderseite und Front des kontinentalen Akkretionskeils der hauptsĂ€chliche Mechanismus der Relieferhaltung. Einige der langsameren aber kontinuierlich in Bewegung befindlichen InstabilitĂ€ten stehen in direktem Zusammenhang mit der tektonisch aktiven Störungen und Hebung sowie mit unkonsolidierten, jung-quartĂ€ren synorogenen Molassesedimenten. Unser Ansatz bietet eine neue Kombination von InSAR-Techniken und tektonischen Aspekten um HanginstabilitĂ€ten in tektonisch aktiven Gebirgsfronten im Kirgisischen Tien Shan zu lokalisieren und zu verstehen
ALOS/PALSAR InSAR Time-Series Analysis for Detecting Very Slow-Moving Landslides in Southern Kyrgyzstan
This study focuses on evaluating the potential of ALOS/PALSAR time-series data to analyze the activation of deep-seated landslides in the foothill zone of the high mountain Alai range in the southern Tien Shan (Kyrgyzstan). Most previous field-based landslide investigations have revealed that many landslides have indicators for ongoing slow movements in the form of migrating and newly developing cracks. L-band ALOS/PALSAR data for the period between 2007 and 2010 are available for the 484 km2 area in this study. We analyzed these data using the Small Baseline Subset (SBAS) time-series technique to assess the surface deformation related to the activation of landslides. We observed up to ±17 mm/year of LOS velocity deformation rates, which were projected along the local steepest slope and resulted in velocity rates of up to â63 mm/year. The obtained rates indicate very slow movement of the deep-seated landslides during the observation time. We also compared these movements with precipitation and earthquake records. The results suggest that the deformation peaks correlate with rainfall in the 3 preceding months and with an earthquake event. Overall, the results of this study indicated the great potential of L-band InSAR time series analysis for efficient spatiotemporal identification and monitoring of slope activations in this region of high landslide activity in Southern Kyrgyzstan
Optimization of health facility locations in Osh City, Kyrgyzstan
Basic information regarding location of existing facilities, their accessibility and development trends, in relation to socio-economic structure of a city is needed in order to prepare its developmental plan. Re-location of any service may not be feasible economically, but location-allocation models can be used to identify new potential locations. This study is an attempt to simulate new potential locations and evaluate the feasibility of optimization models for planning additional health facility in the Osh city. The result of the study shows the potential of the p-median approach for optimization of the location of various public services. The contribution of GIS to optimization techniques is mainly its use as a method for data gathering and visualization of the result. These two technologies can be fully integrated to provide a powerful tool for spatial decision support
Deep-seated gravitational slope deformation (DSGSD) and slow-moving landslides in the southern Tien Shan Mountains:new insights from InSAR, tectonic and geomorphic analysis
We investigated deep-seated gravitational slope deformation (DSGSD) and slow mass movements in the southern Tien Shan Mountains front using synthetic aperture radar (SAR) time-series data obtained by the ALOS/PALSAR satellite. DSGSD evolves with a variety of geomorphological changes (e.g. valley erosion, incision of slope drainage networks) over time that affect earth surfaces and, therefore, often remain unexplored. We analysed 118 interferograms generated from 20 SAR images that covered about 900 km2. To understand the spatial pattern of the slope movements and to identify triggering parameters, we correlated surface dynamics with the tectono-geomorphic processes and lithologic conditions of the active front of the Alai Range. We observed spatially continuous, constant hillslope movements with a downslope speed of approximately 71 mm yearâ1 velocity. Our findings suggest that the lithological and structural framework defined by protracted deformation was the main controlling factor for sustained relief and, consequently, downslope mass movements. The analysed structures revealed integration of a geological/structural setting with the superposition of CretaceousâPaleogene alternating carbonatic and clastic sedimentary structures as the substratum for younger, less consolidated sediments. This type of structural setting causes the development of large-scale, gravity-driven DSGSD and slow mass movement. Surface deformations with clear scarps and multiple crest lines triggered planes for large-scale deep mass creeps, and these were related directly to active faults and folds in the geologic structures. Our study offers a new combination of InSAR techniques and structural field observations, along with morphometric and seismologic correlations, to identify and quantify slope instability phenomena along a tectonically active mountain front. These results contribute to an improved natural risk assessment in these structures
Radar remote sensing for surveying and monitoring of earthquakes and mass movements in Southern Kyrgyzstan
Kyrgyzstan is landlocked mountainous nation of around five million people, which borders China, Kazakhstan, Tajikistan and Uzbekistan. The total area of high mountainous terrain, alpine meadows and pastures exceeds 70% of the Republicâs territory, whereas the greater part of the Kyrgyz Republic is occupied by the Tien-Shan mountains. Kyrgyzstan is a highly active seismic region and has been shaken by numerous significant earthquakes as a consequence of the ongoing collision between the Indian and Eurasian tectonic plates. In the result, the mountainous country is faced with a large variety of natural hazards (mainly earthquakes, large landslides and floods) which frequently lead to the occurrence of natural disaster (e.g., 1994: about 1,000 landslides failed and 115 human fatalities; 2008: Nura earthquake M=6.6, 74 human fatalities and 150 injured, 90 glacial lakes endangered for regularly occurring outburst floods). Under these conditions, there is high demand for efficient and spatially differentiated hazard assessment requiring an improved understanding of natural processes with high hazardous potential. Since large areas with often limited accessibility are affected, satellite remote sensing plays an important role in contributing to improved process knowledge in this region (Roessner et al., 2005). In the presented work the potential of advanced remote sensing techniques based on Synthetic Aperture Radar (SAR) satellite data is investigated for characterizing spatio-temporal surface changes related to mass movement and earthquakes. Methodological focus has been put on using Differential SAR Interferometry (InSAR) based on data from different satellites for detecting surface displacements as a consequence of slope instabilities and earthquakes in Southern Kyrgyzstan. In the presented work we focus on one study site of high landslide activity in the Osh province and on another study site which has been affected by the recent destructive Nura earthquake in 2008
ALOS/PALSAR InSAR Time-Series Analysis for Detecting Very Slow-Moving Landslides in Southern Kyrgyzstan
This study focuses on evaluating the potential of ALOS/PALSAR time-series data to analyze the activation of deep-seated landslides in the foothill zone of the high mountain Alai range in the southern Tien Shan (Kyrgyzstan). Most previous field-based landslide investigations have revealed that many landslides have indicators for ongoing slow movements in the form of migrating and newly developing cracks. L-band ALOS/PALSAR data for the period between 2007 and 2010 are available for the 484 km2 area in this study. We analyzed these data using the Small Baseline Subset (SBAS) time-series technique to assess the surface deformation related to the activation of landslides. We observed up to ±17 mm/year of LOS velocity deformation rates, which were projected along the local steepest slope and resulted in velocity rates of up to â63 mm/year. The obtained rates indicate very slow movement of the deep-seated landslides during the observation time. We also compared these movements with precipitation and earthquake records. The results suggest that the deformation peaks correlate with rainfall in the 3 preceding months and with an earthquake event. Overall, the results of this study indicated the great potential of L-band InSAR time series analysis for efficient spatiotemporal identification and monitoring of slope activations in this region of high landslide activity in Southern Kyrgyzstan
Permafrost seasonal surface changes revealed from Sentinel-1 InSAR time-series, Yamal peninsula
Widespread thawing of permafrost in the northern Eurasian continent causes severe problems for infrastructure and global climate. We test the potential of Sentinel-1 SAR imagery to enhance detection of permafrost surface changes in the Siberian lowlands of the northern Eurasian continent at the Yamal peninsula site. We used InSAR time-series technique to detect seasonal surface movements related to permafrost active layer changes. The satellite InSAR time-series analysis has detected continuous movements, subsidence in three zones, which have occurred during the time period from 2017 to 2018. Observed subsidence zones show up to 180mmyr1 rates of seasonal active layers changes. These seasonal ground displacement patterns align well with lithology and linked to anthropogenic impact on the permafrost surface changes in the area. The results show that Sentinel-1 mission is of great importance for the longer-term monitoring of active layer thickening in permafrost regions. The combined analyses of the obtained InSAR time series with additional field observations may support regular process monitoring as part of a global warming risk assessment
Methane in Gas Shows from Boreholes in Epigenetic Permafrost of Siberian Arctic
The gas shows in the permafrost zone represent a hazard for exploration, form the surface features, and are improperly estimated in the global methane budget. They contain methane of either surficial or deep-Earth origin accumulated earlier in the form of gas or gas hydrates in lithological traps in permafrost. From these traps, it rises through conduits, which have tectonic origin or are associated with permafrost degradation. We report methane fluxes from 20-m to 30-m deep boreholes, which are the artificial conduits for gas from permafrost in Siberia. The dynamics of degassing the traps was studied using static chambers, and compared to the concentration of methane in permafrost as analyzed by the headspace method and gas chromatography. More than 53 g of CH4 could be released to the atmosphere at rates exceeding 9 g of CH4 m−2 s−1 from a trap in epigenetic permafrost disconnected from traditional geological sources over a period from a few hours to several days. The amount of methane released from a borehole exceeded the amount of the gas that was enclosed in large volumes of permafrost within a diameter up to 5 meters around the borehole. Such gas shows could be by mistake assumed as permanent gas seeps, which leads to the overestimation of the role of permafrost in global warming