The Alid Volcanic District (Eritrea): Remote sensing analysis and preliminary conceptual model of the geothermal reservoir.

The principal aim of this work was to improve the characterization of Mt. Alid geothermal system (eastern Eritrea), considered the most favourable geothermal resource of the country. To conduct a detailed remote sensing analysis, a high resolution digital elevation model has been provided, the new ALOS DEM (courtesy of JAXA). Before its use, it required a validation process, using GCPs and other already validated data, such as SRTM. With the aid of different DEMs, Bing and Google high resolution images and processed Landsat 8 acquisitions, a remote sensing analysis has been conducted, in order to characterise geological, geomorphological and geostructural features of the Alid area and surrounding. Two main structural lineaments have been found: a NNW-SSE normal fault system, strictly related to the regional rift tectonic context, and a NE-SW trend with a dextral strike-slip component, related to the presence of the underlying shallow magma intrusion. The results obtained from the remote sensing approach have revealed that the crossing of the two fault systems caused the ascent of geothermal steam to the surface, since the position of fumarolic vents seems to be closely related. The mapping of geological units has brought the realization of and an updated and more accurate geological map of the Alid geothermal district. A preliminary fieldwork, aimed at validating the remote sensing analysis, was carried out in February 2015 and confirmed, to a first approximation, the validity of the mapping. An analysis on ASTER TIR images has also been conducted, to extract heat anomalies from processed thermal bands and measure the heat contribution due to the presence of surface geothermal manifestations. Normalized temperature has confirmed that thermal anomalies are related with fumaroles and has given us promising results for further detailed studies. An attempt to quantify the potential of the geothermal resource has been made. In cooperation with the IGG-CNR research institute of Florence, a first numerical model of the geothermal reservoir has been realized. Simulation results indicate a possible reservoir temperature of 260-270 °C, a pressure of about 50 bar and a vapour fraction of 0.7. These values are coherent with a dominant steam geothermal reservoir

Geothermal Distribution Analysis of Geureudong Volcano Based On Satellite Data and Fault Fracture Density (FFD)

Abstract: Geureudong Volcano area, Bener Meriah, has the potential to be developed as a renewable energy source. Analysis of the distribution of geothermal manifestations can be done with remote sensing techniques and direct measurement. Furthermore, information on geomorphological conditions, surface temperature, and geothermal potential distribution can be known based on the density value on the FFD (Fault Fracture Density) map and satellite image processing results. Data processing uses ArcGIS and ENVI software concerning geothermal manifestations. The analysis was performed by converting DEMNAS data to a hillshade for drawing straightness structures related to the fault. Image data processing to obtain vegetation density (NDVI), hydrological state (NDWI), and surface temperature distribution (LST). NDWI values are inversely proportional to NDVI. The LST value depends on the density of the vegetation; the higher the vegetation density, the lower the surface temperature. The FFD map is divided into three levels i.e. low (0-0.17 km/km2), moderate (0.17-0.47 km/km2) and high (0.47-1.2 km/km2). The distribution of geothermal potential is at medium and high-density levels, including the Silih Nara, Wih Pesam, and Pintu Rime Gayo areas. The straightness direction is in the north-south and southeast-northwest positions. Based on the NDVI, NDWI, and LST map analysis results, geothermal energy distribution has a rare to moderate vegetation density with surface temperatures ranging from 25.8oC-39.6oC. The result clearly shows that the Geureudong geothermal distribution is initial information before in situ exploration is carried out.Abstrak: Gunung berapi Geureudong, Bener Meriah, sangat prospektif untuk dikembangkan terutama sebagai sumber energi terbarukan. Analisis sebaran manifestasi panas bumi dapat dilakukan dengan teknik penginderaan jauh dan pengukuran langsung. Informasi geomorfologi, temperatur permukaan dan sebaran potensi panas bumi dapat diketahui berdasarkan nilai densitas pada peta FFD (Fault and Fracture Density) dan hasil pengolahan citra satelit Landsat 8. Pemrosesan data menggunakan perangkat lunak ArcGIS dan ENVI yang terkait dengan manifestasi panas bumi. Analisis dilakukan dengan mengubah data DEMNAS menjadi hillshade untuk menggambar struktur kelurusan yang berhubungan dengan sesar. Pengolahan data citra untuk mendapatkan kerapatan vegetasi (NDVI), keadaan hidrologi (NDWI) dan distribusi suhu permukaan (LST). Nilai NDWI berbanding terbalik dengan NDVI. Nilai LST tergantung pada kerapatan vegetasi, semakin tinggi kerapatan vegetasi maka semakin rendah suhu permukaan. Peta FFD dibagi menjadi tiga tingkatan; rendah (0-0,17 km/km2), sedang (0,17-0,47 km/km2) dan tinggi (0,47-1,2 km/km2). Sebaran potensi panas bumi berada pada tingkat kepadatan sedang dan tinggi, meliputi kawasan Silih Nara, Wih Pesam dan Pintu Rime Gayo. Arah kelurusan berada pada posisi utara-selatan dan tenggara-barat laut. Berdasarkan hasil analisis peta NDVI, NDWI dan LST didapatkan bahwa sebaran energi panas bumi memiliki kerapatan vegetasi jarang hingga sedang dengan temperatur permukaan berkisar antara 25.8oC-39.6oC.Hasil yang diperolehkan menunjukkan bahwa sebaran panas bumi Geureudong dengan sangat jelas tergambar sebagai informasi awal sebelum dilakukan eksplorasi lapangan (in situ)

Investigations into the degassing and eruption mechanisms of Nyamuragira volcano, Democratic Republic of the Congo (Africa)

One of two active volcanoes in the western branch of the East African Rift, Nyamuragira (1.408ºS, 29.20ºE; 3058 m) is located in the D.R. Congo. Nyamuragira emits large amounts of SO2 (up to ~1 Mt/day) and erupts low-silica, alkalic lavas, which achieve flow rates of up to ~20 km/hr. The source of the large SO2 emissions and pre-eruptive magma conditions were unknown prior to this study, and 1994-2010 lava volumes were only recently mapped via satellite imagery, mainly due to the region’s political instability. In this study, new olivine-hosted melt inclusion volatile (H2O, CO2, S, Cl, F) and major element data from five historic Nyamuragira eruptions (1912, 1938, 1948, 1986, 2006) are presented. Melt compositions derived from the 1986 and 2006 tephra samples best represent pre-eruptive volatile compositions because these samples contain naturally glassy inclusions that underwent less post-entrapment modification than crystallized inclusions. The total amount of SO2 released from the 1986 (0.04 Mt) and 2006 (0.06 Mt) eruptions are derived using the petrologic method, whereby S contents in melt inclusions are scaled to erupted lava volumes. These amounts are significantly less than satellite-based SO2 emissions for the same eruptions (1986 = ~1 Mt; 2006 = ~2 Mt). Potential explanations for this observation are: 1) accumulation of a vapor phase within the magmatic system that is only released during eruptions, and/or 2) syn-eruptive gas release from unerupted magma. Post-1994 Nyamuragira lava volumes were not available at the beginning of this study. These flows (along with others since 1967) are mapped with Landsat MSS, TM, and ETM+, Hyperion, and ALI satellite data and combined with published flow thicknesses to derive volumes. Satellite remote sensing data was also used to evaluate Nyamuragira SO2 emissions. These results show that the most recent Nyamuragira eruptions injected SO2 into the atmosphere between 15 km (2006 eruption) and 5 km (2010 eruption). This suggests that past effusive basaltic eruptions (e.g., Laki 1783) are capable of similar plume heights that reached the upper troposphere or tropopause, allowing SO2 and resultant aerosols to remain longer in the atmosphere, travel farther around the globe, and affect global climates

Spatial and Temporal Study of Heat Transport of Hydrothermal Features in Norris Geyser Basin, Yellowstone National Park

Monitoring the dynamic thermal activity in Yellowstone National Park is required by the United States Congress. The continuous monitoring is important to maintain the safety of the visitors and park service personnel, plan and relocate infrastructure, and study potential impact from nearby geothermal development including oil and gas industry. This dissertation is part of a study initiated in the early 2000s to monitor the thermal activity of dynamic areas within the Park, using airborne remote sensing imagery. This study was focused in Norris Geyser Basin, the hottest geyser basin in the park, located near the northwestern rim of the Yellowstone’s caldera. The study is considered the first long-term comprehensive airborne remote sensing study in the basin which took place between August 2008 and October 2013. In this study, at least one 1-meter resolution thermal infrared image and three-band images (multispectral) were acquired and used to estimate year-to-year changes in radiant temperature, radiant flux, and radiant power from the thermal source in Norris. Presence of residual radiant flux in the ground from absorbed solar radiation and atmospheric longwave radiation was the main challenge to compere year-to-year changes in the thermal activity. This residual flux is included in the total radiant flux calculated through the remote sensing images which gives false estimates of the flux generated from the underling thermal source. Two methods were suggested in Chapters 2 and 4 of this dissertation to estimate the residual radiant flux. A method was developed in Chapter 2 to estimate the residual radiant flux in a bare ground area covered with hydrothermal siliceous sinter deposit. The method compared ground-based measurements with high spatial resolution airborne remote sensing measurements to estimate the residual radiant flux. In Chapter 4, a method was developed to estimate the residual radiant flux in the six surface classes in Norris, including bare ground, bare ground with siliceous sinter deposit, lakes and pools, river, forest, and grass. The assumptions and implications of each method were discussed to suggest a reliable method to estimate the geothermal radiant flux after subtracting the absorbed residual radiant flux. Chapter 3 provides an analysis of the four components of heat flux in the ground surface, including conduction of sensible heat, convection of sensible heat by liquid water and water vapor, and convection of latent heat by water vapor. The main purpose from the analysis was to assess the hypothesis that the convection and latent heat flux are negligible which therefore supported the results obtained from the analysis in Chapters 2 and 4

Lateritic palaeosols of N.E. Africa: a remote sensing study

Remote sensing data and image processing techniques are used increasingly to aid scientific investigation and address geological problems in areas that are difficult to map by conventional methods. This thesis explores how multi spectral satellite data, supported by traditional geological techniques, facilitate a study of lateritic palaeosols. The work centres on laterites, which are thin but important elements of the Phanerozoic stratigraphy of NE Africa. They immediately pre-date midOligocene flood basalts and, if mapped, can be used to delineate a flood basalt-Iaterite contact and define the pre-30 Ma African Surface and uplift patterns. They have important engineering properties and are key to understanding basement alteration and its associated mineralization. They affect agriculture and groundwater quality and retention - essential in Sub-Saharan Aflica where access to safe water is limited. They dominate the landscape, yet are unmapped and marginalised in the literature. Their geological context supports a laterite-focused remote sensing mapping strategy. A strategy for geologic mapping of laterites based on their simple mineralogy and spectral characteristics that distinguish them from other rocks is developed. Methods for mapping are presented using Earth Observation data. The outcome is a series of regional geological maps of Eritrea and Ethiopia. These reveal that laterite cover is more extensive than previously thought and enable further lines of research. The maps provide a means of regional dating of laterites, which, together with ages obtained for overlying flood basalts and new basement cooling ages, indicate a major planation during the Palaeozoic and constrain the timing of associated uplift and erosion. A regional review of Mesozoic-Cenozoic climatic, strati graphic and structural evolution is presented and a model of Neogene deformation of the lateriteflood basalt datum is produced. Finally, laterite maps, petrographic and geochemical evidence are used to access basic essentials of life: clean water, a safe environment and a sustainable economy

Urban morphology analysis by remote sensing and gis technique, case study: Georgetown, Penang

This paper was analysed the potential of applications of satellite remote sensing to urban planning research in urban morphology. Urban morphology is the study of the form of human settlements and the process of their formation and transformation. It is an approach in designing urban form that considers both physical and spatial components of the urban structure. The study conducted in Georgetown, Penang purposely main to identify the evolution of urban morphology and the land use expansion. In addition, Penang is well known for its heritage character, especially in the city of Georgetown with more than 200 years of urban history. Four series of temporal satellite SPOT 5 J on year 2004, 2007, 2009 and 2014 have been used in detecting an expansion of land use development aided by ERDAS IMAGINE 2014. Three types of land uses have been classified namely build-up areas, un-built and water bodies show a good accuracy with achieved above 85%. The result shows the built-up area significantly increased due to the rapid development in urban areas. Simultaneously, this study provides an understanding and strengthening a relation between urban planning and remote sensing applications in creating sustainable and resilience of the city and future societies as well

Classification of fires in coal waste dumps based on Landsat, Aster thermal bands and thermal camera in Polish and Ukrainian mining regions

A self-heating intensity index (SHII) based on the highest (pixel max.) and lowest (pixel min.) values taken from satellite thermal maps of burning coal waste dumps are proposed. The index enables the classification of such fires in Ukrainian- and Polish coal waste dumps. Both in Ukraine and in Poland, varying thermal intensities during 1985–2019 are revealed, using the SHII and following thermal intensity threshold values, namely, extreme thermal activity ([7), advanced (3–7), moderate (3–1.5), initial (1.5–1), no activity (\1). The SHII shows decreasing thermal activity in the selected Ukrainian coal waste dumps during 2017–2019. It aids in reconstructing the thermal history of the dumps. Analysis of satellite images revealed a large number of burning coal waste dumps in the Donetsk Coal Basin (Ukraine) with high thermal activity. Such burning likely reflects large amounts of organic matter and sulphides in the dumped material subjected to self-heating and self-burning processes, lack of compaction of the coal waste and/or high methane contents. Comparison of SHII values calculated from satellite- and drone thermal-camera images were compared to show that SHII from drone thermal images have much higher values than those from satellite images; the former have better resolution. Thus, SHII from Landsat- and drone images should be used separately in dump heating studies

Data Processing and Modeling on Volcanic and Seismic Areas

This special volume aims to collecg new ideas and contributions at the frontier between the fields of data handling, processing and modeling for volcanic and seismic systems. Technological evolution, as well as the increasing availability of new sensors and platforms, and freely available data, pose a new challenge to the scientific community in the development new tools and methods that can integrate and process different information. The recent growth in multi-sensor monitoring networks and satellites, along with the exponential increase in the spatiotemporal data, has revealed an increasingly compelling need to develop data processing, analysis and modeling tools. Data processing, analysis and modeling techniques may allow significant information to be identified and integrated into volcanic/seismological monitoring systems. The newly developed technology is expected to improve operational hazard detection, alerting, and management abilities