KARAKTERISTIK STRUKTUR GEOLOGI DAN PERANANNYA TERHADAP SISTEM PANAS BUMI NAGE, KABUPATEN NGADA, PROVINSI NUSA TENGGARA TIMUR

Daerah Nage merupakan bagian dari jalur vulkanisme Busur Sunda-Banda yang membentuk rangkaian en-echelon di Pulau Flores. Tatanan tektonik regional di Pulau Flores yang cukup kompleks menyebabkan adanya struktur geologi yang intensif di daerah penelitian. Metode penelitian yang digunakan meliputi pengamatan struktur geologi melalui analisis kelurusan topografi, kelurusan sungai, fitur melingkar dan densitas kelurusan (fracture fault density) dengan menggunakan citra DEMNAS serta pengukuran secara langsung di lapangan terhadap unsur-unsur struktur geologi primer dan sekunder pada 87 stasiun pengamatan. Pengukuran terhadap 441 kedudukan struktur geologi di daerah penelitian, menunjukkan bahwa struktur geologi sekunder, utamanya berupa kekar gerus, yang berguna untuk membuktikan kehadiran sesar yang memotong batuan berumur Kuarter pada daerah penelitian. Hasil analisis kinematika menyimpulkan bahwa terdapat sesar geser oblik berarah baratlaut-selatan tenggara dan timurlaut-baratdaya serta sesar geser berarah timur laut-baratdaya. Daerah penelitian terdapat fitur melingkar yang berasosiasi dengan peruntuhan kaldera dan pembentukan kawah. Analisis dinamik sesar untuk menentukan arah tegasan kompresif menunjukkan bahwa daerah penelitian mengalami deformasi kompresional berarah utara timurlaut-selatan baratdaya dengan arah tegasan maksimum (σ1) 16°, N 203°E dan arah tegasan minimum (σ3) 17,5°, N 297,1°E. Keberadaan struktur sesar diinterpretasikan memiliki peran sebagai jalur fluida terhadap sistem panas bumi Nage yang tampak dari kehadiran manifestasi panas bumi dan alterasi hidrotermal. Berdasarkan konfigurasi sesar, manifestasi, dan alterasi hidrotermal disimpulkan bahwa setidaknya terdapat tiga aliran fluida, yakni aliran fluida hidrotermal yang naik melalui sesar F1 dan dibatasi sesar F3, aliran fluida yang naik melalui sesar F2, dan aliran fluida hasil pendidihan yang naik melalui F10.

GIS-Based Weights-of-Evidence Model for Landslide Susceptibility Mapping and Assessment in the Hillslopes of Bujumbura, Burundi

The aim of this research is the modelling of landslide susceptibility in the hillslopes of Bujumbura using the Weights-of-Evidence model, a probabilistic data modelling approach relevant for predicting future landslides at a regional scale. Initially, characteristics and spatial mapping of different landslides type were identified (fall, flow, slide, complex) by thorough interpretation of high-resolution remote sensing data (mountainous areas with difficult access) and intensive fieldwork. Subsequently, the main landslides controlling factors were selected (lithology, fault density, land use, drainage density, slope aspect, curvature, slope angle, and elevation) using in-depth field knowledge and relevant literature. A landslide inventory map with a total of 569 landslide sites was constructed using the data from various sources. Out of those 569 landslide sites, 285 (50.1%) of the data taken before the 2000s was used for training and the remaining 284 (49.9%) sites (post-2000 events) were used for the accuracy assessment purpose. Thereafter, a prediction map of future landslides was generated with an accuracy of 73.7%. The main geo-environmental landslides factors retained are the high density of drainage networks, the lithology often made with weathered gneiss, the high fault density, the steep topography and the convex slope curvature. The landslide susceptibility map validated was reclassified into very high, high, moderate, low and very low zones. The established susceptibility map will allow with the interaction of the real terrain to locate roads, dwellings, urban extension areas, dams located in high landslides risk zones. These infrastructures will require intervention to address their vulnerability with new facilities, slope stabilization, creation of bypass roads, etc. The susceptibility map produced will be a powerful decision-making tool for drawing up appropriate development plans. Such an approach will make it possible to mitigate the socio-economic impacts due to slope instabilities.

Analysis of Faults in Sewage Systems with Geographical Information Systems

Wastewater systems are one of the most important infrastructure elements in terms of human and environmental health. In such systems, failures are observed depending on various factors. These failures increase operating and maintenance-repair costs and create threats to human and environmental health. For this reason, these systems should be monitored regularly and the factors causing malfunction should be analyzed. In this study, it is aimed to evaluate and analyze failures occurring in sewerage systems with geographical information systems. For this, the failures in the sewage system of Malatya province between year 2015-2019 were taken into account. It has been determined that the most common types of failure are misuse, in-line sag and deformation, and in-line lubrication. In addition, the highest failure rate occurred in pipes with a diameter of 100-200 mm. In the spatial analysis of faults, inline collapse is generally observed in the central regions, while misuse faults are found to be in the system. It has been observed that factors such as pipe diameter and length, season, traffic load, ground feature, and improper use are effective in the increase in fault density.

Variation of the tectono-magmatic activity along the Reykjanes Ridge: Influence of the Iceland hotspot on the accretionary processes

<p>The Reykjanes Ridge is a 900 km long oblique slow-spreading ridge, formed by individual “en echelon” axial volcanic ridges (AVR), directly under the influence of the Iceland hotspot. From the Reykjanes Peninsula to the Bight fracture zone, the Reykjanes Ridge shows variations in lava chemistry, crustal thickness, thermal structure and ridge morphology, which has been attributed to this influence. Our study focuses on four areas of the ridge mapped and sampled during the cruise MSM75 in 2018. The northern area is characterized by the only known hydrothermal field discovered along the Reykjanes Ridge. The two central areas are located in a region of increasing magma supply. Finally, the southernmost area is underlined by the only magma body ever detected seismically below the Reykjanes Ridge. The analysis combines 15 m resolution ship-based bathymetry, ground-truthing from ROV dives and geochemical analysis of glass samples to look at variations of magma composition, fault density, seamount density and morphology along the ridge axis. Two major parameters influence the distribution and geometry of faults and seamounts: the distance from the hotspot and the accretion state of individual AVR (i.e., magmatic extension vs. tectonic extension). Fracture geometry is highly influenced by the depth of the brittle-ductile boundary that deepens with distance from the plume center, while fault density at the axis reflects different development stages of individual AVR. Seamount morphologies may also reflect individual AVR development, but we also show morphological variation with distance from the hotspot, correlated with the average variation in lava composition and mantle temperature.</p>

Software Matrices Selection for a SDLC Based Software Reliability Prediction Model

Software reliability is one of the essential factors of quality in software engineering like other quality attributes as functionality, usability, maintainability, performance, serviceability, documentation etc. From last few years, several software reliability models have been developed. There is lack of relevant literature which focuses on processes related to SDLC. A SDLC based structure for measurement of reliability has been proposed. Identified software reliability measures which are majorly take place in all levels of early software development phase of SDLC. Considering all measures for reliability estimation will be costly and time taking. So measures are identified which are taking place at each development phase and have high synthetic weight according to selecting criteria based on expert judgment and multi criteria decision making technique. Based on the grading, top ranked measures like completeness, error distribution, fault density etc are identified. Use of recommended metrics will make software reliability estimation more effective and reliable

Optimization of 150 mm 4H SiC Substrate Crystal Quality

Continuous optimization of bulk 4H SiC PVT crystal growth processes has yielded an improvement in 150 mm wafer shape, as well as a marked reduction in stacking fault density. Mean wafer bow and warp decreased by 26% and 14%, respectively, while stacking faults were nearly eliminated from wafers produced using the refined process. These quality enhancements corresponded to an adjustment to key thermal parameters predicted to control intrinsic crystal stresses, and a reduction in crystal dome curvature.

Landslide susceptibility mapping using AHP method and GIS in the peninsula of Tangier (Rif-northern morocco)

The peninsula of Tangier (Northern Morocco) is submitted to a significant number of landslides each year due to its lithological, structural and morphological complexity; which cause a lot of damage to the road network and other related infrastructure. The main objective of this study is to create a landslide indexed susceptibility map of Tangier peninsula, by using AHP (Analytical Hierarchical Processes) model to calculate each factor’s weight. The work is made via GIS by using an ArcGIS AHP extension. In the current research, First of all, the four main types of landslides were identified and mapped from existing documents, works and new data which came from either remote sensing or fieldwork. Lithology, land use, slope, hypsometry, exposure, fault density and drainage network density were used as main parameters controlling the occurrence of the selected landslides. Then, afterward, each parameter is classified into a number of significant classes based on their relative influence on gravitational movement genesis. The validity of the susceptibility zoning map which is obtained through linear summation of indexed maps was tested and cross-checked by inventoried and studied landslides. The obtained landslide susceptibility map constitutes a powerful decision-making tool in land-use planning, i.e. New highways, secondary highways, railways, etc. within the national development program in the Northern provinces. It is a necessary step for the landslides hazard assessment in the Tangier peninsula in northern Morocco.