Detection of geological faults using a nuclear method

1992 ◽  
Vol 161 (2) ◽  
pp. 339-350
Author(s):  
N. E. Whitehead
Keyword(s):  
Geological Faults ◽  
Nuclear Method

IDENTIFICAÇÃO DAS FEIÇÔES GRANÍTICAS DO MUNICÍPO DE IRAUÇUBA-CEARÁ

2019 ◽  
Vol 21 (2) ◽  
pp. 51-61
Author(s):  
Abner Monteiro Nunes Cordeiro ◽  
Rayane Barroso Araújo ◽  
Frederico De Holanda Bastos ◽  
Augusto César Praciano Sampaio
Keyword(s):  
Field Work ◽  
Granitic Rocks ◽  
Surface Erosion ◽  
Climatic Fluctuations ◽  
Geological Faults ◽  
Dry Climates ◽  
Evolution Understanding ◽  
Geomorphological Features

A exumação de rochas graníticas do Complexo Tamboril-Santa Quitéria, especificamente, na superfície de aplainamento do município de Irauçuba, Ceará, tem revelado uma grande variedade de feições geomorfológicas que se justificam por fatores litológicos e evidentes flutuações climáticas cenozoicas, comandadas, sobretudo, por morfogênese mecânica, associada a climas secos. São relevos residuais como, maciços, cristas, inselbergs, inselguebergs, lajedos e blocos saprolitizados (boulders) em diferentes graus de desenvolvimento que se sobressaem em meio à superfície erosiva rebaixada, regionalmente conhecida como depressão sertaneja. Nesse trabalho, foram identificadas diferentes formas de relevo granítico condicionadas, sobretudo por intempéries de subsuperfície, controladas por falhas e fraturas, e por remoção do regolito através da erosão superficial, além de eventos de esfoliação. Essas formas graníticas constituem peças fundamentais na compreensão da evolução paleoclimática do município de Irauçuba. Para a realização do presente trabalho foram usadas as seguintes metodologias: revisão bibliográfica, levantamento cartográfico e trabalho de campo.Palavras-chave: Feições graníticas; Superfícies de aplainamento; Erosão diferencial. ABSTRACTThe granitic rocks exhumation of Complexo Tamboril-Santa Quitéria, specifically, on the planing surface of Irauçuba county, Ceará, has revealed a great variety of geomorphological features that are justified by lithologic factors and evident Cenozoic climatic fluctuations, mainly, headed by mechanical morphogenesis, associated with dry climates. Residual reliefs like rocky massives, residual ridges, inselbergs and inselguebergs, slab stones and boulders in different degrees of development stand out in the middle of the lowered erosive surface, regionally known by “depressão sertaneja”. In this study, different forms of granite relief were identified, specially conditioned by subsurface erosion, controlled by geological faults and fractures, but also by regolith removal through surface erosion, plus exfoliation spheroidal events. These granitic features are fundamental in paleoclimatic evolution understanding of Irauçuba municipality. For the accomplishment of the present work the following methodology was used: bibliographical revision, cartographic survey and field work. For the accomplishment of the present work the following methodology was used: bibliographical revision, cartographic survey and field work.Keywords: Granitic features; Planing surface; Differential erosion.RESUMENLa exhumación de rocas graníticas del Complejo tamboril-Santa Quitéria, específicamente en la superficie de aplanado del municipio de Irauçuba, Ceará, ha revelado una gran variedad de rasgos geomorfológicos que se justifican por factores litológicos y evidentes fluctuaciones climáticas cenozoicas, comandadas principalmente por morfogénesis mecánica, asociada a climas secos. Son relieves residuales como, macizos, crestas, Inselbergs, inselguebergs, losas y bloques saprolitizados (Boulders) en diferentes grados de desarrollo que sobresalen en medio de la superficie erosiva rebajada, regionalmente conocida como depresión sertaneja. En este trabajo, se identificaron diferentes formas de relieve granítico condicionadas, principalmente por intemperies de subsuperficie, controladas por fallas y fracturas, y por eliminación del regolito a través de la erosión superficial, además de eventos de exfoliación. Estas formas graníticas constituyen piezas fundamentales en la comprensión de la evolución paleoclimática del municipio de Irauçuba. Para la realización del presente trabajo se utilizaron las siguientes metodologías: revisión bibliográfica, levantamiento cartográfico y trabajo de campo.Palabras clave: Facciones graníticas; Superficies de aplanado; Erosión diferencial.

scholarly journals Improving the criteria for choosing the strategies in management by geotechnical systems

2019 ◽  
Vol 109 ◽  
pp. 00048
Author(s):  
Yevhen Lapshyn ◽  
Robert Molchanov ◽  
Borys Blyuss ◽  
Nataliia Osadcha
Keyword(s):  
Game Theory ◽  
Optimal Strategy ◽  
Optimal Strategies ◽  
Mineral Deposits ◽  
Underground Space ◽  
Infrastructure Development ◽  
Main Indicator ◽  
Geological Conditions ◽  
Geological Faults

The conclusion has been made about the necessity to choose the optimal strategies for management by geotechnical systems, based on the analysis of geological faults, which are the main indicator of the mining and geological conditions that characterize the mineral deposits, as well as on the parameters for the infrastructure development of the underground space. The methodological peculiarity of solving the problems set is the use of game theory with modified criteria of Wald, maximax and Savage, since the manifestation of specific geological faults is probabilistic in nature. When choosing the optimal strategy, the average linear deviations of gains or risks are taken into account.

scholarly journals Instruments and Methods Snow Density Profiling by Nuclear Means

1966 ◽  
Vol 6 (43) ◽  
pp. 171-176
Author(s):  
Robert D. Leighty
Keyword(s):  
Soil Moisture ◽  
Field Investigation ◽  
Present Form ◽  
Snow Density ◽  
Nuclear Technique ◽  
Density Profiles ◽  
Snow Stratigraphy ◽  
Modes Of Processing ◽  
Nuclear Detectors ◽  
Nuclear Method

Abstract During the period 8–19 May 1963 a preliminary field investigation was conducted in Greenland to determine the feasibility of using a nuclear technique to determine snow and ice density profiles. A standard nuclear soil-moisture depth probe was used with two modes of processing and recording the nuclear pulses. Example data are compared with snow densities obtained by the standard weighing technique. The nuclear method was found to be feasible; however, deficiencies related to poor resolution render the probe unusable for detailed profiling of snow stratigraphy in its present form, but expected progress in nucleonics should enable improved resolution and accuracy to be achieved by improvement of nuclear detectors.

scholarly journals Characterization of seismogenic crustal faults in the Gulf of Guayaquil, Ecuador

2018 ◽  
Vol 46 (1) ◽  
pp. 66 ◽  
Author(s):  
Kervin Chunga ◽  
Felipe Ochoa-Cornejo ◽  
Maurizio Mulas ◽  
Theofilos Toulkeridis ◽  
Edgar Menéndez
Keyword(s):  
Methodological Approach ◽  
Active Faults ◽  
Coastal Region ◽  
Seismic Hazard Assessment ◽  
Accretionary Prism ◽  
Regression Equations ◽  
Geological Faults ◽  
Gulf Of Guayaquil ◽  
Ground Damage ◽  
Santa Elena

Few moderate-to-strong earthquakes associated with active and capable geological faults have been documented for the southern coastal region of Ecuador. The seismic record of Ecuador initiates with the Guayaquil earthquake in 1787 (Mw 6.5), followed by the 1943 (Mw 6.2), and the most recent one in 1980 (Mw 6.1). The available data is insufficient to evaluate the seismic hazards associated with faults capable of generating seismic events of magnitude Mw≥6.0 in the region. Also, earthquakes of minor magnitudes can be disregarded as they do not induce significant ground coseismic effects. In this context, this study presents a catalog of geological faults, delineating 40 segments of capable and active faults on the sea floor of the Gulf of Guayaquil and inland segments of Guayas, Santa Elena, and El Oro provinces. This methodological approach estimates a variety of seismicity levels ranging between Mw 6.2 and Mw 7.2, with rock peak ground accelerations between 0.24 g and 0.41 g. These values have been obtained from empirical regression equations applied to the length of capable geological faults. The F-40 seismogenic structure located in the accretionary prism, close to the subduction zone, is capable of generating Mw 8.2 earthquakes and potentially causing coseismic ground damage to the city of Guayaquil located ca. 177 km to the NE. Furthermore, local tsunami hazards may affect severely areas that are densely populated, with developing industrial areas, on the coast of the Gulf of Guayaquil. This structural geological analysis provides useful new data for seismic hazard assessment.

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